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In past, the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake had caused collapse of many breakwaters due to failure of their foundations. The seismic behaviour of rubble mound (RM) breakwater is not well understood may be due to limited number of research works done in the area. Therefore, in the present study, a series of shaking table tests were conducted for RM breakwater in order to determine the exact reasons and mechanisms of failure of the breakwater during an earthquake. In addition, a novel countermeasure technique was developed to mitigate the earthquake-induced damage of RM breakwater. The countermeasure model dealt with geobags as armour units on the both sides instead of conventional armours to increase the stability. The developed model has geogrid and sheet piles in seabed foundation soils of the breakwater. The effectiveness of countermeasure model was examined by comparing with conventional RM breakwater model considering parameters like settlement, horizontal displacement, acceleration-time histories, excess pore water pressure and deformation patterns. Numerical analyses were done to elucidate the failure mechanisms. Overall, the developed model was found to be resilient breakwater against the earthquakes; and the technique could be adopted in practical use on the real ground. • Seismic responses of RM breakwater and foundation soils is studied. • A new countermeasure technique has developed to mitigate earthquake induced damage of RM breakwater. • The geobags on the outer slopes of breakwater has reduced the lateral movement of breakwater and the geogrids placed in the breakwater restricted vertical movement of the same during the earthquake loadings. • The utilization of sheet piles has restricted the lateral flow of foundation soils during the mainshock. • The developed countermeasure is found to be resilient against the earthquake. [ABSTRACT FROM AUTHOR]

The present paper implements new approaches introduced in regard to pre-earthquake geo-chemical activity that results in lithosphere-atmosphere–ionosphere coupling (LAIC). Specifically, stratospheric temperature anomaly as a result of precursory atmospheric gravity wave (AGW) activity in the stratosphere is studied. A new technique is developed based on the parameters a) daily average temperature ( T mean ), b) daily maximum temperature ( T max ), c) T mean averaged over altitude, d) T max averaged over altitude. The new approach is applied to six earthquakes of Iran as well as Tohoku earthquake. Detected Anomalies are analyzed and discussed. Possible new variations such as stratospheric cooling as a result of active geomagnetic conditions are determined. Geographical maps and spatial distribution of temperature anomalies are presented to comprehend the possible source of variation. Moreover, space-based ULF emission observed by an in situ electric field detector (EFD) on board of China Seismic-Electromagnetic Satellite (CSES) is presented as associated with 3 earthquakes that occurred in 2019. Detailed analysis of satellite overpass proximity to the earthquake epicenter, earthquake magnitude, and dates are examined and ULF anomalies associated with 3 magnetic field components are discussed. Finally, a systematic approach to be implemented using the new techniques in real time is proposed. [ABSTRACT FROM AUTHOR]

To identify temporal changes in the marine reservoir effect in Northeast Japan, the radiocarbon ages of terrestrial plants and marine shells were measured from two cores obtained from Lake Harutori in Kushiro City. This lake located where one of the highest marine reservoir effect was detected in East Asia, facing the Oyashio cold current. This drilling site is situated in a tectonically active region of the southwestern Kuril arc. Based on lithological analyses, molluscan assemblages, and radiocarbon dating, we interpreted five units in order of decreasing age: basement coastal sediments, estuary sediment, laminated sediment, inner bay sediment, and artificial fills. These sediments consisted of laminated mud beds with terrestrial plant fragments and intercalating tsunami sand beds. The structure was imaged using core scanning computed tomography and X-ray fluorescence. The reservoir ages of seven pairs were obtained from estuary sediment to inner-bay sediment over the past 9000 years. [ABSTRACT FROM AUTHOR]

A series of accidents at the Fukushima Daiichi Nuclear Power Station (F1NPS), following the 11 March 2011 earthquake and tsunami, resulted in the release of radioactive substances into the ocean. In particular, the release of large amounts of radioactive caesium has damaged the fishing industry, leading to voluntary restrictions on fishing and shipping. Oceanic dispersion simulations based on estimates of the pathways and fluxes of radioactive materials provide useful information for assessing the environmental impacts and formulating measures to mitigate the effects of the accident. For the direct release rate from the F1NPS site, an estimation method was developed using the results from nearby monitoring, and the seawater exchange rate was estimated in target volume using a numerical simulation. However, the influence of volume on the seawater exchange rate was not considered. Appropriate volumes must be considered when estimating the effects of future accidents. In addition, the directional coastal transport was underestimated in the simulations of the F1NPS accident because of the low resolution. To estimate the pathways and fluxes of radioactive material to the ocean and understand the distribution of the concentration of radioactive material based on ocean dispersion simulations, a study was conducted using a higher-resolution model. The horizontal resolution of the conventional ocean dispersion model Regional Ocean Modelling System (ROMS), was increased from 1 km to 200 m. The optimal settings of the seawater exchange rate were investigated, and the radioactive caesium transport process in the coastal direction was more accurately reflected. We found that the conventional volume for determining the seawater exchange rate, including the locations of release sources and observation points, is optimal. The validity of this finding was confirmed using experimental equations from previous oceanic tracer release experiments. To estimate future release rates, it an appropriate volume must be defined, for example, depending on the distance between the locations of the release sources and the observation point. In addition, improvements in the accuracy of the simulation of the coastal transport process were observed owing to the higher resolution, which increased reproducibility. However, with a horizontal resolution of 200 m, problems with repeatability near the harbours arose. A higher resolution, achieved using nesting or other methods, would be desirable to deal with releases smaller than those in the F1NPS accident. • A higher resolution model was developed for the assessment of the Fukushima Daiichi Nuclear Power Station accident. • A method for estimating direct leakage rates using the higher resolution model was proposed for future severe accident. • The higher resolution allowed improved transport processes of 137Cs along the coast. [ABSTRACT FROM AUTHOR]

Using satellite remote sensing, we show the distribution, dominant type, and amounts of marine debris off the northeast coast of Japan after the Great East Japan Earthquake on 11 March 2011 and subsequent tsunami. Extensive marine debris was found on March 12, with the maximal amount found on March 13. The debris was found to be mainly wood (possibly lumber wood), with an estimated 1.5 million metric tons in an elongated water area of 6800 km2 (18 km E-W and 380 km N-S) near parallel to the coast between 36.75°N and 40.25°N. The amount decreased rapidly with time, with scattered debris patches captured in high-resolution satellite images up to April 6. These results provide new insights on the initial distribution of the Japanese Tsunami Marine Debris, which may be used to help find bottom deposition of debris and help refine numerical models to predict the debris trajectory and fate. Marine debris induced by the 2011 Great East Japan Earthquake and Tsunami is found to be mainly composed of wood and possibly lumber wood from constructions, with maximum amount on 13 March 2011 distributed within a narrow band of ∼18 km near parallel to the northeast coast of Japan between 36.75°N and 40.25°N. The Great East Japan Earthquake on 11 March 2011 caused a massive tsunami with a maximum height of 40.5 m. The tragic event caused thousands of lives, destroyed the Fukushima Daiichi Nuclear Power Plant, and damaged more than a million buildings. Here, we assess the distribution, dominant type, and amounts of marine debris off the northeast coast of Japan after the tsunami. The debris was found to be mainly wood (possibly lumber wood), with an estimated amount of ∼1.5 million metric tons captured in satellite imagery two days after the tsunami in an elongated water area of 6800 km2 (18 km E-W and 380 km N-S) near parallel to the coast between 36.75°N and 40.25°N. The amount decreased rapidly with time, with scattered debris patches captured in high-resolution satellite images up to 4 weeks after the tsunami. [Display omitted] • Multi-sensor remote sensing was used to map marine debris after the 2011 tsunami • The debris peaked on the second day after the tsunami, off the northeast Japan • With an aggregated area of 7.6 km2 on this day, the debris was mostly wood • Assuming an average thickness of 20 cm, the debris totaled 1.5 million metric tons • The debris lasted for 4 weeks, after which its size is below the detection limit [ABSTRACT FROM AUTHOR]

The radiocesium (137Cs) distribution between dissolved and particulate phases was examined in river water and coastal seawater as a function of the 137Cs sorption behavior on suspended particles. Dissolved 137Cs activity concentrations in the Tomioka River (salinity <0.1), about 10 km south of Fukushima Dai-ichi Nuclear Power Plant, and in coastal seawater at Tomioka fishery port (salinity >30), Fukushima Prefecture, from June 2019 to October 2021 were 3.6–20 Bq/m3 (geometric mean 11 Bq/m3) and 2.4–86 Bq/m3 (13 Bq/m3), respectively. Although the suspended particle concentration was lower in the river than in seawater, the mean 137Cs activity on suspended particles was 11,000 Bq/kg-dry in the river versus 3200 Bq/kg-dry in seawater. Proportions of ion-exchangeable, organically bound, and refractory fractions of 137Cs on suspended particles were determined by sequential extraction. The ion-exchangeable fraction accounted for 0.3–2.0% (average: 1.2%) and 0.4–1.3% (0.8%) at the river and port sites, respectively. The organically bound fraction accounted for 0.3–4.8% (1.8%) and 0.1–5.5% (2.1%) at the river and port sites, respectively. In both areas, the refractory fraction accounted for >90% of 137Cs. Therefore, the small labile 137Cs fraction on suspended particles in coastal seawater indicates that the mobility of 137Cs to marine biota is quite low. This study is the first to examine radiocesium sorption forms on suspended particles in coastal seawater near the Fukushima Dai-ichi Nuclear Power Plant. It suggests immobility of 137Cs in suspended particles being incorporated to marine biota. [Display omitted] • Cs-137 distribution between dissolved and particulate phases in river water and seawater. • Sorption behavior of Cs in suspended particle in seawater was evaluated. • Ion-exchangeable fraction accounted for only 1%. • Refractory fraction accounted for >90% of 137Cs. • Small labile fraction implies immobility of 137Cs to incorporation by marine biota. [ABSTRACT FROM AUTHOR]

