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This study examined the relationship between risk perception and evacuation behavior, and the sociospatial contexts that affect evacuation. It is argued that risk perception and contextual conditions have a joint effect on evacuation. Data were collected from 3,756 evacuees in sixteen cities and towns affected by the 2011 Tohoku earthquake off the Pacific coast. Using geographic information systems (GIS), data from questionnaires on risk perception and activity diary surveys on behavioral response were combined with geospatial data. The main finding was that high risk perception leads to evacuation behavior, but that the difference between immediate and delayed evacuation depends on the sociospatial context. Delayed evacuation, compared with immediate evacuation, tends to occur in the following contexts: (1) the physical context (e.g., being inland at the time of the disaster impact); (2) the household context (e.g., the need to confirm the safety of household members); and (3) the social context (e.g., the need for assistance with mobility). This study extends the literature on disaster science and cognitive-behavioral geography by considering the relationship between perception and behavior in urban spaces in emergencies. The findings are relevant to the development of disaster preparedness planning to minimize human losses. [ABSTRACT FROM AUTHOR]

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]

The underlying mechanism of the ongoing seismic swarm in the Noto Peninsula, Japan, which generates earthquakes at 10 times the average regional rate, remains elusive. We capture the evolution of the subsurface stress state by monitoring changes in seismic wave velocities over an 11-year period. A sustained long-term increase in seismic velocity that is seasonally modulated drops before the earthquake swarm. We use a three-dimensional hydromechanical model to quantify environmentally driven variations in excess pore pressure, revealing its crucial role in governing the seasonal modulation with a stress sensitivity of 6 × 10-9 per pascal. The decrease in seismic velocity aligns with vertical surface uplift, suggesting potential fluid migration from a high-pore pressure zone at depth. Stress changes induced by abnormally intense snow falls contribute to initiating the swarm through subsequent perturbations to crustal pore pressure. [ABSTRACT FROM AUTHOR]

As North Korea emphasized its "second mission," the reunification of the two Koreas, with its nuclear weapons, South Korea has been mobilizing all potential resources to deter North Korea's attempt. Indeed, it rapidly improved its relations with Japan as well as strengthened the U.S. extended deterrence through the "Washington Declaration" in early 2023. The United States, South Korea, and Japan even initiated their trilateral summit meeting to discuss their combined deterrence posture against North Korea. This article evaluates South Korea's current nuclear preparedness, including preemptive/preventive strikes, missile defense, and civil defense, identifies weaknesses, and analyzes whether Japan can mitigate the weakness. [ABSTRACT FROM AUTHOR]

Three-dimensional finite-element models, which can handle the stress perturbations caused by subsurface mechanical heterogeneities and fault interactions, have been combined with the finite source inversion to estimate the coseismic slip distribution over the fault plane. However, the mesh grid for discretizing the governing equations in the finite-element model significantly affects the numerical accuracy. In this study, we performed kinematic finite source inversion with idealized (regular observation point array; M1A–M1D) and regional (GEONET, GPS Earthquake Observation Network System stations in Japan; M2A–M2H) models with different mesh sizes to quantitatively analyse the effect of the mesh grid size around the fault plane on the inverted fault slip distribution. Synthetic observation data vectors obtained from the finest models (M1A and M2A) are compared with those from the coarser models (M1B–M1D and M2B–M2H), which were adopted to construct Green's function matrix. We found that the coarser mesh models derived a smaller surface displacement, leading to a decrease in the norm of Green's function matrix, which in turn influences the fault slip magnitude from the finite source inversion. Finally, we performed the source inversion for the fault slip distribution of the 2011 M w 9.0 Tohoku–Oki earthquake using the coseismic surface displacements recorded at the GEONET and seafloor stations and finite-element modelling. By reducing the mesh size on the fault, we confirmed that the estimated magnitude of fault slip converged to approximately 80 m, which is consistent with the range of fault slip amounts from previous studies based on the Okada model. At least 0.88 million total domain elements and a 6.7 km2 mesh size on the fault plane with an area of 240 × 720 km2 are required for the convergence of the fault slip. Furthermore, we found that the location of the maximum fault slip is less sensitive to the mesh size, implying that source inversion based on a coarse mesh model (i.e. less than 0.5 million elements and > ∼60 km2 mesh size) can quickly provide the rough fault slip distribution. [ABSTRACT FROM AUTHOR]

In this study, the atmospheric changes for the 9.0-magnitude Tohoku earthquake, which occurred on March 11, 2011, are analyzed. The March 11, 2011 earthquake was preceded by a large foreshock on March 09, 2011 with magnitude M 7.3 and depth 32 km at 02:45:20 UT near the east coast of Honshu, Japan. The earthquake doesn't limit its effects on the Earth's lithosphere, hydrosphere and biosphere; it also extends its effects to the atmosphere because of the gas emissions, which produce large-scale seismic waves from the ground and release gases into the atmosphere. In this study, the anomalies of the atmospheric parameters are studied by using one of the atmospheric models from the Naval Research Laboratory Mass Spectrometer Incoherent Scatter Extension 2000 (NRLMSISE-00) model data to analyze the atmospheric anomalies of the Tohoku Earthquake on March 11, 2011. The atmospheric parameters of atomic oxygen (O), hydrogen (H), atomic nitrogen (N), helium (He), argon (Ar), molecular oxygen (O2), molecular nitrogen (N2), total mass density (ρ), neutral temperature (Tn), exospheric temperature (Tex) and anomalous oxygen (AO) are used for analysis during the earthquake occurrence. The epicenter of the Tohoku earthquake, with a geographical location of latitude 38.30° N and longitude 142.37° E, is used for the NRLMSISE-00 model as input parameters to analyze the output of atmospheric parameters. To compare the atmospheric changes caused by the earthquake, 5 days before and after the earthquake are considered. To detect where the atmospheric parameters increased or decreased from the earthquake day, the percentage deviation of the NRLMSISE-00 model is applied. The results indicate that there were atmospheric parameter anomalies that occurred a few days before, following and during the earthquake on March 11, 2011. Except for hydrogen (H), all atmospheric parameters average daily percentage deviation values were positive during the 5 days before and after with respect to the main earthquake shock on March 11, 2011. The NRLMSISE-00 model can capture the atmospheric parameter anomalies of the Tohoku earthquake well. [ABSTRACT FROM AUTHOR]