[Display omitted] • Temperatures in 1,553 Japanese houses were measured in several rooms and heights. • Average vertical temperature difference of 3.1 °C was observed in the living room. • Houses in Hokkaido had the largest vertical difference of 5.1 °C in the living room. • Vertical temperature difference linked to coldness, not horizontal/temporal. • Older adults, who are vulnerable to cold temperature, were less sensitive to cold. Residents themselves are responsible for controlling their living environment, and their perception of coldness is important to protect their health. Although previous studies examined the association between perceived coldness and indoor temperature, they did not consider the spatial–temporal differences in indoor temperatures. This study, conducted in Japan, measured indoor temperatures in 1,553 houses across several rooms (living room, changing room, and bedroom) and heights (at 1 m above the floor and near the floor) over two weeks and obtained the perceived coldness from 2,793 participants during winter. Results showed substantial temperature differences between rooms (horizontal differences): 3.8 °C between living and changing rooms, and 4.1 °C between living rooms and bedrooms. The average vertical and diel (evening-morning) temperature differences in the living room were 3.1 °C and 3.0 °C, respectively. Regional analysis revealed that the Tohoku region experienced larger horizontal and diel indoor temperature differences, primarily due to its practice of intermittent and partial heating in living rooms only, in contrast to Hokkaido's approach of heating the entire house continuously. Despite Hokkaido's comprehensive heating system, it exhibited the largest vertical temperature difference of 5.1 °C in living rooms, highlighting the insufficiency of heating alone and the necessity for enhanced thermal insulation. The multivariate logistic regression analyses showed that average temperatures and vertical temperature differences were associated with perceived coldness, while horizontal and diel differences did not show a significant association, further emphasizing the importance of improved thermal insulation. Moreover, factors like individual attributes (age and gender), and lifestyle choices (meal quantity, exercise habits, alcohol consumption, and clothing amount) were significantly associated with coldness perception. Notably, older adults were less likely to perceive coldness but more vulnerable to the health impacts of low temperatures, underscoring the necessity of not solely relying on human perception for indoor temperature management to protect cold-related health problems. [ABSTRACT FROM AUTHOR]

This paper presents the new version of the operational code used at the Tsunami Warning Centers in French Polynesia and in mainland France. This nested multigrid code solves either the nonlinear shallow water or the weakly nonlinear Boussinesq equations in a spherical or Cartesian coordinates system. The objective is to simulate the propagation of tsunamis both in the context of tsunami early warning and in the context of research. The originality of this code is to simulate the tsunami propagation through a series of nested grids in which the numerical scheme is specified by the user. Three standard finite-difference methods and two finite volume schemes are available to take into account the dispersive nature of waves or to capture flow discontinuities. The performance of the five numerical schemes has been assessed through idealized 1D and 2D test cases. The convergence rate with grid refinement is evaluated for three of these tests. Diffusion and dispersion of the five schemes are evaluated through the 1D far-field propagation in a channel of constant depth. Finally, two-dimensional simulations of the 2011 Japanese tsunami are performed considering a homogeneous tectonic source. Coastal inundation is simulated in the bay of Kamaishi where run-up heights reached 10 m. The ability of the five schemes to propagate trans-Pacific tsunamis is evaluated through comparisons of time series between simulations and observations at DART buoys. In the context of tsunami early warning, numerical results show that standard finite-difference methods reproduce most of the observed time gauges and that numerical errors associated to these schemes are acceptable. • Tsunami simulation is performed both in a research and an operational context. • Three finite-difference methods and two finite volume schemes are presented. • The five numerical schemes are assessed through 1D and 2D numerical experiments. • The trans-Pacific propagation of the 2011 Japanese tsunami is simulated. • Standard finite-difference methods are acceptable in an operational context. [ABSTRACT FROM AUTHOR]

This article concerns some optimal control problems arising in the operation of drone systems to support search and rescue operations in the aftermath of disasters, such as earthquakes, floods, tsunamis, extremal weather events, among others. More precisely, we focus on issues arising in multiple drone systems to support communications and situational awareness for the planning and execution of agile and effective search and rescue operation in diverse disaster scenarios. This is of utmost importance to mitigate the impact of the destruction and, in particular, the loss of life. After describing two key operation scenarios, we point out challenges arising in communications and control, and outline a systems design framework leading to the formulation of the several optimal motion control problems that, typically, feature state constraints. Then, a Pontryagin maximum principle in the Gamkrelidze form is presented. Under certain regularity assumptions, its measure multiplier is continuous, and, thus, amenable to the formulation of effective computational algorithms based on indirect methods. Feedback control strategies to compensate for motion disturbances, on the one hand, and the optimization over multiple concatenated modes of operation - often entailing the need of different dynamic models -, on the other hand, are obtained by embedding the procedure to solve the optimal control problem in a receding horizon framework of the model predictive control type. [ABSTRACT FROM AUTHOR]

Rubble mound (RM) breakwaters are coastal structures constructed to provide tranquil condition around the port areas. After past earthquakes such as the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake, it was found that stability of breakwater not only depends on the wave action but seismic motions also play an important role for this. Very limited studies are available for the stability evaluation of RM Breakwater under earthquake motions by conducting physical model tests. To the end, an attempt has been made in the study to evaluate the stability of RM breakwater subjected to earthquake loadings. A series of shaking table tests conducted to evaluate the seismic behaviour of the RM breakwater. A prototype RM breakwater is modelled on two layers of seabed foundation soil. Different amplitudes of sinusoidal seismic motions (foreshocks and main shock) are provided at the base of the model. Later, the breakwater stability was evaluated for real earthquake motions. Various parameters such as settlement, horizontal displacement, acceleration-time histories and excess pore water pressure were measured during the tests. Deformation pattern was also studied by photos and videos captured during the tests. During the mainshock, the crown wall settled by 111 % more comparable to second foreshock; and the structure laterally displaced by more than 200 % comparable with first foreshock. The peak acceleration of input wave amplified while it was travelling from bottom to the crest of breakwater. The excess pore water pressure was maximum beneath the rubble mound, in loose sand and it was five times more during the mainshock compared to first foreshock. Due to loss in bearing capacity of foundation soil, the breakwater collapsed. Also, the effects like rolling down of armor units, densification and slumping of core material, shear deformation of breakwater body were observed during the main shock. Thus, the breakwater failed during the mainshock. Numerical analyses were also executed for both sinusoidal and real earthquake motions to make clear the mechanism of the breakwater behaviour subjected to the earthquake loadings. • The seismic responses of RM breakwater were evaluated by series of shake table tests and numerical simulations. • The increase in acceleration amplitude led to large settlements and horizontal displacements of breakwater. • The stability of model breakwater started to lose at the base, in junction between sand and breakwater as amplification of seismic wave reached maximum. • Due to development of excess pore water pressure in the foundation soils under earthquake loadings, the breakwater collapsed. [ABSTRACT FROM AUTHOR]

Ground motion prediction is an important and complex research subject in earthquake engineering and traditional approaches based on statistical regression have much room for improvement in prediction accuracy. Utilizing the 67,164 ground motion records from KiK-net and K-Net for 777 shallow crustal earthquakes between 1997 and 2019 in Japan, this paper proposes a ground motion prediction model XGBoost-SC based on the machine learning algorithm of eXtreme Gradient Boosting (XGBoost) for Japan. Magnitude, focal depth, hypo-central distance, V s30 , site altitude, and focal mechanism were used as the feature parameters, and XGBoost, Random Forest, and Deep Neural Networks (DNN) algorithms were selected for model training while Bayesian optimization was used to search for optimized hyperparameters to improve the prediction accuracy. XGBoost algorithm was selected for further study based on the comparison of results from the three algorithms. Residual change with magnitude and hypo-central distance, the probability distribution of residuals, residual standard deviation (σ), residual mean squared error (MSE), and Pearson correlation coefficient (R) were used as the evaluation parameters, and a comparison study was performed against the ground motion prediction equation based on traditional approaches. Actual earthquake events were selected to compare the prediction results against the observation records. To further validate and explain the proposed model, SHapley Additive exPlanations (SHAP) analysis was performed to explain the impact of selected feature parameters on the proposed model. The results demonstrate that the proposed XGBoost-SC model has good prediction stability for all periods, and its residual errors are smaller than those of other models. Therefore, the proposed model can better reflect the ground motion attenuation for shallow crustal earthquakes in Japan and can serve as a better model for ground motion prediction in future aseismic design and earthquake disaster mitigation efforts. • A Ground Motion Prediction Model was proposed for shallow crustal earthquakes. • The proposed model was more precise than traditional approaches. • Explained the effect of feature parameters on the prediction results. [ABSTRACT FROM AUTHOR]

The spatiotemporal evolution of seismic activity is presented for a broad region surrounding the focal areas of the 2021 M 7.3 and 2022 M 7.4 Fukushima-Oki earthquakes, which occurred within the subducting slab off the Pacific coast of Fukushima Prefecture, northeastern Japan. This study investigates the spatiotemporal variations in seismic activity during the periods before the 2021 M 7.3 earthquake, between the 2021 M 7.3 and 2022 M 7.4 earthquakes, and after the 2022 M 7.4 earthquake using the b -value of the Gutenberg–Richter relation, the aftershock decay rate (p -value), and changes in the seismicity rate (Z -value). The study area is also divided into two depth sections to investigate the depth variations in these seismicity parameters relative to the plate interface. The b -values in the deeper section (intraslab) are generally lower than those in the shallower section (around the plate interface) throughout the entire analysis period, including the hypocentral areas of the M 7.3 and M 7.4 earthquakes. The aftershock decay rates for the M 7.3 and M 7.4 earthquakes also show depth-dependent characteristics, with a slower decay rate (p < 1.0) at many grid nodes in the deeper section than in the shallower section. Furthermore, seismic quiescence was noted in the hypocentral area of the M 7.3 earthquake about two years before the occurrence of this mainshock. The locations of the M 7.3 and M 7.4 earthquakes around the down-dip edge of the slip area of the 2011 M 9.0 Tohoku earthquake suggests that the variations in seismic activity detected in this study mainly reflect stress increases due to the coseismic slip and postseismic deformation of this great earthquake. The present study suggests that the effect of viscoelastic relaxation is a dominant factor in the deeper section. Furthermore, the variations in seismicity may also reflect heterogeneous structures within the slab. • b -values in the subducting slab are mostly lower than those at the plate interface. • p -values in the subducting slab are mostly lower than those at the plate interface. • Seismic quiescence was noted in the hypocentral area of the M 7.3 earthquake. [ABSTRACT FROM AUTHOR]

Decision making in terms of travel behavior is always dynamic; however, the future behavior of an individual is often inconsistent with their present plan. Therefore, this study aims to incorporate dynamic inconsistency into the expected utility of dynamic sequential choices with a novel structural estimation approach. The incorporation of dynamic heterogeneity into expected utility enables the illustrative modeling of more types of decision making because decision making often involves dynamic inconsistent expected utilities. However, the existing approaches for dynamic discrete choice suppose an equilibrium situation and cannot evaluate these dynamic inconsistent situations. In this study, we propose a novel dynamic discrete choice model with dynamic inconsistency in its expected utility and an empirical algorithm for parameter estimation. We formulate a heterogeneous expected utility as a range constraint near the dynamic consistent expected utility for model identification. Our algorithm, which applies a mathematical program to inequality constraints, enables parameter estimation with dynamic heterogeneity. The proposed model and algorithm were applied to the problem of evacuation departure choice in the city of Rikuzentakata during the Great East Japan Earthquake and Tsunami of 2011. The case study demonstrated the validity of introducing dynamic heterogeneity via likelihood comparisons; it was also found that dynamic heterogeneity is distributed around the dynamic consistent expected utility. • Identifies a heterogeneous expected utility near the dynamic consistent one. • Employs a nonlinear optimization program with inequality constraints for estimation. • Estimates and validates the heterogeneity of perceived expected utility empirically. • Evacuees' positive future utility of non-evacuation tends to decrease over time. [ABSTRACT FROM AUTHOR]

Offshore near-fault ground motions were obtained by the DONET1 seafloor seismic network during the 2016 Off-Mie M w 6.0 earthquake that occurred in the Nankai Trough of Japan. These data provide an opportunity for exploring the characteristics of offshore near-fault ground motions, especially pulse-like ground motions. A comparison of the offshore and onshore near-fault ground motions indicates that the recorded offshore spectral acceleration (SA) in the period of 0.5–5.0 s and peak ground velocity (PGV) for this earthquake are higher than those of the onshore values, and the observed maximum spectral value (β max) of the offshore near-fault ground motions in this event is underestimated by the design spectra in the seismic codes of China, the United States, and Japan. Based on the Hilbert-Huang transform method, eight offshore pulse-like ground motion records are identified and extracted in the Off-Mie earthquake. The primary analysis indicates that the pulse-like ground motion may be caused by the directivity effect and the radiation pattern. Comparing the pulse parameters, time-frequency parameters, and response spectra of offshore and onshore pulse-like ground motions, the findings demonstrate that within the context of this earthquake event, approximately half of the offshore pulse amplitude (V p) exceeds the predicted values of onshore models; the low-frequency components of offshore pulse-like ground motions of this event are more pronounced, constituting a larger portion of the total ground motion energy; offshore pulse-like ground motions exhibit a tendency to possess higher maximum instantaneous energy (E inst) compared to onshore pulse-like ground motions with similar rupture distances. Moreover, the β max of offshore pulse-like ground motions is found to be greater than that of onshore pulse-like ground motions in medium to long periods (>0.5 s). The identified and characteristic recognition of offshore near fault pulse-like ground motion revealed by this earthquake event raises new concerns about seismic design for offshore engineering. • Amplitudes, spectra, and duration characteristics of Off-Mie earthquake are analyzed. • Eight offshore pulse-like ground motion records are identified and extracted. • Mechanisms for generation of offshore pulses for Off-Mie earthquake are explored. • Offshore pulse-like ground motion characteristics are compared with onshore values. [ABSTRACT FROM AUTHOR]

Major earthquakes occasionally cause vertiginous attacks or persistent dizziness, which may be related to the effects of autonomic stress on equilibrium function and/or psychological factors. We present the case of a 73-year-old woman who suffered from persistent dizziness for 1 year, during which she lived in a house tilted by the great 2011 Tōhoku earthquake. An electronystagmogram demonstrated leftward horizontal and downbeat nystagmus in the sitting and supine positions with eyes closed. Caloric testing and cervical vestibular-evoked myogenic potentials showed normal responses in both ears. Posturography indicated no involvement of psychological factors or autonomic stress. After moving into a new apartment, both the dizziness and nystagmus completely disappeared within 10 weeks. We speculate that the gravity-related linear acceleration with vertical and horizontal components in the tilted house may have chronically stimulated the otoliths, inducing the symptoms and nystagmus via the velocity storage mechanism. [ABSTRACT FROM AUTHOR]

The Global Positioning System (GPS) variometric approach has emerged as an attractive alternative to traditional well-developed positioning techniques including relative positioning and precise point positioning. Previous studies have demonstrated the capability of the variometric approach to retrieve coseismic displacements at centimeter-level precision, in a real-time manner using only readily available broadcast ephemeris. This study presents the first results comparing the performance of the variometric approach by using a variety of precise satellite orbit and clock products. Totally six kinds of products are included in our evaluation, namely the broadcast, IGS (International GNSS Service) ultra-rapid (predicted), ultra-rapid (observed), rapid, final (30-s clock) and CODE (Center for Orbit Determination in Europe) final (5-s clock) products. Static and dynamic experiments are conducted using 1-Hz GPS data covering a relatively large area in China during the 2008 Wenchuan M W 7.9 earthquake. After removing the linear trend, the displacements using broadcast, ultra-rapid (predicted), ultra-rapid (observed) and rapid products reach nearly equivalent precisions at centimeter level. By using final and CODE final products, the precision of displacements can be significantly improved from 1.9–2.0 cm to 0.4–0.7 cm horizontally, and from 6.0–6.2 cm to 1.0–1.7 cm vertically for the dynamic experiments. The displacements using the CODE final products achieve the best precision, improved by more than 40% compared to those using the IGS final products. With the availability of IGS high-rate real-time precise products, this approach is promising to capture coseismic displacements more precisely in real time, which is crucial for earthquake and tsunami early warning. [ABSTRACT FROM AUTHOR]

While the relationship between exchange rate risk and trading activity has been studied extensively, little attention has been paid to assessing exchange rate volatility in a travel demand model. This paper aims to examine the short- and long-run effects of real income, population, exchange rate, and exchange rate volatility on tourist flows from South Korea to Japan, Philippines, Singapore, Taiwan, and the US. To analyze the impacts of third-country exchange rate risk factors, this study takes into consideration two measures of real exchange rate volatility: the GARCH-based measure and the standard deviation of real exchange rates. The long-run results show that income growth in South Korea is driving the rising number of Korean outbound tourists, while real exchange rate has little impact on outbound tourism demand in South Korea. More importantly, the third-country effects of exchange rate volatility are found to be significant for the selected tourism destinations. An increase in third-country exchange rate risk tends to have a positive impact on Korean outbound tourism demand for the selected destinations, indicating that risk-averse Korean outbound tourists choose destinations where exchange rates are less volatile compared to destinations where they are more volatile. This study also finds evidence that Korean outbound tourists are less responsive to third-country exchange rate risk in the short run. • We examine the effects of third-country exchange rate risk on Korean outbound travel. • Real exchange rate has little impact on Korean outbound tourism demand. • Tourists are found to choose destinations where exchange rates are less volatile. • Third-country effects tend to be significant for all destinations in the long run. • Travelers are less responsive to third-country exchange rate risk in the short run. [ABSTRACT FROM AUTHOR]

The annual banded skeletons of reef corals potentially record past earthquakes events. We examined cores of five living Porites coral heads in Simeulue Island, Indonesia, near the epicenter of the 2004 Sumatra-Andaman and the 2005 Nias-Simeulue earthquakes. These sites showed 0.4–1.4 m of uplift. We measured skeletal strontium, magnesium, and calcium; carbon and oxygen isotopic ratios; and skeletal density, extension, and calcification rates, from 1994 to 2010. Coral geochemistry fluctuates more than are expected from strictly environmental causes; however, stress bands, reduced growth rates, and changed skeletal δ13C appear to reflect the tsunami and seismic uplift (the step change in skeletal δ13C results equated to 0.31 ± 0.10‰/m in response to the 2004 uplift and 0.23 ± 0.03‰/m to the 2005 uplift). [ABSTRACT FROM AUTHOR]