Changes in deviations from the background values of the parameters of the sporadic E ionosphere (Es) are studied: the effective (virtual) height h'Es and limiting reflection frequency (foEs). Basically, the analysis was carried based on hourly measurement data from several Japanese ground stations for vertical sounding of the ionosphere in order to identify possible short-term ionospheric earthquake precursors with intermediate (from 60 to 300 km) hypocentral depths. All known events (12 earthquakes, from 1969 to 2022) are considered for which the necessary ionospheric data in the Japan region and magnitudes (M) ranging from 6.5 to 7.6 are available. From coincidence of the maxima in changes in the considered Es characteristics on the same day at pairs of stations separated by hundreds of kilometers, the time of appearance of possible ionospheric earthquake precursors was recorded. According to the ionospheric data available during the preparation period for the studied earthquakes, a tendency has been identified according to which the time the moment of the main influence is anticipated depends on the magnitude of the impending earthquake. Similarities and differences in the responses of the ionosphere to the preparation of surface (crustal) earthquakes and earthquakes with an intermediate hypocentral depth are revealed. Another tendency is also revealed: earlier appearance of the identified earthquake precursors with increasing hypocentral depth for earthquakes with an intermediate hypocentral depth at the same distances from the epicenter to the observation point. [ABSTRACT FROM AUTHOR]

Inversion tectonics, in which old normal faults act as reverse faults in current stress fields, are frequently observed in northeastern Japan (Tohoku District); however, the conditions that control these fault activities remain unclear. To improve the identification of faults that are more favorable to slip under current stress conditions, the regional fault mechanisms in the Tohoku District must be better understood. The stress field in the Tohoku District and the likelihood of fault activities were thus estimated using slip tendency (ST) analysis. The results show that in the eastern margin of the Japan Sea (EMJS), the reverse fault type is dominant in the stress field. The maximum horizontal direction changes clockwise from E–W to NW–SE from the northern to the southern regions and counterclockwise from NW–SE to E–W from the Japan Sea to the inland area. In the Tohoku inland area, the estimated direction of the maximum horizontal axis changed after the 2011 Tohoku-Oki earthquake, from E–W to WNW–ESE. ST values were calculated for seven events in the EMJS area. To avoid the influence of the Tohoku-Oki earthquake, only stress field data prior to the 2011 Tohoku-Oki earthquake were used to determine ST values for four of the events in the Tohoku inland area. The results showed eastward-dipping fault planes with low dip angles (approximately 30°–45°) and large ST values (approximately > 0.7). The large ST values indicate that the stress field fault is favorable to slip and the results were consistent with the actual fault plane in the EMJS area. However, in the Tohoku inland area and the southern part of fault model of the 1993 Hokkaido Nansei-Oki earthquake, fault planes with large ST values were found to be inconsistent with the slipped fault plane, thus indicating that slipping was unfavorable. The regional differences are consistent with the volcano distribution and thus, the fluid supply from volcanic activity may have helped the fault slip under difficult stress conditions. [ABSTRACT FROM AUTHOR]

The present study investigates the effectiveness of design strategies that induce yielding in the substructure of a single-layer latticed roof. The roof has a span of 28.9 m and a half-open angle of 30°. It is supported by a ductile substructure consisting of buckling-restrained braces (BRBs), and the substructure is designed to initiate yielding under a base shear coefficient of 0.40. The responses are analyzed using artificial earthquake motions corresponding to Chinese and Japanese design acceleration response spectra. The responses demonstrated that the dynamic amplification within the roof is considerably suppressed in comparison with a roof supported by elastic substructures. The negligible variance in the roof responses to the Japanese and Chinese spectra is also illustrated, suggesting the potential for reciprocal applicability of research results. [ABSTRACT FROM AUTHOR]

Numerous studies have reported that surface hydrological loading can seasonally modulate seismicity rates at crustal depths. For example, substantial winter snow accumulation occurs across the Japanese Islands, and these snowy regions appear to have seasonally modulated the occurrence of previous large inland earthquakes. Therefore, it is important to investigate the impact of seasonal stress changes on crustal seismicity to deepen our understanding of earthquake generation. Here we constrain seasonal changes in the surface load across northeastern Japan using Global Navigation Satellite System surface displacements and evaluate the potential relationship between temporal trends in inland seismicity and estimated seasonal stress changes. The spatial distribution of the seasonal surface load is consistent with snow depth along the Sea of Japan. The inland seismicity beneath northeastern Japan is modestly modulated by the seasonal stress changes that are induced by the annual snow load. However, this seasonal response is weaker than that in other regions. This weak modulation may be due to the small surface‐load‐induced stress perturbation relative to the long‐term‐averaged stressing rate and/or the limited presence of crustal fluids to trigger seismicity in Japan. Plain Language Summary: The number of earthquakes can be seasonally controlled by surface processes, such as snow accumulation and melt. Therefore, it is important to estimate the temporal stress changes where earthquakes occur to clarify the role of surface processes in the timing of earthquake occurrence. Here we estimate seasonal changes in surface mass from a dense array of surface displacement observations across northeastern Japan and compare the timing of shallow earthquake occurrence with the stress changes induced by the estimated surface mass. The estimated seasonal surface mass can be explained using snow depth observations along the Sea of Japan. The seasonal stress changes induced by the snow appear to weakly control the number of earthquakes in northeastern Japan. The reason why the number of earthquakes does not vary much seasonally may be because the seasonal stress changes are small compared to the long‐term stressing rate. Key Points: The spatial distribution of seasonal surface load across northeastern Japan is estimated using Global Navigation Satellite System displacement observationsThe stress amplitude induced by the estimated seasonal surface load modestly modulates the inland seismicityThis weaker modulation may be due to smaller stress change perturbations and the lower likelihood of unclogging saturated fractures [ABSTRACT FROM AUTHOR]

Earthquake swarms are most commonly composed of small‐magnitude earthquakes. However, a recent study by Yoshida, Uchida, et al. (2023, https://doi.org/10.1029/2023GL106023) analyzed a swarm beneath the Noto Peninsula in Japan that, after more than two years of moderate‐magnitude seismicity, triggered the moment magnitude (Mw) 6.2 Suzu mainshock in May 2023. Based on high‐precision earthquake locations and a slip inversion of the mainshock, these authors found that the Mw 6.2 Suzu earthquake occurred on the updip extension of a fault that was active during the swarm, likely driven by increased fluid pressure. After publication of that paper, a much larger and more destructive Mw 7.5 event occurred nearby on 1 January 2024. These events underscore the potential for swarms to be precursors to large, damaging earthquakes. Forecasting the eventual evolution of swarms is currently very challenging but could be aided in the future by new observations and models. Plain Language Summary: Although earthquake swarms often only contain small earthquakes, occasionally they can trigger large, damaging earthquakes. Yoshida, Uchida, et al. (2023, https://doi.org/10.1029/2023GL106023) examined the triggering of a magnitude 6.2 earthquake in Japan, which caused extensive damage, following two years of smaller earthquakes. This sequence, like many swarms, may have been driven by elevated fluid pressure migrating upwards within the crust. After publication of that paper, a much larger and more destructive Mw 7.5 event occurred nearby. Forecasting the eventual evolution of ongoing swarms is currently very challenging but could be aided in the future by new observations and models. Key Points: Earthquake swarms can be precursors to damaging earthquakes, including the 1 January 2024, Mw 7.5 Noto Peninsula, Japan eventFluid pressure changes often drive swarm activity, and their degree of confinement may influence swarm evolutionDirect observations of fluids in fault zones combined with numerical modeling may aid swarm forecasting in the future [ABSTRACT FROM AUTHOR]