This paper addresses how high-frequency trading adapts to natural disasters. Stock market trades have accelerated to a rate at which shares change hands in microseconds. I examine ways in which high-frequency trading both reconfigures the dynamics of finance and changes the global financial system in different spatio-temporal ways and produces political ecologies of engagement, divergence and convergence between financial and Earth systems. Accordingly, I examine technological change and algorithmic strategies at stock exchanges. By analyzing algorithmic strategies, I investigate the connections between non-human trading and natural disasters. The analysis explains the nature of high-frequency trading strategies and market responses to three earthquakes in Japan. In the final section, I discuss how financial investment algorithms constitute a temporal informational epicenter when tectonic events are made subject to trading. [ABSTRACT FROM AUTHOR]

• Trematode prevalence and species richness decreased after the 2011 Tohoku, Japan, earthquake tsunami. • Trematode community structure also changed every year since the tsunami. • Trematode community has not fully recovered eight years after the tsunami. Trematode parasites have complex life cycles and use a variety of host species across different trophic levels. Thus, they can be used as indicators of disturbance and recovery of coastal ecosystems. Estuaries on the Pacific coast of northeastern Japan were heavily affected by the 2011 Tohoku earthquake tsunami. To evaluate the effect of the tsunami on the trematode community, we examined trematodes in the mud snail, Batillaria attramentaria , at five study sites (three sites severely exposed to the tsunami and two sites sheltered from the tsunami) in Sendai Bay for 2 years prior to and 8 years after the tsunami. While the trematode prevalence decreased at all study sites, the species richness decreased only at the sites exposed to the tsunami. Although parasitism increased over the study period post-tsunami, the community had not fully recovered 8 years after the event. Trematode community structure has changed every year since the tsunami and has not stabilised. This could be explained by the alteration of first and second intermediate host communities. Our study suggests that it will take more time for the recovery of the trematode community and the associated coastal ecosystem in the Tohoku region. [ABSTRACT FROM AUTHOR]

A significant amount of research has been conducted in Southwest (SW) Japan on climate modeling, disaster management, earthquake prediction, precise positioning, datum definition, and reference frames. However, there is substantial scope for numerical modeling and forecasting of ionospheric Total Electron Content (TEC) variations over the region, which would be beneficial for further communication and navigation purposes. Therefore, in this study we examined spatio-temporal ionospheric TEC variations using long-term Global Navigation Satellite System (GNSS) measurements from 01 January, 2011 to 31 December, 2018 through a modified Linear Time-series Model (LTM) and substantiated our findings by comparing them with those of the existing empirical Global Ionospheric Map (GIM) and Auto-Regressive Moving Average (ARMA) methods. We analyzed TEC variations at 10 permanent stations covering three districts of SW Japan, which mainly include the Kyushu district and parts of the Chugoku and Shikoku districts. To determine the performance of the LTM, the geomagnetic (Northern Polar Cap (PCN) and Disturbance (Dst)) indices were included, together with the additional solar and planetary geomagnetic disturbance indices (F10.7 and Ap). Our comparison results show that the Root Mean Square Error (RMSE) values in terms of TEC units (TECUs) between the observed and the TEC predicted by the LTM vary from 1.57 to 1.66, which are better than those between the observed and the TEC predicted by the ARMA (1.84–1.93) and the GIM (9.67–9.84) TEC models. An analysis of the results emphasizes the superior performance of the LTM over the other models in terms of its discriminability of temporal, as well as spatial, components. • LTM-TEC model was developed and validated against GIM and ARMA in SW Japan. • Model is assumed to be function of Ap, Dst and PCN indeces, not just the Ap index. • PCN Index has been used instead of the AE Index. [ABSTRACT FROM AUTHOR]

One crucial yet unanswered question about the 2011 M W 9.1 Tohoku-Oki earthquake and tsunami is what generated the largest tsunami (up to 40 m) along the Sanriku coast north of 39°N without large slip near the trench. A minimalist dynamic rupture model with wedge plasticity is presented to address this issue. The model incorporates the important variation of sediment thickness along the Japan Trench into the Japan Integrated Velocity Structure Model (JIVSM). By revising a heterogeneous stress drop model, the dynamic rupture model with a standard rate-and-state friction law can explain the GPS, tsunami, and differential bathymetry data (within data uncertainties) with minimum tuning. The rupture is driven by a large patch of stress drop up to ∼10 MPa near the hypocenter with significantly smaller stress drop (< 3 MPa) in the upper ∼10 km. The largest shallow slip reaches 75.67 m close to the trench north of hypocenter, which is caused by the large fault width, free surface, shallowly dipping fault geometry, and northwardly increasing sediment thickness, dominated by elastic off-fault response. North of large shallow slip zone, however, inelastic deformation of thick wedge sediments significantly controls the rupture propagation along trench, giving rise to slow rupture velocity (∼850 m/s), diminishing shallow slip, and efficient seafloor uplift. The short-wavelength inelastic uplift produces impulsive tsunami consistent with the observations off the Sanriku coast in terms of timing, amplitude, and pulse width. Wedge plasticity and variation of sediment thickness along the Japan Trench thus provides a self-consistent interpretation to the along-strike variation of near-trench slip and anomalous tsunami generation in the northern Japan Trench in this earthquake. • A minimalist dynamic rupture model reveals a more complete picture of the 2011 Tohoku-Oki rupture process. • Inelastic deformation of thick sediments can explain the large tsunamigenesis north of 39°N with diminishing shallow slip. • A slow rupture velocity ∼ 850 m/s in the northern Japan Trench explains the timing of the impulsive tsunami. • Sediment thickness variation along the Japan Trench plays an important role in the near-trench slip and tsunamigenesis. [ABSTRACT FROM AUTHOR]

We present a detailed description of seismic activity in Romania, Italy, and Japan, as well as the California seismic zone in the United States of America, based on the statistical analysis of the underlying earthquake networks used to model the aforementioned zones. Our results on network connectivity and simple network motifs allow for a complex description of seismic zones, while at the same time reinforcing the current understanding of seismicity as a critical phenomenon. The reported distributions on node connectivity, three-, and four-node motifs are consistent with power-law, i.e., scale-free, distributions over large intervals and are robust across earthquake networks obtained from different discretizations of the seismic zones of interest. In our analysis of the distributions of node connectivity and simple motifs, we distinguish between the global distribution and the power-law part of it with the help of maximum likelihood estimation (MLE) method and complementary cumulative distribution functions (CCDF). The main message is that the distributions reported for the aforementioned seismic zones have large power-law components, extending over some orders of magnitude, independent of discretization. All the results were obtained using publicly available databases and open-source software, as well as a new toolbox available on GitHub, specifically designed to automatically analyze earthquake databases. • Earthquake networks are treated as stationary using the full set of available data. • The connectivity distributions include a strong power-law component. • Maximum likelihood estimation is used to find the parameters of the distributions. • Three- and four-node motifs are identified in the networks of four seismic areas. • Distributions of motifs also include a strong power-law component. [ABSTRACT FROM AUTHOR]

• This study proposed an embedded concrete hinge RC column (ECH-RC). • This study proposed an ECH-RC with unbonded bar (ECH-UBRC). • ECH-RC had a Mesnager hinge embedded at the base of an RC column. • The uncertainty in the failure behavior of ECH-RC columns could be minimized. • The high-strength bars in ECH-UBRC can improve the stability of the column. In Japan, since the 2011 Tohoku Earthquake, there has been a growing interest in addressing earthquakes that exceed design assumptions. Consequently, the concept of "anti-catastrophe" has been proposed as a new approach to the seismic design of infrastructures. This approach necessitates considering the conditions after significant structural damage, a concept not explicitly addressed in current seismic design codes. This study proposes two types of reinforced concrete (RC) columns: Embedded Concrete Hinge RC column (ECH-RC) and Embedded Concrete Hinge unbonded bar RC column (ECH-UBRC) to minimize the uncertainty of failure behaviors of RC columns during Beyond Design-Basis Events (BDBE) while ensuring high ductility during Design-Basis Events (DBE). ECH-RC features a Mesnager hinge embedded at its base, while ECH-UBRC incorporates unbonded high-strength bars in addition to a Mesnager hinge. ECH-RC and ECH-UBRC are designed for bridge columns subjected to low axial loads. To ensure the stability of the entire bridge structure during BDBE, providing lateral restraints at large displacements is essential. Results from cyclic loading tests revealed that embedded Mesnager hinges effectively prevented the uncontrollable failure of RC columns during BDBE by limiting axial and shear deformation at the plastic hinge, while the unbonded bars enhanced the stability of RC columns. [ABSTRACT FROM AUTHOR]

On 21 November 2016, a Mw 6.9 intraplate earthquake occurred off the Fukushima coast in Japan, triggering a moderate-size tsunami with amplifications and long oscillations along the Sendai Bay coast. Here, we apply a hybrid approach to hindcast the wave characteristics in the Sendai Bay during the 2016 tsunami event, by analyzing coastal tide records, spectral analyses, and tsunami simulations. Our analysis shows that tsunami wave on tide stations mainly carried wave periods of 3.8–22.5 min, triggered by source periods of 18.5–22.5 min. The long oscillation in Sendai Bay was due to longer period of >28.8 min, affected by the presence of edge waves and oscillation of Sendai Bay. High-energy wave was found to be significant in most oscillation periods inside the Sendai Bay and around the Oshika Peninsula. The spatial distribution of maximum spectral and simulated tsunami amplitudes also reveal that the radiated tsunami energy was entrapped in the nearshore areas, resulting in resonance amplifications in the Sendai Bay. • Hindcast of the November 2016 Fukushima earthquake tsunami. • Local amplifications and long tsunami oscillations in the Sendai Bay. • Tsunami wave on tide stations mainly carried wave periods of 3.8–22.5 min, triggered by source periods of 18.5–22.5 min. • Long oscillations of tsunami in Sendai Bay were due to longer wave periods of >28.8 min, affected by edge waves and oscillation of Sendai Bay. [ABSTRACT FROM AUTHOR]