This study delves into the interplay of Rayleigh wave‐groundwater‐aquifer dynamics, utilizing seismic data from designated stations, particularly the magnitude 9 event on March 11, 2011 (02:46:23 PM epicenter), Tohoku earthquake, Japan. Auto spectra uncover significant peaks, linking groundwater level with the vertical motion of Rayleigh waves. High coherence between groundwater levels and seismogram vertical displacements confirms this connection. Coherence analysis validates it at the significant frequency bands. Groundwater storage coefficient estimation aligns with typical values of confined aquifers, ranging from 1.0E‐05 to 1.0E‐03. This consistency applies across different methods and other earthquake events, highlighting seismic impact. The findings enhance understanding of aquifer behavior during seismic events, aiding groundwater management and earthquake readiness in susceptible regions. Further research should expand datasets for coefficient accuracy. Insights advance aquifer behavior comprehension during seismic events, guiding groundwater management and earthquake readiness in prone areas. [ABSTRACT FROM AUTHOR]

The Fukushima power station in Japan was affected by a major earthquake and tsunami in March 2011, inspecting the primary containment vessel remains difficult due to high radioactivity. Long-reach robot arms are useful in inspecting such hazardous environments, and a coupled tendon-driven mechanism enables realizing a long, light-weight, and thin manipulator. However, high elastic elongation of tendons due to gravity may lead to unstable joint control. In this paper, we introduce dynamics-based control as a feasible strategy for a long-reach tendon-driven robotic arm. Additionally, a planning method to identify the joint angle path ensuring stability is proposed. Considering stability analysis, the potential due to the tendon elasticity and gravity is evaluated and used as an index of joint stability. The rapidly exploring random tree is used as the planning algorithm. The effectiveness of the proposed method was demonstrated through the successful manipulation of a 5-kg payload by a 10-m long robotic arm. [ABSTRACT FROM AUTHOR]

To monitor the volcanoes at a high spatiotemporal resolution, we introduce the singular value decomposition‐based Wiener filter and the three‐component waveforms in ambient noise velocity monitoring. The continuous ambient noise data from 63 stations around Mt. Fuji and Mt. Hakone, Japan, during the January‐September 2011 were analyzed to estimate the seismic velocity variations at a 1‐day temporal resolution, allowing us to distinguish the velocity drops caused by the 2011 Mw 9.0 Tohoku‐oki and the Mw 6.0 East Shizuoka earthquake. The velocity drop during the Tohoku‐oki earthquake was large in volcanic areas and was larger around Mt. Hakone than Mt. Fuji. This difference is possibly due to the existence of fluid‐ and gas‐rich zones at shallower depths and a higher crack density around Mt. Hakone. In addition, the velocity drop at Mt. Fuji during the Tohoku‐oki and the East Shizuoka earthquake was the same level, despite larger static stress changes beneath Mt. Fuji during the East Shizuoka earthquake. We interpret this inconsistency between the velocity drops and static stress changes to arise from incomplete recovery of the generated cracks during the Tohoku‐oki earthquake when the East Shizuoka earthquake occurred. This study also investigates the spatial variations in recovery speed and recovery amount, finding slow recovery speeds in the volcanic areas and fault areas, possibly due to larger crack densities in the crust. Furthermore, we observe the lowest velocity recovery amount in the volcanic areas, which is likely attributed to the maintained increase in pore pressure due to the volcanic gas bubbles. Plain Language Summary: Ambient noise monitoring is a useful tool to estimate the dynamic behaviors of subsurface conditions, such as crustal stress and pore pressure. In recent years, this monitoring technique has been applied to volcanic eruption prediction, however, the temporal resolution is about 5 or 10 days, which is still insufficient for volcanic eruption prediction. Therefore, we introduce denoising techniques with combination of singular value decomposition and Wiener filter to stably estimate the velocity change in high temporal resolution. As a result, we are able to estimate velocity changes with 1‐day temporal resolution and distinguish the velocity changes caused by the 2011 Mw 9.0 Tohoku earthquake and the Mw 6.0 East Shizuoka earthquake that occurred 4 days after the Tohoku earthquake. The high temporal resolution of this monitoring approach could contribute to volcano monitoring systems, particularly through providing additional information on the state of the volcanic system. Moreover, we model the velocity changes and estimate the spatial variation of recovery speed and recovery amount, which is important to predict the postseimic recovery of velocity changes. We found slow recovery speed in volcanic areas and fault areas, and small recovery amount in volcanic areas. Key Points: Ambient noise monitoring with high temporal resolution (1 day) was applied to volcanic areas (Mt. Fuji and Hakone area)Slow velocity recovery speeds in the volcanic areas and fault areas, possibly due to larger crack densities in the crustThe lowest velocity recovery amount in the volcanic areas could attribute to the maintained high pore pressure due to the volcanic gas [ABSTRACT FROM AUTHOR]

Qian Daosun (1887–1966) was imprisoned for collaborating with the Provisional Government in North China under Japanese occupation, and to this day he is labelled as hanjian (traitor). Yet, Qian was first and foremost a cultural literatus, librarian, and an exceptional translator with an in-depth understanding of Japanese culture and languages. This article examines the crucial role that Japan and the Japanese language played for Chinese cultural literati in their quest to save China. It also brings to the forefront the dilemmas and agonizing choices Qian faced in his attempt to promote Sino-Japanese cultural exchange in the midst of war, in particular as a librarian. Wartime libraries are highly contested sites of selection, destruction, censorship, preservation, confiscation, and knowledge production. An added layer of complexity was Japan's cultural policy in China that promoted Japanese-language collections and governed libraries such as the Beijing1 Modern Science Library where Qian worked. What exacerbated Qian's dilemmas was his upbringing, which led him to form close personal connections with like-minded Japanese literati. Lastly, this article revisits the hanjian label by comparing Qian's fate to that of other librarians and returned students of Japan, such as May Fourth writer Lu Xun and patriotic bibliophile Zheng Zhenduo. By deliberately examining May Fourth writers alongside hanjian and Japanese intermediaries, the intention is to dismount arbitrary labels and divisions that have set them apart and against each other in the resistance versus collaboration dichotomy. [ABSTRACT FROM AUTHOR]

Space is a feature of all disasters, and it is through decisions on how space is developed, used, and reproduced that disasters manifest themselves. Critical urban theory sees urban space—cities—as an arena of contestation expressed through the relationship between people, power, and the built environment. Cities allow for an unpacking of this process of contestation through the interpretation of various temporal, spatial, social, and physical elements that together create complex issues and 'wicked problems'. In these urban spaces in all their complexity, disasters reveal both the worst injustices and inequalities present in a society. By drawing on three well‐known cases—Hurricane Katrina in 2010; the Haiti earthquake in 2010; and the Great East Japan Earthquake and Tsunami in 2011—this paper not only explores the opportunities that critical urban theory presents for gaining a deeper understanding of disaster risk creation, but also it encourages disaster scholars to engage with it. [ABSTRACT FROM AUTHOR]

Background: In this article, we review and discuss the photoprotection behavior of Asians based on the literature, along with a subanalysis of an original online survey, and make recommendations to optimize photoprotection for Asian populations to prevent photoaging and pigmentary disorders. Methods: An international panel of eight dermatologists from Asia (China, Korea, Japan, Singapore, Indonesia, and Vietnam) met to discuss sunscreen photoprotection for Asian patients. Additionally, a subanalysis of an online survey by 3000 respondents from three Asian countries (China, Indonesia, and Japan) investigated general public awareness and attitudes to sun exposure. Results: A pre‐meeting survey of the eight experts from Asia showed key concerns of Asian patients consulting dermatologists are pigmentary disorders, especially actinic/senile lentigo, post‐inflammatory hyperpigmentation, melasma, vitiligo, and Hori's nevus. The survey subanalysis of participants from China, Indonesia, and Japan with predominantly Fitzpatrick skin types (FST) II to IV revealed that they are particularly concerned about sun exposure causing photoaging and pigmentary disorders. Most of the respondents indicated they have limited knowledge on sunlight radiation and appropriate sunscreen protection factors. Only 22%, 13%, and 3% for China, Indonesia, and Japan, respectively, systematically use multiple protective measures (using sunscreen, avoiding midday sun, staying in the shade, wearing a hat, protective clothing, and sunglasses) when exposed to the sun. Conclusions: Further education is needed for Asian populations on the importance of comprehensive daily photoprotection, including broad‐spectrum sunscreen, with high UVA and visible light protection, to reduce and prevent photoaging and pigmentary disorders. [ABSTRACT FROM AUTHOR]

Motivated by the generation of exceptionally large gravito-elastic waves during the Hunga Tonga–Hunga Ha'apai explosion of 15 January 2022, we examine theoretically the nature of the main air wave branch G R 0 , whose undispersed celerity, ∼ 313 m/s, suggests that it may represent a "tsunami" of the atmospheric column for an effective thickness H eff ≈ 10 km. However, we find that its potential energy is about 90% elastic across a wide frequency band, thus negating the widely held perception that it constitutes an oscillation between kinetic and gravitational energy. Based on the systematic study of the effect of finite compressibility on the dispersion and potential energy of a classic oceanic tsunami, we confirm that this feature of the branch G R 0 stems from the similarity between its celerity and the average speed of sound in the atmosphere. We then show that this similarity is not fortuitous, but rather expected for a perfect gas, which, we conclude, cannot sustain "tsunamis", i.e., oscillations between kinetic and gravitational energy. [ABSTRACT FROM AUTHOR]

On March 18, 2011, one of Germany's most famous children's book authors, Gudrun Pausewang (1928-2020), publicly spoke about the connection between 3/11 and her award-winning 1987 classic, Fall-Out (Die Wolke). I posit that Michaël Ferrier's texts with a 3/11 theme highlight the synchronic as well as diachronic dimensions of the Great East Japan Disaster and therefore go far beyond Pausewang's 1987 approach to think globally about nuclear energy and technological risk scenarios. While Pausewang's novel focuses on the tragic experience of a young adult who copes with the aftermath of a nuclear accident in Germany in the 1980s, Ferrier strategically reveals the complexities of knowledge and uncertainty in the wake of environmental and human catastrophe as an on-going crisis or déjà-vu of Chernobyl and Hiroshima. My analysis explores Ferrier's (re)mediation of the convolution of this crisis across various media, including documents of popular culture, by insisting on the thematic and structural connections between his texts with a 3/11 theme, Pausewang's 1987 novel, and two German adaptations of Pausewang's novel, Gregor Schnitzler's 2006 drama film, Die Wolke, as well as a Anike Hage's 2008 graphic novel. Ferrier's works unapologetically reveal elisions that have occurred in mediated disaster narratives across borders. [ABSTRACT FROM AUTHOR]

We investigate spatiotemporal changes of intermediate‐depth earthquakes in the double seismic zone beneath Central and Northeastern Japan before and after the 2011 magnitude 9 Tohoku earthquake. We build a template‐matching catalog 1 year before and 1 year after the Tohoku earthquake using Hi‐net recordings. The new catalog has a six‐fold increase in earthquakes compared to the Japan Meteorological Agency catalog. Our results show no significant change in the intermediate‐depth earthquake rate prior to the Tohoku earthquake, but a clear increase in both planes following the Tohoku earthquake. The regions with increased intermediate‐depth earthquake activity and the post‐seismic slips following the Tohoku earthquake are spatially separate and complementary with each other. Aftershock productivity of intermediate‐depth earthquakes increased in both planes following the Tohoku earthquake. Overall, aftershock productivity of the upper plane is higher than the lower plane, likely indicating that stress environments and physical mechanisms of intermediate‐depth earthquakes in the two planes are distinct. Plain Language Summary: Intermediate‐depth earthquakes occur at 70–350 km depth below the Earth's surface. Because of the high pressure and temperature at such depths, the physical mechanism of intermediate‐depth earthquakes is still poorly understood. In this study, we try to obtain insights into this problem by investigating the behaviors of intermediate‐depth earthquakes before and after the 2011 magnitude 9 Tohoku earthquake. We build an intermediate‐depth earthquake catalog in Central and Northeastern Japan around the Tohoku earthquake. This new catalog contains six times more earthquakes and is more complete than the standard catalog used in previous studies. After analyzing the earthquakes from the new catalog, we find no significant precursory acceleration of intermediate‐depth earthquake activities prior to the Tohoku earthquake. However, we observe a clear increase in intermediate‐depth earthquake rate following the Tohoku earthquake. We also observe that the aftershock productivity of intermediate‐depth earthquakes increased following the Tohoku earthquake. The subduction slab beneath our studied area is characterized by a double seismic zone, and we find that aftershock productivity in the upper plane of seismicity is higher than that in the lower plane. This phenomenon may be due to differences in the environments or physical mechanisms in the two planes of intermediate‐depth earthquakes. Key Points: We build a new catalog of intermediate‐depth earthquakes in Japan 1 year before and 1 year after the 2011 M9 Tohoku earthquakeThere is no significant increase in intermediate‐depth earthquake activities prior to the Tohoku earthquake but a clear increase after itAftershock productivities of double seismic zones increase after the Tohoku earthquake, and it in upper plane is higher than in lower plane [ABSTRACT FROM AUTHOR]