Atmospheric concentrations of 7Be and 10Be were investigated in Dazaifu, Fukuoka (1998–2001) and Tokyo (2002–2014) from 1998 to 2014. The seasonal variations were roughly the same for each year, with high 7Be and 10Be concentrations and high 10Be/7Be isotopic ratios caused by strong stratosphere-troposphere exchange (STE) from February to June, and fluctuating 7Be and 10Be concentrations and constant 10Be/7Be ratios caused by vertical convection in the troposphere from July to December. Using a three-box model, the residence time of the stratosphere, the troposphere, and the boundary layer were estimated to be 2 years, 55 days, and 3 days, respectively, and the mass flux observed during the STE season was estimated to be six times higher than the mass flux observed during the vertical convection season. The amplitude of solar modulation was also found to be three times larger than the amplitude of relative cosmic ray intensity at the Earth's surface. [ABSTRACT FROM AUTHOR]

• We developed an ensemble species distribution model for Japanese whiting Sillago japonica for the first time. • The model successfully predicted the habitat suitability of this species under current condition. • The potential distribution range of S. japonica will become shrinking and move northward under future climate scenarios. • Our results have important implications for future fisheries management strategies. Climate change is one of the most serious global environmental problems and it is of great importance to understand how species respond to climate change. Species distribution models (SDMs) have been regarded as an effective tool to examine the impacts of climate change on species' potential distribution. In this study, we developed a SDM for a marine fish, the Japanese whiting Sillago japonica by using records of its occurrence and five predictor variables (ocean depth, distance to shore, mean sea surface temperature, salinity, and currents velocity) and predicted its habitat suitability for current conditions and under scenarios of future climates. The SDM suggests that ocean depth, distance to shore, and temperature are the three most important predictor variables determining the distribution of S. japonica. Our SDM accurately predicted the current distribution of the species, with values of true skill statistics and area under the receiver operating characteristic curve above 0.95. Under future climate scenarios, the suitable habitat of S. japonica is predicted to become smaller in size and to shift northward. Differences between climate change scenarios for 2040–2050 and 2090–2100 showed that this species will lose more suitable habitat as climate change progresses over time. Future fisheries management strategies should take this range contraction and associated northward shift into account. [ABSTRACT FROM AUTHOR]

It's quite important to clarify what physical parameters control the magnitude of volcanic explosion to understand magma processes in the conduit. Analyses of explosion earthquakes, which are associated with vulcanian eruptions, enable us to quantitatively evaluate dynamic process of the explosive eruptions. In the present study, we analyze hundreds of explosion earthquakes recorded at Sakurajima volcano, Japan, during 2012–2013. Applying a spectral ratio method that can retrieve the source spectral information without being disturbed by heterogeneous structure to three-component seismograms recorded at three stations operated by Japan Meteorological Agency, we examine scaling relations in explosion earthquakes. To obtain an averaged feature, we group the observed explosion earthquakes into five classes (I, II, III, IV, V) according to their maximum amplitudes and calculate the spectral ratios between the five classes. Because vulcanian eruptions continue to effuse volcanic ash for several to tens of minutes, spectral amplitude ratios are calculated by shifting a time window of 10 s for five successive 10s-long time windows from the onset to coda wave. The results show that the spectral amplitude ratios are characterized by the low and high corner frequencies: about 2 Hz and 3.5 Hz, respectively. With increasing the magnitude of explosion earthquakes, amplitude ratios at low and high frequency ranges, which are 0.5–2 Hz and 3.5–10 Hz, respectively, increase, while the corner frequencies do not significantly change. Since the explosion earthquakes at Sakurajima volcano occur at a same crater without changing the vent radius, the observed spectral amplitude ratio change may be attributed to pressure changes in the conduit. Another finding is that the amplitudes of spectral ratio gradually decrease with lapse time keeping the corner frequencies. Such a lapse time dependence of spectral ratios is completely different from those of tectonic earthquakes in which direct and coda waves show a same spectral amplitude ratio. We infer that the early part of the seismic waves of explosion earthquakes is generated by an initial rapid pressure release in the conduit while coda waves are by successive oscillations of the magma system during continuous ash emission. • Lapse time dependence of spectral ratios of volcanic explosion eartquakes is completely different from those of tectonic earthquakes. • The amplitudes of spectral ratio gradually decrease with lapse time while the corner frequencies do not change significantly. • Lapse time dependence is caused by an initial rapid pressure in the conduit followed by continuous ash emission. [ABSTRACT FROM AUTHOR]

MT stations that were recorded before the moderate 5.3 M w , 2006 Sikkim Himalaya earthquake had been reoccupied after 2007 (M w 5.0) and 2011 (M w 6.9) seismic activities. We analyzed the broadband MT data (0.001–1000 s) within the 60 km radius from epicenters location and within the focal depth range of 9–30 km. The observed change in apparent resistivity in the period range of 0.001–10 s has shown a considerable post-seismic decrease of the order 10–30%. The 2D geoelectric model constructed with post seismic acquired data also reveals the feature of a decrease in resistivity (C 1). The relative change (decrease) of observed apparent resistivity ((Δρ/ρ obs) after 2006, 2007 and 2011 earthquakes find a correlation with combined stress drop 11–18.2 MPa values estimated by A rms -Δσ approach. The correlation is further strengthened by a similar change in relative apparent resistivities ((Δρ/ρ 2D_model) derived from 2D model with stress drop. Integrated stress drop values attribute to the accumulated apparent stresses (σ a = 0.23 ∆σ) that reveals the area might be subjugated to 0.6–1.2 MPa stress before 2006, 1–1.5 MPa stress before 2007 and 1.7–2.9 MPa before 2011 earthquakes occurrence. Development of micro-cracks and generation of aqueous fluids is possible due to such stressed and slow rate of relentless thrust/shear environment within the area of crust. Therefore, resistivity could have been decreased with a fluid transition from compression to dilatancy zones at different depth levels before each earthquake and further decreased upon subsequent stress drops associated with strong ground motions. We interpreted that maximum stress might be dropped in dilatational zones oblique to the maximum compression stress directions along N200E, N-S and NNW-SSE before 2006, 2007 and 2011 earthquakes and resulted in a considerable decrease in apparent resistivity along E-W (TE-mode), i.e., ρ yx component. Study area illustrated with N200E (σ 1), and NNW-SSE (σ 2) directional stress regimes along with development of micro-cracks (scattered/curved symbols), crustal fluids (grey circles) in the crust. Distribution of stress drops (red color) associated with strong ground motions (red & blue circular lines). Unlabelled Image • 10 – 30 % change in resistivity is observed before and after Sikkim Himalayan Earthquake in the period range 0.001 – 10s. • The relative change of observed apparent resistivity after the earthquakes find a fair correlation with stress drop. • Resistivity decreased with a fluid transition from compression to dilatancy zones at different depth levels before each earthquake. [ABSTRACT FROM AUTHOR]

Permeability, an important crustal property that controls transport processes in Earth's shallow crust, is known to change during large earthquakes, with significant implications on the groundwater resources and contaminant transport. Analysis of the response of groundwater in wells to Earth tides has been increasingly used to detect such changes, but often multiple interpretations of the response changes are possible, making it difficult to ascertain its hydrological implications. Here we use data from a groundwater well in North China to illustrate the use of barometric response as a method to resolve this uncertainty. The tidal response of water level in this well shows abrupt coseismic increases of both phase shift and amplitude ratio after the far-field great 2011 M w 9.1 Tohoku earthquake, which may be interpreted either as a large increase in the horizontal permeability of a confined aquifer or as an occurrence in the vertical permeability of an unconfined aquifer. Using data for the water-level response to barometric pressure we show that the aquifer was confined both before and after the Tohoku earthquake; thus the coseismic changes of the tidal response in this well are more likely to be due to an increase in the horizontal permeability. Interpretation of the tidal response shows a hereto unidentified change of poroelastic property in the far field of an earthquake, which stayed constant for ∼4 years after the earthquake until silt-cleaning in the well interrupted data collection. Thus the dynamic shaking during the Tohoku earthquake may have caused permanent deformation in the shallow crust at epicentral distances >1500 km. • The 2011 M w 9.1 Tohoku earthquake caused lasting hydrologic response in the far field. • Barometric response is used as an extra check of the post-seismic aquifer confinement. • Post-seismic hydraulic & poroelastic property changed for >4 yr in a far-field aquifer. • The earthquake may have caused permanent crustal deformation at distances >1500 km. [ABSTRACT FROM AUTHOR]

This article contributes to research on community resilience by discussing the relationship of sense of place and social capital. On 11 March 2011, Japan was struck by the Great East Japan Disaster, also known as the 3.11 disaster, which greatly damaged, if not entirely destroyed, built environments and dislocated pre-disaster community networks. Although researchers have increasingly emphasised the importance of social capital to community resilience, the reconstruction of people–place relations in post-disaster settings has remained understudied. Based on an analysis of data collected during eight months of ethnographic fieldwork on long-term recovery in Yamamoto, Japan, this article explains how locals there have renegotiated social networks and their sense of place during their temporal, spatial, and social reorientation following the disaster. Overall, the findings reveal how community resilience can be characterised by a co-constructive relationship of sense of place and social capital. [ABSTRACT FROM AUTHOR]