We examined whether pre-disaster Sense of Coherence (SOC) mitigated the impact of housing damage on health and well-being of older survivors after the 2011 Japan Earthquake and Tsunami. A panel survey was conducted in a city located 80 km west of the epicenter seven months before and three years after the disaster (3594 respondents). Among respondents with lighter property damage, higher SOC was inversely associated with mental distress (coefficient − 0.29, 95% CI (confidence interval) − 0.39, − 0.19, p <.01), unhappiness (coefficient − 0.33, 95% CI − 0.43, − 0.23, p <.01), low expectation of mutual help (coefficient − 0.17, 95% CI − 0.27, − 0.07, p <.01), and weak community attachment (coefficient − 0.20, 95% CI − 0.30, − 0.11, p <.01). Conversely, among those who experienced housing loss, higher SOC was no longer protectively associated with health and well-being. Loss of generalized resistance resources due to serious damage led to difficulties in stress coping. [ABSTRACT FROM AUTHOR]

Crustal earthquakes are generally recognized as having recurrence periods of more than 1000 years. However, in northern Ibaraki Prefecture, Japan, two moderate-sized earthquakes occurred on almost the same fault plane in 2011 and 2016. Moreover, it has been reported that the slip distributions derived from crustal deformation data from these two events are almost identical. We performed a near-field waveform inversion analysis to estimate the details of the spatiotemporal distribution of the co-seismic rupture. Our results reveal large slip areas during each earthquake at different locations across the bend of the fault plane. These results indicate that the shear stress of the fault area where the main slip occurred during the 2011 event was not rebuilt in such a short period, a phenomenon that had not previously been discussed for this sequence. Our results also suggest that the fault geometry affected such complex fault ruptures. [ABSTRACT FROM AUTHOR]

The article discusses the 1st Joint Workshop on the A3 Foresight Program, which brought together climate and environmental scientists from South Korea, China, and Japan to share research on climate change, extreme weather events, aerosol-climate interactions, and the socioeconomic impacts on communities in Northeast Asia. The workshop aimed to reactivate international collaborations that were disrupted by the COVID-19 pandemic and highlighted the need for improved understanding and prediction of climate behavior in the region. The article also discusses studies on climate changes, monsoon dynamics, aerosol concentrations, and the socioeconomic impacts of climate change on Northeast Asian communities. The workshop was successful in fostering international networking and will be followed by a second workshop in China. [Extracted from the article]

The objective of this study was to examine co- and post-seismic deformation following the 2011 M w9.0 Tohoku–Oki earthquake and its impact on Northeast Asia. Large-scale, long-term post-seismic deformation caused by the earthquake was extracted according to the continuous Global Navigation Satellite Systems (GNSS) observation data for Japan, South Korea, Northeast China and the Far East Russia. The present research adopted a 2-D viscoelastic model to simulate the observed large-scale seismic deformation, considering the subducting slab in the western Pacific. The duration of the after-slip in the northwest of the main rupture area was found to be greater than that in the south of the main rupture area (approximately 6 yr). The steady-state viscosity coefficient of the continental mantle was found to be 8 × 1018 Pa·s. Post-seismic deformation in Northeast Asia was primarily caused by viscoelastic relaxation of the mantle, and observations on the west side of the Tan-Lu fault were smaller than simulation, revealing the heterogeneity in viscosity structures in NE China. [ABSTRACT FROM AUTHOR]

For more than a decade, GRACE data have provided global mass redistribution measurements due to water cycles, climate change and giant earthquake events. Large earthquakes can yield gravity changes over thousands of kilometres from the epicentre for years to decades, and those solid Earth deformation signals can introduce significant biases in the estimate of regional-scale water and ice mass changes around the epicentres. We suggest a modelling scheme to understand their contribution to the estimates of water and ice mass changes and to remove the earthquake-related solid mass signals from GRACE data. This approach is composed of physics-based earthquake modelling, GRACE data correction and high-resolution surface mass change recovery. In this study, we examined the case of the 2011 Tohoku–Oki earthquake to better estimate the regional sea level and hydrological mass changes in the East Asia. The co- and post-seismic changes from GRACE observations were used to constrain the earthquake model parameters to obtain optimal self-consistent models for the earthquake source and the asthenosphere rheology. The result demonstrated that our earthquake correction model significantly reduced the mass change signals by solid Earth deformation from the time-series of regional surface mass changes on both land and oceans. For example, the apparent climate-related ocean mass increase over the East Sea was 1.59 ± 0.11 mm yr−1 for 2003–2016, significantly lower than the global mean ocean mass trend (2.04 ± 0.10 mm yr−1) due to contamination of the earthquake signals. After accounting for the solid mass changes by the earthquake, the estimate was revised to 1.87 ± 0.11 mm yr−1, that is increased by 20 per cent and insignificantly different from the global estimate. [ABSTRACT FROM AUTHOR]

Background: After the Great East Japan Earthquake [GEJE], approximately 70,000 Japan Ground Self Defense Force [JGSDF] personnel were deployed, risking Post-Traumatic Stress Disorder [PTSD]. The network approach to psychopathology suggests that symptoms may cause and exacerbate each other, resulting in the emergence and maintenance of disorders, including PTSD. It is therefore important to further explore the temporal interplay between symptoms. Most studies assessing the factor structure of the Impact of Event Scale-Revised [IES-R] have used cross-sectional designs. In this study, the structure of the IES-R was re-evaluated while incorporating the temporal interplay between symptoms. Methods: Using Dynamic Time Warping [DTW] the distances between PTSD symptoms on the IES-R were modelled in 1120 JGSDF personnel. Highly correlated symptoms were clustered at the group level using Distatis three-way principal component analyses of the distance matrices. The resulting clusters were compared to the original three subscales of the IES-R using a Confirmatory Factor Analysis (CFA). Results: The DTW analysis yielded four symptom clusters: Intrusion (five items), Hyperarousal (six items), Avoidance (six items), and Dissociation (five items). CFA yielded better fit estimates for this four-factor solution (RMSEA = 0.084, CFI = 0.918, TLI = 0.906), compared to the original three subscales of the IES-R (RMSEA = 0.103, CFI = 0.873, TLI = 0.858). Conclusions: DTW offers a new method of modelling the temporal relationships between symptoms. It yielded four IES-R symptom clusters, which may facilitate understanding of PTSD as a complex dynamic system. Personnel from the Japan Ground Self-Defense Force responded to the aftermath of the 2011 Great East Japan Earthquake, putting them at increased risk of developing symptoms of Post-Traumatic Stress Disorder. In recent years, psychological research has focused increasingly on methods to map the ways in which symptoms of psychopathology cause and exacerbate each other. The Dynamic Time Warping algorithm seems to be an appropriate and useful tool to analyse the interaction between post-traumatic stress symptoms over time, especially if these are not instantaneous or linear. This can improve our understanding of psychopathology and help move towards personalized medicine. [ABSTRACT FROM AUTHOR]

Slow‐earthquake signals are generally smaller than or comparable to noise levels at almost all seismological frequencies. Comprehensive detection of these events requires continuous waveforms from many stations, but such data are not always available, even in regions with high slow‐earthquake activity. We therefore need a simple and stable detection method that is also applicable to regions with sparse seismic observation networks to truly advance our understanding of slow earthquakes. Here, we utilize the proportionality between the seismic energy rate and seismic moment rate of slow earthquakes to develop a slow‐earthquake detection method using broadband waveforms from a single station. We introduce the method and estimate its performance using continuous waveform data in Japan. The new method only detects events when the tectonic tremors occur near the station, for example, 89.1% of the detections have corresponding tectonic tremor activities within 60 km, which suggests that the false‐positive rate is low. We then apply it to waveform data from the Guerrero, Oaxaca, and Jalisco regions along the Mexican subduction zone. The results for the Guerrero and Oaxaca regions are largely consistent with the geodetic and seismological results from a previous study. We also detect many events in the Jalisco region using a permanent station and provide the first seismological report of long‐term slow‐earthquake activity in this region. Some of the large‐scale slow‐earthquake activity that is detected in this study is consistent with the timings of known slow‐slip events, which implies that other unknown slow‐slip events may have occurred when we detected many events. Plain Language Summary: A relatively new type of tectonic phenomenon, slow earthquakes, has been found in many regions worldwide and investigated in detail due to their potential importance in better understanding the preparation process of large earthquakes. We can detect slow earthquakes relatively comprehensively in regions with dense observation networks, such as Japan and the west coast of the United States. However, these regions comprise a small part of the Earth's surface, and we have limited information on slow‐earthquake activity in many other regions. The purpose of this study is to expand our capability to detect and analyze slow‐earthquake activity by developing a method that can detect slow earthquakes using data from a single seismic station. The slow‐earthquake detections via our new method are consistent with previous study results in Japan and Mexico. Furthermore, we have successfully conducted the first long‐term analysis of seismological slow‐earthquake activity in the Jalisco region of Mexico. Key Points: Development of a new method to detect slow earthquakes using waveform data from a single seismic stationPresented slow‐earthquake detection is consistent with previous findings in Japan and MexicoFirst long‐term seismological analysis of slow earthquakes in the Jalisco region of Mexico [ABSTRACT FROM AUTHOR]

After the 2011 Mw 9.0 Tohoku earthquake, seismicity became extremely active throughout Japan. Despite enormous efforts to detect the large number of earthquakes, microearthquakes (M < 2 inland, M < 3 offshore) were not always cataloged and many have remained undetected, making it difficult to understand the detailed seismicity after the 2011 Tohoku earthquake. We developed an automatic hypocenter determination method combined with machine learning to detect microearthquakes. Machine learning was used for phase classification with convolutional neural networks and ensemble learning to remove false detections. We detected > 920,000 earthquakes from March 2011 to February 2012, triple the number of the conventional earthquake catalog (~ 320,000). This represents a great improvement in earthquake detection, especially in and around the Tohoku region. Detailed analysis of our merged catalog more clearly revealed features such as (1) swarm migrations, (2) small foreshock activity, and (3) increased microseismicity preceding repeating earthquakes. This microseismic catalog provides a magnifying glass for understanding detailed seismicity. [ABSTRACT FROM AUTHOR]

Seismic waves generated by an earthquake can produce dynamic perturbations in the Earth's gravity field before the direct arrival of P-waves. Observations of these so-called prompt elasto-gravity signals by ground-based gravimeters and broadband seismometers have been reported for some large events, such as the 2011 MW9.1 Tohoku earthquake. Recent studies have introduced prompt gravity strain signals (PGSSs) as a new type of observable seismic gravity perturbation that can be used to measure the spatial gradient of the perturbed gravity field. Theoretically, these types of signals can be recorded by indevelopment instruments termed gravity strainmeters, although no successful detection has been reported as yet. Herein, we propose an efficient approach for PGSSs based on a multilayered spherical Earth model. We compared the simulated waveforms with analytical solutions obtained from a homogeneous half-space model, which has been used in earlier studies. This comparison indicates that the effect of the Earth's structural stratification is significant. With the help of the new simulation approach, we also demonstrated how the PGSSs depend on the magnitude of the seismic source. We further conducted synthetic tests estimating earthquake magnitude using gravity strain signals to demonstrate the potential application of this type of signal in earthquake early warning systems. These results provide essential information for future studies on the synthesis and application of earthquake-induced gravity strain signals. [ABSTRACT FROM AUTHOR]

The magnetic effects of two similar underwater earthquakes with magnitudes of 6.0 and 7.3, which occurred on March 16, 2022, were considered in (Adushkin et al., 2023). According to the data of INTERMAGNET magnetic observatories, these earthquakes were found to be accompanied (with a delay of ~55 min) by variations in the Earth's magnetic field in the form of a train of quasi-periodic oscillations with an amplitude of ~2–8 nT and a period of ~30 min at distances of ~210 to ~3000 km from the epicenter. It was suggested in the aforementioned study that this magnetic effect is caused by a disturbance of the geodynamo as a result of the impact of seismic waves propagating deep into Earth. This interesting hypothesis requires a detailed discussion from different points of view. A more detailed analysis of the pattern of geomagnetic field disturbance at all latitudes, performed by us, leads to a conclusion that the found quasi-periodic disturbance is a mid-latitude response to auroral electrojet variations and is not related to the earthquake. According to our estimates, variations with a source at the core–mantle interface on a time scale less than one year cannot manifest themselves on the Earth's surface at all. [ABSTRACT FROM AUTHOR]

The magnetic effects of strong earthquakes are considered using the example of a unique event: two underwater earthquakes of magnitude 6.0 and 7.3 that occurred on March 16, 2022 at close times (at 14:34 and 14:36 UTC, respectively) with a distance between sources of ~11 km. With the use of data from the Mikhnevo geophysical observatory of the IDG RAS (MHV) and a number of magnetic observatories of the INTERMAGNET international network, it is shown that in the absence of global geomagnetic disturbances, earthquakes were accompanied by characteristic variations of the Earth's magnetic field recorded as a train of alternating geomagnetic field oscillations with an amplitude of ~2–8 nT and a period of ~30 min almost simultaneously at ~15:30 UTC by all magnetic observatories located at distances from 210 to ~13 000 km, as well as by variations in the periods of passage of the seismic and infrasonic signal in the MHV. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of a study showing that anomalies in the seismic regime parameters before earthquakes of various magnitudes occur in stages. The occurrence in stages means the correlation between the times of formation and development of anomalies in various seismic regime parameters. Earthquakes in regions with two general types of tectonics are selected for analysis: in the subduction zone (Kamchatka and Japan) and in the rift zone (Iceland). The selection of regions is primarily based on the availability and quality of regional seismic catalogs. GR b-value and the composite parameter known as the RTL are used as the seismic regime parameters. The detection of spatiotemporal anomalies before the selected earthquakes is based on the known "precursory patterns" of the seismic regime parameters. Comparing the durations of the detected anomalies shows that the anomalies of b-value generally occur earlier than the RTL anomalies. Possible reasons why the anomalies occur in stages are suggested. In the vicinity of the studied earthquakes, a change in the seismogenic rupture concentration parameter within the corresponding seismic cycles is also estimated. Comparing the times at which the detected seismic regime anomalies occur with the values of the seismogenic rupture concentration parameter corresponding to these times shows that the formation of seismic regime anomalies occurs at a stage when the system of seismogenic ruptures accumulated during the seismic cycle has almost reached its critical value. [ABSTRACT FROM AUTHOR]