• Only one asperity was located in hypocenter region with large low-frequency radiation. • High-frequency radiation was located mostly at the lower periphery of the asperity. • Large high- but small low-frequency waves radiated within 2 s after the initial rupture. • Stress drop was much lower than average for global intraplate earthquakes. We studied the low- and high-frequency source processes of the 2017 Jiuzhaigou earthquake, and focused on when and where the high-frequency (2.0–10.0 Hz) seismic energy was radiated in relation to the low-frequency (0.02–0.5 Hz) seismic energy. The low-frequency source processes were jointly inverted using teleseismic P and SH broadband waves combined with near-field strong motion data. A three-dimensional model considering real topography was used to compute the near-field Green's function. The high-frequency wave radiation was inversed using the envelope of acceleration seismograms of near-field records and the empirical Green's function by the differential evolution algorithm. The results showed the 2017 Jiuzhaigou earthquake was a typical strike-slip earthquake with a seismic moment of about 6.9 × 1018 N m and maximum slip of about 1.5 m. During the 2 s following the initial rupture, the earthquake radiated large high-frequency waves but small low-frequency waves. Then, the rupture broke the high stress drop area in the up-dip direction of the hypocenter, generating an obvious asperity located just above the hypocenter. About 60% of the seismic moment of the earthquake was released during about 2–6 s after initiation of the rupture. The high-frequency radiation areas were mostly located on the lower periphery of the asperity, in accordance with the complementary relationship between the distribution of high-frequency waves and zones of large slip, which might be attributable to both the initiation of the rupture and the breaking of the high stress drop area. Parts of the high-frequency radiation areas overlapped the lower part of the asperity, where the high-frequency radiation occurred about 2 s earlier than the low-frequency radiation. The stress drop of the 2017 Jiuzhaigou earthquake was considerably lower than average for global intraplate earthquakes, but similar to that of the 2013 Lushan earthquake. [ABSTRACT FROM AUTHOR]

In the Great East Japan Earthquake of 11 March 2011, a magnitude 9.0 earthquake and accompanying tsunami struck the Tohoku region of Japan. The tsunami washed away old equipment containing polychlorinated biphenyls (PCBs) stored in the region's factories, and these PCBs may have leaked out of their casings into the marine environment. In this study, we evaluate marine PCB contamination by comparing mussels collected before (in 2005) and after (June 2011) the tsunami. PCB contamination levels were significantly elevated in mussel samples collected after the tsunami in June 2011 (3 months after the tsunami). This indicates that PCBs (specifically, formulation KC-400) leaked out of old equipment swept away by the tsunami and accumulated in mussels. PCBs were estimated to have an environmental half-life (EHL) in mussels of 4 months. Our results show that an earthquake and subsequent tsunami can cause elevated PCB contamination in the marine environment. Unlabelled Image • PCB levels in mussels increased significantly after the 2011 tsunami. • The estimated environmental half-life (EHL) of PCBs in mussels was 4 months. • PCB formulations (KC-400) leached out of capacitors swept away by the tsunami. • PCB exposure through seafood consumption was negligible. [ABSTRACT FROM AUTHOR]

Crustal movements on a millennial timescale (103–104 years) are important data for assessing the deformation of subduction zones during megathrust earthquake cycles. Such data did not exist until recently for the Sanriku coast, near the source region of the 2011 Tohoku-oki earthquake. Since the 2011 earthquake, studies of Holocene sedimentary successions have documented subsidence on the central to southern segment of the Sanriku coast on a millennial timescale, but comparable data are lacking for the northern Sanriku coast. This study derived millennial-scale crustal movements from a well-dated Holocene sedimentary succession in the Omoto plain on the northern Sanriku coast. Sedimentary and fossil evidence record the following sequence of environmental changes influenced by sea-level changes: upward growth and landward progradation of a barrier and flood tidal delta from 10,000–9000 cal BP, an estuarine environment from 9000 to 8000 cal BP after growth and progradation of the barrier and flood tidal delta ceased, and a regressive delta and subsequent fluvial environment after 8000 cal BP. Thick deposit of delta to floodplain sediment since mid-Holocene is not apparent in the Omoto plain, whereas this feature typical of subsidence area is documented along the central Sanriku coast. Although the absolute direction of the vertical deformation trend could not be well constrained in the study area because of compaction effects, the evidence indicates that subsidence during the mid and late Holocene was either absent or not noticeable on the Omoto plain. This difference in deformation histories corresponds to a contrast in coseismic subsidence during the 2011 earthquake between the northern Sanriku coast (small subsidence) and the central to southern Sanriku coast (large subsidence). The results of this study suggest that the northern and central to southern parts of the Sanriku coast should be considered separately when assessing regional crustal deformation related to subduction. [ABSTRACT FROM AUTHOR]

Abstract Concentrations of PM 2.5 in Tokyo, a densely populated megacity, often increase because of NH 4 NO 3 formation under low-wind conditions during winter. To obtain source information of NH 3 as a NH 4 NO 3 precursor, hourly NH 3 and NH 4 + concentrations were measured at an urban site in Tokyo in December 2017. Results show that PM 2.5 and NH 4 + concentrations increased simultaneously under low-wind and low-temperature conditions along with NH 3 , NOx, CO, and optical black carbon (OBC) concentrations. The remaining NH 4 + (herein, ΔNH 4 +) subtracted from observed NH 4 + to equivalent SO 4 2− concentration correlated well with NO 3 − in PM 2.5 , indicating the existence of fine NH 4 NO 3 particles. Regression analysis of hourly NH 3 + ΔΝH 4 + concentrations with CO, NOx, and OBC showed significant correlation. Virtual emission rates (VER) of NH 3 per motor vehicle in Tokyo were estimated using observed relations between NH 3 + ΔΝH 4 + and OBC, etc. with data from vehicular statistics: they were 3.7–32 mg/km. The regression of NH 3 + ΔΝH 4 + with OBC concentrations indicated an intercept of about 3.2 ppb, which is about half of the monthly average in December. This result implies that the non-vehicular source strength was nearly the same strength as the bulk vehicular emissions of NH 3 during winter in Tokyo. Highlights • Considering excess NH 4 + concentrations over SO 4 2− was useful to study urban NH 3. • Virtual emission rates of NH 3 per vehicle in Tokyo were 3.7–32 mg/km. • Non-vehicular NH 3 sources contributed almost equally to winter vehicular emissions. [ABSTRACT FROM AUTHOR]

Benthic invertebrates that inhabit the seafloor respond to anthropogenic and natural stresses, and are good indicators for assessing the benthic ecological status. We evaluated the ecosystem health of the Seto Inland Sea based on the multivariate AZTI Marine Biotic Index (M-AMBI), being its first application in a Japanese coastal sea with numerous endemic species. From the 415 locations studied, we were able to use M-AMBI in 384 sites (92.5% in all sites). The result revealed a statistically significant correlation among biotic indices including AMBI, M-AMBI, Richness, and H ' (p < 0.01). Most of the physico-chemical parameters of the sediment (water content, total organic carbon (TOC) content, sulfide content, mud content, and oxidation–reduction potential (ORP)) were significantly correlated with each other excluding sediment temperature. The M-AMBI was significantly correlated with physico-chemical variables including water content, TOC content, sulfide content, and ORP. We found that the sites classified into the organically enriched cluster, and having high contents of TOC, mud, and sulfide and negative ORP, corresponded with sites that had significantly low M-AMBI values (bad-poor ecological status). Conversely, sites in the unpolluted sandy cluster were assigned high M-AMBI values (high-good ecological status). Therefore, M-AMBI would be a useful biotic index in Japanese coasts due to the representation of the comprehensive sediment quality. • Ecological status of the Seto Inland Sea was evaluated using M-AMBI. • We evaluated the relationship of M-AMBI with physico-chemical variables. • M-AMBI values corresponded with comprehensive sediment quality. • M-AMBI can be a useful biotic index in Japanese coasts. [ABSTRACT FROM AUTHOR]

Abstract The tsunami triggered by the Great East Japan Earthquake of March 2011, the strongest quake ever recorded in Japan, deposited tsunami sediments along the coastline of the affected area. Because the sediments contained a wide variety of hazardous chemicals, including organic micropollutants, a method for rapidly evaluating the environmental and human health risks of such chemicals is necessary. For this purpose, we propose a novel three-step scheme designated "rapid screening for environmental micropollutants in emergency situations (REPE)". In the first step, samples are subjected to target screening analysis using an automated identification and quantification system (TSA-AIQS) involving gas chromatography mass spectrometry (GC-MS). In the second step, the chemicals detected by TSA-AIQS analysis are quantified precisely by conventional target analysis. The third step is risk assessment of the target chemicals. TSA-AIQS analysis of the tsunami sediments detected 63 substances, including polycyclic aromatic hydrocarbons (both native and alkylated PAHs) at high concentrations. These PAHs were precisely quantified by target analysis, and the concentrations were used to assess the health risks posed by oral intake, which were found to be negligible. Our results suggest that the REPE scheme will be useful for rapid, comprehensive screening and risk assessment in emergency situations. Graphical abstract Image 1 Highlights • Organic contaminants in "tsunami sediments" triggered by the Great East Japan Earthquake 2011 was comprehensively analyzed. • Tsunami sediments were analyzed by "rapid screening for environmental micropollutants in emergency situations (REPE)". • Samples are subjected to target screening analysis using an automated identification and quantification system (TSA-AIQS). • Chemicals detected by TSA-AIQS analysis (PAHs) are quantified precisely by conventional target analysis. • The risk of PAHs at high concentrations in tsunami sediments were found to be negligible. [ABSTRACT FROM AUTHOR]

Highlights • Ground-motion duration and spectral shape affect the seismic performance of SCBFs. • Most inside-basin ground motions caused damage states at lower spectral acceleration. • A combined intensity measure reduces uncertainty in the damage fragility functions. • Basin effects should be considered in structural design. Abstract Deep sedimentary basins are known to increase the intensity of ground motions, but this effect is not explicitly considered in the seismic design values used in the U.S. building codes. In the Pacific Northwest, the basin amplification of ground motions from subduction zone interface earthquakes is particularly important, because such earthquakes contribute significantly to the seismic hazard at natural periods for which basin amplification is high. Additionally, interface earthquakes have long durations, the effects of which are also not considered in building codes. Research into seismicity of these regions has been plentiful but few studies have evaluated the impact on the built environment. Using advanced nonlinear modeling approaches, a commonly used system, special concentrically braced frames, was studied with an eye towards comparing the performance of crustal and subduction-zone earthquakes. Using standard performance and collapse-assessment procedures, 3-, 9-, and 20-story SCBF archetypes were subjected to large-magnitude interface earthquakes recorded in basins in Japan; these motions were selected because they were recorded in locations with similar depths as the Seattle basin. The results demonstrate that deep basins in combination with the long ground-motion duration results in brace fracture at lower spectral accelerations, S a. Similarly, collapse is associated with lower values of S a. The results suggest that the strength of the archetypes inside deep basins and subjected to interface earthquakes would need to be increased by a factor of over 2.0 to ensure similar collapse probabilities as those located outside basins and/or subjected to crustal earthquake hazards. The results are similar to those obtained for other seismic resisting systems previously studied. [ABSTRACT FROM AUTHOR]

The scope of this study is to investigate the effect of the kinematic rupture process on tsunami propagation and corresponding tsunami hazards in coastal regions. It is significant for the tsunageneric earthquakes of long fault length and subsequent long duration of the fault rupture in the strike direction. Most previous studies on the tsunami hazard assessments of the Manila Trench did not consider the effect of the rupture process of huge plates. The movements of the seabed near the earthquake source are calculated by Okada model. The free surface elevation triggered by the seafloor motion is modeled by the nonlinear shallow water equations. The 2004 Indian Ocean tsunami and the 2011 Japan Tohoku tsunami are used to validate the numerical model by comparing with measurement data. The numerical experiments of the tsunami propagation for the cases of different source rupture velocities in uniform depth and continental shelf are carried out to understand the mechanism of the changes of the tsunami arrival time and the tsunami amplitude due to the kinematic rupture process. Stimulated by the long duration of plate motion of 2004 Indian Ocean tsunami, we propose several typical patterns of the rupture process of the long fault of the Manila Trench and analyze quantitatively on the role of the uncertain rupture process of tectonics source in tsunami propagation in the South China Sea. Our results have highlighted that the slow rupture velocity will remarkable affect the tsunami arrival time and maximum amplitude in the South China Sea, comparing to the instantaneous rupture. It is suggested that the rupture process is essential for assessments of the tsunami hazards generated by submarine mass failure with extreme long earthquake rupture source. • The 2004 Indian Ocean tsunami and 2011 Japan Tohoku tsunami are simulated by using the dynamic source model. • Numerical experiments depict the changes of the tsunami amplitude and the arrival time due to different rupture velocities. • The kinematic effect of the rupture process on the propagation of a virtual extreme tsunami in the Souh China Sea is investigated. [ABSTRACT FROM AUTHOR]

Abstract The response of the ionosphere to the earthquake of a moderate magnitude (M ≈ 5.9) that occurred in Japan at 11:23:50 UT on 7 July 2018 has been studied using a newly developed coherent multi-frequency radio diagnostic system for remotely probing the ionosphere at oblique incidence. The seismic activity in Japan on 7 July 2018 was accompanied by aperiodic processes in the ionosphere at distances of no less than (1–2) × 103 km from the epicentre, with an enhancement in multiple-mode propagation, and a significant Doppler spectrum broadening. Three ways of transporting disturbances from the earthquake to the changes in the character of Doppler spectra variations have been identified by examination. First, the disturbances are generated by a surface Raleigh wave launched at the earthquake epicentre. They have been ascertained in the infrasonic range (a 3- to 4-min period) of oscillations. The relative amplitude of these quasi-periodic oscillations in the electron density is equal to 1.7–9%. The duration of the oscillation trains is found to be in the range of 24–55 min. The wave disturbance speed of propagation is approximately 3 km/s. Second, wave disturbances have also been ascertained in a 15- to 30-min period range. They could be generated in the vicinity of the epicentre and then propagated as atmospheric gravity waves modulating the electron density in the ionosphere. The relative amplitude of the quasi-periodic disturbances in the electron density is equal to 14 – 34%. The wave train attains a temporal duration of about 100 min and a speed of approximately 0.3 km/s. Third, the broadening of the Doppler spectra toward negative Doppler shifts with the time delay estimated to be 49–124 min, depending on the orientation of the propagation path, is the most pronounced Doppler signature of the disturbances caused by the earthquake. This time delay corresponds to a speed of about 0.3 km/s, and consequently, it suggests that this effect most likely is caused by the atmospheric gravity waves launched at the earthquake epicentre. Apparently, the rearrangement of the ionosphere acts to reverse the sign of the Doppler spectrum shift when the atmospheric gravity waves arrive at the reflection level. Highlights • Developed coherent multi-frequency multipath radio diagnostic system demonstrated high efficiency. • Seismic activity is accompanied by aperiodic processes in the ionosphere, with enhancement in multiple-mode propagation. • Seismic activity is accompanied by significant Doppler spectrum broadening. • Wave disturbances detected in infrasonic oscillation range are generated by surface Raleigh wave. • Wave disturbances generated at epicentre propagate as atmospheric gravity waves modulating electron density. [ABSTRACT FROM AUTHOR]

Abstract Long-term slow-slip events (SSEs) and low-frequency earthquakes (LFEs) repeatedly occur in the area encompassing the Bungo Channel and Hyuga-nada region in Japan. SSEs are slow earthquake events with a duration of months to years, characterized by a type of slip that is considered transitional between the fast rupture of regular earthquakes and stable sliding along a plate interface, and have characteristics sensitive to stress states near the plate interface. In addition, since LFEs are also thought to occur at the plate interface, it would be useful to infer the stress state in this region. This study focuses on the stress-dependent characteristics of the b -values of regular earthquakes, SSEs, and LFEs, as well as the spatio-temporal relationships between b -values and these events in this area, using the Japan Unified high-resolution relocated Catalog for Earthquakes (JUICE). The b -value, which represents the relative proportion of large to small earthquakes, is inversely related to differential stress or effective stress. The b -values are moderate to low (b = 0.6–1.1) in regions with a high incidence of long-term SSEs. This spatial b -value anomaly is attributed to the partial release of accumulated stress in regions with a relatively high differential stress due to SSE activity. Furthermore, the b -value distributions estimated in this study provide constraints on the mechanisms that generate LFEs. On the other hand, the b -values increase and decrease before and during periods of enhanced LFE activity in the Bungo Channel, respectively. The increase and following decrease in b -values are thought to reflect episodes of low and high shear strength along the plate interface, which were caused by the presence of abundant slab-derived fluids under undrained conditions above the plate interface, and decreased pore pressure related to fluid depletion via LFE generation, respectively. Highlights • Stress dependent characteristics of b -values, long-term slow slip events (SSEs) and low-frequency earthquakes (LFEs) are focused in this study. • The b -values were moderate to low in regions with a high incidence of long-term SSEs, implying partial release of the accumulated stress by SSEs. • Spatial and temporal b -value distributions suggest that undrained conditions in the overlying plate play a substantial role in LFEs generation. [ABSTRACT FROM AUTHOR]

Highlights • Movement of MLT to low latitudes prior to the EQ. • Enhancements in O+ in geomagnetic equator. • Percussive effect extends from low to high latitude. • 2-day oscillation in night time peak density. Abstract Ionosphere disturbance which was seen prior to an earthquake which occurred on 11 March 2011 off the coast of Tohoku was studied. Ionosphere data which were used are: O+ density acquired with US satellite DMSP, and NmF2, h'F, and fmin obtained by ionosondes. Global Ionosphere Model (GIM) is used as side evidence to compliment findings from DMSP data and ground- based data. Although magnetic disturbance is strong during the earthquake preparation period, global survey of ground based NmF2 shows that special disturbance is limited to earthquake area. Satellite data (DMSP and GIM) analysis shows four important findings before the occurrence of the earthquake; (1) Over geomagnetic equator enhancement of O+ is found, (2) midlatitude trough (MLT) is formed before the earthquake and it moves toward lower latitude as EQ day approaches, (3) O+ enhancement at the equator side edge of the MLT, and (4) no clear difference of O+ behavior between east and west of the epicenter is identified. These four features are connected each other. Night time NmF2 at high latitude ionosonde stations such as Khabarovsk shows 2 days oscillation from 5 March and disappears on 12 March. As the latitude of the station is lower, 2 days oscillation becomes unclear, and the duration of the appearance is shorter. In order to explain both ground – based and satellite data consistently, enhanced east (west) ward dynamo electric field during daytime (nighttime) are proposed. Our speculation is that internal gravity waves of extremely small amplitude due to the ground motion interact with planetary scales waves below 10 km and is amplified. The amplified IGW propagates to the dynamo region, modifies the wind system, or conductivity, which modifies the electric field. Several observational facts which are favor to the generation of IGW are described. Finally, we stress the need of satellite constellation in order to obtain the global morphology of ionosphere disturbance and to identify the mechanism, which at least provides us the material to judge applicability to future earthquake prediction. [ABSTRACT FROM AUTHOR]