Eboshijima, Japan is a small island in the Tsushima Strait that hosts a small colony of Japanese Murrelet Synthliboramphus wumizusume, an endangered seabird that breeds in the warm Kuroshio Current region around Japan and South Korea. We conducted a study to investigate the effects of depredation by Large-billed Crows Corvus macrorhynchos on murrelets after discovering 29 carcasses and 50 eggshells depredated by crows in four survey plots at Eboshijima in 2022. Trail cameras captured crows during daylight hours from 06h59 to 16h45. To estimate the existing population of Japanese Murrelet and predict scenarios that demonstrate the effects of corvid depredation on the murrelet population, we used a return-time (RET) capture-mark-recapture model. We evaluated the murrelet population using the best-fitting RET model and the capture histories of 187 murrelets mist-netted on Eboshijima during 2013-2022. We then simulated 1 000 iterations of a 50-year population using scenarios based on the parameters obtained from the best-fitting model. Our simulations indicate that corvid depredation could lead to the extirpation of the murrelet population, with no individuals remaining within 17 years. However, by reducing the corvid depredation effect by 50%, the probability of extinction can be lowered to less than 50% over the next 50 years. Therefore, we recommend implementing a crow translocation or removal program to protect the Eboshijima murrelet population. Additionally, further research should be conducted to identify breeding and non-breeding individuals, as well as active nesting sites. [ABSTRACT FROM AUTHOR]

We aim to better understand the overriding plate deformation during the megathrust earthquake cycle. We estimate the spatial patterns of interseismic GNSS velocities in South America, Southeast Asia and northern Japan and the associated uncertainties due to variations in network density and observation uncertainties. Interseismic velocities with respect to the overriding plate generally decrease with distance from the trench with a steep gradient up to a 'hurdle', beyond which the gradient is distinctly lower and velocities are small. The hurdle is located 500–1000 km away from the trench for the trench-perpendicular velocity component, and either at the same distance or closer for the trench-parallel component. Significant coseismic displacements were observed beyond these hurdles during the 2010 Maule, 2004 Sumatra–Andaman, and 2011 Tohoku earthquakes. We hypothesize that both the interseismic hurdle and the coseismic response result from a mechanical contrast in the overriding plate. We test our hypothesis using physically consistent, generic, 3-D finite element models of the earthquake cycle. Our models show a response similar to the interseismic and coseismic observations for a compliant near-trench overriding plate and an at least five times stiffer overriding plate beyond the contrast. The model results suggest that hurdles are more prominently expressed in observations near strongly locked megathrusts. Previous studies inferred major tectonic or geological boundaries and seismological contrasts located close to the observed hurdles in the studied overriding plates. The compliance contrast probably results from thermal, compositional and thickness contrasts and might cause the observed focusing of smaller-scale deformation like backthrusting. [ABSTRACT FROM AUTHOR]

Rachel DiNitto's book, "Fukushima Fiction: The Literary Landscape of Japan's Triple Disaster," examines the literary responses to the 2011 earthquake, tsunami, and nuclear disaster in Japan. The book analyzes various narratives that address the cultural trauma and contemporary problems resulting from the disaster. DiNitto argues that these narratives provide counter-narratives to governmental and national narratives, and also explores the connections between Fukushima fiction and atomic bomb literature as well as global nuclear fiction. While the book has some repetition and could have delved deeper into the role of nonhumans in the narratives, it is a valuable resource for researchers studying literary responses to the disaster. [Extracted from the article]

We examined whether pre-disaster Sense of Coherence (SOC) mitigated the impact of housing damage on health and well-being of older survivors after the 2011 Japan Earthquake and Tsunami. A panel survey was conducted in a city located 80 km west of the epicenter seven months before and three years after the disaster (3594 respondents). Among respondents with lighter property damage, higher SOC was inversely associated with mental distress (coefficient − 0.29, 95% CI (confidence interval) − 0.39, − 0.19, p <.01), unhappiness (coefficient − 0.33, 95% CI − 0.43, − 0.23, p <.01), low expectation of mutual help (coefficient − 0.17, 95% CI − 0.27, − 0.07, p <.01), and weak community attachment (coefficient − 0.20, 95% CI − 0.30, − 0.11, p <.01). Conversely, among those who experienced housing loss, higher SOC was no longer protectively associated with health and well-being. Loss of generalized resistance resources due to serious damage led to difficulties in stress coping. [ABSTRACT FROM AUTHOR]

Postseismic gravity changes after the 2011 Tohoku earthquake (Mw9.0) were investigated using the data from superconducting gravimeters (SGs) at Mizusawa, Japan. The data in the period from 2014 to 2021 were used in the analysis. The SG data were first corrected for instrumental drift using the results of absolute gravity measurements. Then, correction for the hydrological effect was applied based on physical modeling of soil moisture. Finally, the effect of vertical displacement of the station (free-air effect) was corrected using GNSS data. After these corrections, residual gravity indicated a long-term increase, with its rate gradually decreasing with time. This fact suggests that viscoelastic relaxation after the earthquake played an important role in producing the long-term gravity changes. Fitting a decaying exponential function of time to the residual series yielded 89.4 ± 4.4 µGal (1 µGal = 10–8 ms–2) as the total gravity change and 635 ± 17 days as the characteristic time scale. In addition to the ground-based observations, the data from satellite gravity missions GRACE/GRACE-FO were analyzed to retrieve gravity changes at Mizusawa. Similar analysis of the satellite-based data yielded 15.2 ± 1.6 µGal as the total gravity change and 3444 ± 599 days as the characteristic time scale. The difference in the estimates of the total gravity change, of a factor of about 6, from the ground-based and the satellite-based observations may be attributed to the limited spatial resolution in the latter method. The difference in the estimates of the time scale, of a factor of about 1/5, may originate from the difference in the depth where the two kinds of gravimetry are mainly sensitive. Referring to recent theoretical studies on postseismic deformations after the 2011 Tohoku earthquake, our results can be interpreted consistently by assuming the existence of a layer of viscoelastic materials with viscosity 2 × 10 18 Pa s underneath the Tohoku area of Japan. [ABSTRACT FROM AUTHOR]