Highlights • Time lapse seismic analysis shows seabed subsidence and uplift. • Estimate a stretching of sedimentary rocks of up to 6 m at the shelf. • Indication of new faults or reactivation of faults within sediments. • Seismic velocity decreases at the shelf and increases closer to the trench axis. Abstract A detailed time lapse seismic analysis of subsurface movements is presented using seismic 2D lines acquired prior to and after the Tohoku-Oki earthquake offshore Japan in 2011. Estimated movements of the seabed from the time lapse seismic data corresponds well with estimations using bathymetric data. On the shelf, we find seabed subsidence of up to 8–9 m, and closer to the Japan trench, we find a seabed uplift of more than 10 m. Along the 100 km long 2D seismic line, we find alternating subsidence and uplift. We find horizontal displacements at the seabed that are significantly larger, up to 40–50 m, however these estimates are more uncertain. Close to the Japan trench, these horizontal displacements are practically opposite in direction (pointing towards the trench from both sides) and large (˜15 m). At the sediment-basement interface, we estimate vertical subsidence of two independent large blocks (each 4 km wide) to be up to 14 m. This means that the sediment package in this region has been stretched by 5–6 m. This type of overburden stretching is similar to hydrocarbon reservoirs that compact due to production and produce corresponding overburden stretching. Several examples of new faults, new layering and orientation of sedimentary layers are found. Implications for subsurface storage of CO 2 in areas close to subduction zones are also discussed. [ABSTRACT FROM AUTHOR]

Abstract The 2011 Great East Japan Earthquake and Tsunami caused significant changes in the morphology of the Sendai Coast, Miyagi Prefecture, Japan. These tsunami waves and the return flows resulted in the formation of concave shorelines in areas like lagoon locations adjacent to river mouths or where sandy beaches located on pre-existent (closed) river mouths were breached. This study investigates the erosion of sandy beaches adjacent to the concave shoreline at the Nanakita River mouth and the Akaiko breaching areas after the tsunami through an analysis of aerial photographs and analytical solutions of the one-line model. Soon after the tsunami, sandy beaches on both sides of the concave shoreline experienced erosion that was propagating along the coast. Analysis of the analytical solution of the one-line model indicates that the erosion propagation distance is proportional to square root of elapsed time. Measured data of erosion propagation distance from aerial photograph is found to match well with theoretical results. An approach to estimate diffusion coefficient, which is an important parameter in numerical simulation of shoreline change, is introduced. [ABSTRACT FROM AUTHOR]

Following the line of approach enumerated in the tsunami toolkit of Chagué-Goff et al. (2011), 'Expanding the proxy toolkit to help identify past events - Lessons from the 2004 Indian Ocean Tsunami and the 2009 South Pacific Tsunami, Earth Sci. Rev. 107 (1–2), 107–122', measurements of elemental and mineral magnetic properties coupled with textural parameters have been used to evaluate the 2004 Indian Ocean Tsunami (IOT) induced sediments on the Muttukadu backwaters, East Coast of India. To investigate the sediment provenance, specific Fe, Mn and Pb elemental concentrations were measured in surface sediments and compared with the previously published pre-tsunami database of backwater/inner continental shelf sediments. We found the enrichment of Fe and Pb, against depletion of Mn concentration in present tsunami sediments as compared with pre-tsunami Muttukadu sediments, reflecting the variation of the sediment source area. However, the present data of Fe and Pb enrichment and Mn depletion correlates well with continental shelf sediments hinting at sedimentary routes, processes of erosion and wave propagation. The studied tsunami deposits are characterized by dominant ∼40–85% coarse sand fractions and higher proportion of detrital low and high coercivity Fe-Ti oxides, such as magnetite, titanomagnetite and hematite, reflected by magnetic concentration (magnetic susceptibility (χ), anhysteretic remanent magnetization (ARM)) and coercivity-dependent parameters (soft isothermal remanent magnetization (Soft IRM), Hard IRM, magnetomineralogical S-Ratio and saturation IRM (SIRM)). So, it can be shown that the random spatial variability and the inverse relationship between magnetic concentration χ, ARM and SIRM parameters and grain-size ARM/χ, SIRM/χ and ARM/SIRM ratios as diagnostic criteria for the tsunami impacted the distribution of magnetic parameters in coastal backwater environments. Contrasting mineral magnetic and geochemical properties together with more sand (mean 65%) when compared with silt (mean 25%) content in tsunami sediments indicates that the area was affected by high-energy tsunami waves. The study validates environmental magnetism as a proxy, which is fast and robust for identifying the tsunami or palaeotsunami deposits. [ABSTRACT FROM AUTHOR]

Highlights • Stability of Pinus thunbergii to tsunamis was measured in two contrasting sites. • Critical turning moments with same H × DBH2 were similar in two contrasting sites. • Depth of center point of rotation was shallower at site closer to coastline. • Loading from tsunamis at 2 m height was over the critical turning moment. • P. thunbergii at site close to coastline is susceptible to tsunamis. Abstract The extent of damage to Pinus thunbergii trees in coastal forests resulting from the tsunami caused by the Great East Japan Earthquake in 2011 differed depending on the local environment. The height (H) of P. thunbergii was generally limited in stands closer to the coastline and these trees could fail due to the force of the tsunami. The resistance forces of coastal forests to tsunamis are expressed as critical turning moments and measured by tree-pulling experiments. However, few studies have focused on the differences in the critical turning moment between stands with locally different environmental conditions among P. thunbergii coastal forests. We determined the differences in the critical turning moments of P. thunbergii in two contrasting sites having different distances from the coastline. We also estimated the tolerance of P. thunbergii in the two sites against loading from tsunami. Two experimental plots, sea-side and land-side, in a coastal P. thunbergii forest were established with different depths of the water table belowground and wind forces. In both plots, the aboveground traits, including the diameter at breast height (DBH), and H × DBH2 of P. thunbergii , were positively correlated with the critical turning moments. In particular, when P. thunbergii had the same H × DBH2 between the plots, there were no differences in the critical turning moments. This result suggested that P. thunbergii at the sea-side had acclimated for 50 years to their environment by changing shallow tap roots for shallower belowground water and developing horizontal roots for strong winds. The depth of the center point of rotation was significantly deeper and was positively correlated with moments in the land-side plot, suggesting changes from a tap root system to a plate root system in the sea-side plot with a shallower water table. The estimated loading from the tsunami with a 2 m wave height was over the critical turning moments for both plots. P. thunbergii trees at the sea-side plot could be more susceptible to overturning by lower-height waves than at the land-side plot because of differences in aboveground traits of H × DBH. We propose that the practical management of coastal forests is to create an embankment by raising the ground level to develop tree growth with capable of enhanced resilience to tsunamis. [ABSTRACT FROM AUTHOR]

Abstract The 11 March 2011 M w 9.0 Tohoku earthquake, which occurred along the Japan Trench, induced an unusual shallow normal-faulting earthquake: the 11 April 2011 Fukushima-ken Hamadori earthquake (M w 6.6) near the Pacific coast in southeastern Fukushima Prefecture. Remarkable surface ruptures appeared along the NW-trending Yunodake fault, the NNW-trending Itozawa fault (west) (also known as the Shionohira fault). Although the Yunodake fault is mapped with a normal down-to-the-SW sense of slip, its paleoseismic history is not clear. A trenching survey on the northwestern part of the Yunodake fault is reported here that reveals its Holocene paleoearthquake history. The trench wall beneath the 2011 ruptures exposed fissures, open cracks, stratigraphic offsets, and a succession of cumulatively inclined Holocene sediment layers. Detailed observations of the trench walls and radiocarbon dating reveal that the two latest previous surface-rupturing earthquakes occurred between 800 and 6200 years ago and between 5900 and 6700 years ago respectively. The estimated recurrence interval of the Yunodake fault is 800 to 5900 years at this location. Highlights • The 2011 Tohoku plate boundary earthquake induced an inland 2011 Fukushima earthquake. • The 2011 Fukushima earthquake occurred on the Yunodake and Itozawa faults. • Holocene two paleoearthquakes of the Yunodake fault were documented by trenching study. • The penultimate earthquake might be simultaneous with 869 CE Jogan plate boundary earthquake. • Estimated earthquake cycle of the Yunodake fault is extremely shorter than previous evaluation. [ABSTRACT FROM AUTHOR]

Abstract Many wooden houses settled and tilted due to liquefaction during many past earthquakes. In greatly tilted houses, inhabitants felt giddy, sick and nauseous, and found it difficult to live in their houses after the earthquakes. According to a new standard announced by the Japanese Cabinet after the Great East Japan Earthquake, houses tilted at angles of more than 50/1000, of 50/1000 to 16.7/1000, and of 16.7/1000 to 10/1000 were judged to be totally collapsed, large-scale half collapsed and half collapsed houses, respectively. According to the authors' previous study on the inclination of houses, several factors affect inclination. Among them, the effect of adjacent houses was dominant during past earthquakes in residential areas. If two houses are close to each other, they tilt inward toward each other, and if four houses are close, they tilt toward their common center. The authors conducted several analyses to develop appropriate measures to prevent the liquefaction-induced inclination of existing houses. The liquefaction-induced deformation of structures can be estimated by empirical methods, static analyses (residual deformation method), and dynamic analyses. In this study, a static method called ALID was used because this method is simpler than dynamic analyses. Analyses were conducted for two possible countermeasures. One countermeasure is to lower the ground water table by placing drain pipes or shallow wells under roads. ALID analysis results showed that inclination decreases when the ground water table is lowered Highlights • Liquefaction causes settlement and the tilting of houses. • The most severe damage for inhabitants is the inclination of a house. • Adjacent houses affect the liquefaction-induced inclination of a house. • One measure to reduce the inclination of an existing house is to lower the ground water table. • Another measure is to enclose the foundation soil of the existing house with sheet piles. [ABSTRACT FROM AUTHOR]