This paper discusses the relationship between the vertical ground motion and ionospheric disturbances before the Kumamoto earthquake on 16 April 2016, in Kyushu, Japan, using the vertical ground motion measured by slant gauges widely distributed in Kyushu, and the NmF2 observed by ionosondes in Japan and another region. We provide evidence that vertical ground motion excites internal gravity waves (IGWs) that disturb changes in the ionospheric plasma density. From the spectral analysis results of the vertical ground motion data, the summation of various period (frequency) components analyzed from the original data of the slant gauge shows a possible correlation with the change of NmF2 before the earthquake. On the other hand, the influence of the geomagnetic disturbance on vertical ground motion seems to exist. However, we cannot confirm that vertical ground motion is influenced by the geomagnetic disturbance (Kp index) and that the earthquake is triggered by the geomagnetic disturbance. There are two conditions for the vertical ground motion to disturb variations in the ionospheric plasma density: (1) The effective vertical ground motion period should be shorter than 5 h. In addition, (2) vertical ground motion should continue to exist so that wave energy can be continuously injected into the atmosphere. A possible mechanism with which to modify the ionosphere is discussed. The results of this study can provide a basis for the future ionospheric precursors of earthquakes by using the vertical ground motion. [ABSTRACT FROM AUTHOR]

The long-period ground motions observed in recent subduction-zone earthquake events (e.g., 2011 Tohoku earthquake in Japan) have subjected high-rise buildings to large numbers of lateral cyclic deformations. Concrete-filled steel tube (CFT) columns, which are often utilized in high-rise buildings in Japan, have been studied under lateral demands with a few loading cycles. However, their seismic performance under a larger number of repeated loading cycles is a considerable concern for future seismic events. Moreover, the use of ultra-high-strength steel materials in CFT columns has recently gained popularity. However, studies on CFT columns made using ultra-high-strength steel materials are still limited. In this study, the seismic performance of CFT columns made using conventional steel or ultra-high-strength steel were investigated experimentally under repeated lateral loading cycles. Four cantilever CFT column specimens were tested with a combined constant compressive axial loading and cyclic symmetric lateral loading. Each specimen was tested with two different lateral loading protocols: the conventional protocol with two cycles at each drift amplitude level, and a second protocol with twenty cycles at each amplitude level to represent the lateral drift demand under a long-period ground motion. The effects of the number of loading cycles on the seismic performance of the CFT columns are discussed. Based on the experimental observations, design recommendations are also presented. Moreover, an approach is proposed to estimate the onset of local buckling of the CFT columns under seismic loading. [ABSTRACT FROM AUTHOR]

The stability of slopes subjected to vertical embedded strip footing loads under static and seismic conditions was investigated. The pseudostatic method was considered to represent an earthquake load. Two-dimensional lower-bound finite-element limit analysis (LB-FELA) and the strength reduction method (SRM) were employed to investigate the stability and failure mechanisms of the slopes subjected to the footing loads. It was found that the factor of safety (FOS) started to decrease rapidly after a certain load (defined as a threshold load). The critical location of the footing on the slope (where the FOS was at a minimum) was examined. In addition, a series of numerical analyses were carried out to check the effect of edge distance on slope stability. Changes in the FOS were evaluated for a particular footing edge distance for varying slope angles. The effects of variation in the shear strength parameters and the location of the water table on the slope stability under footing loads were also examined. It was found that the effect of loading intensity on the FOS was significant for gentle slopes, with this effect decreasing for steeper slopes. The influence of footing width on the FOS, for a given slope angle and loading intensity, was also insignificant. The footing near the slip surface at the top of the slope was the most critical location. The effect of the water table on the FOS diminished as the loading intensity on the footing increased. To demonstrate the practical application of this study, we also examined the slope failure that occurred during the 2011 Tohoku, Japan, earthquake. [ABSTRACT FROM AUTHOR]

The study presents seismogenic ULF (ultra-low-frequency) wave effects, as observed at our own new magnetic observatory at Asahi (geographic coordinates: 35.770° N, 140.695° E) in Chiba Prefecture. Our target earthquake (EQ) is a huge one offshore of Fukushima prefecture (37.353° N, 141.603° E) with a magnitude (M) of 7.4, which occurred at 20.59 h on November 21 UT, 2016. As a sampling frequency of 1 Hz was chosen for our induction magnetometer, we could detect both ULF wave effects: ULF radiation from the lithosphere, and the ULF depression effect, indicative of lower ionospheric perturbations. Observing the results of polarization analyses, we detected clear enhancements in ULF (frequency = 0.01–0.03 Hz) lithospheric radiation 14 days, 5 days, and 1 day before the EQ, and also observed a very obvious phenomenon of ULF (0.01–0.03 Hz) depression just 1 day prior to the EQ, which is regarded as the signature of lower ionospheric perturbations. These findings suggest that pre-EQ seismic activity must be present in the lithosphere, and also that the lower ionosphere was very much perturbed by the precursory effects of the Fukushima EQ. These new observational effects from our station have been compared with our previous investigations on different seismogenic topics for the same EQ, including the ULF observations at another magnetic observatory at Kakioka, belonging to the Japan Meteorological Agency (JMA), about 50 km north of our Asahi station, subionospheric VLF/LF propagation data (Japanese and Russian data), AGW (Atmospheric gravity wave) activity in the stratosphere, and satellite observation of particle precipitations. We have found that seismogenic anomalies of different parameters tend to happen just around the EQ day, but mainly before the EQ, and have found the chain-like tendency of the effects of the lithosphere, which seem to propagate upwards the lower ionosphere. Finally, we will try to gain a better understanding of the physical phenomena or mechanisms of the lithosphere–atmosphere–ionosphere coupling (LAIC) process during the EQ preparation phase. [ABSTRACT FROM AUTHOR]

Abstract—The response of sandy and clay subsurface soils, representing classes of non-cohesive and cohesive soils, during seismic motion of various intensities is analyzed based on the in situ observations—records by seismic vertical arrays of the Japanese strong motion network KiK-net. From a total of ~800 stations, five stations with sandy and five stations with clayey subsurface soils represented in the upper layers in their purest forms were selected for the analysis. For sandy and clayey stations, models of soil behavior during strong motion were constructed by the method of (Pavlenko and Irikura, 2003), showing vertical distributions of stresses and strains induced by strong motion in soil layers; and the behaviors were compared. Similar estimates of the amplification of seismic waves in sands and clays during weak motions and similar stress-strain relations describing the behavior of subsurface soils during moderate seismic motions are obtained. The liquefaction of sandy soils during strong motions (the 2011 Tohoku earthquake, Mw ~ 9.0) and the effects of extended seismic source (the directivity of seismic radiation) on the behavior of sandy and clayey soils and amplification of seismic waves are analyzed. Differences in the behavior of sandy and clayey soils are observed only during strong motions, namely, liquefaction occurs in sandy soils (when the groundwater level is about several meters from the surface), but never in clayey soils. [ABSTRACT FROM AUTHOR]

Concern has grown regarding how public and private sectors should make effective use of local groundwater to alleviate negative impacts of water-supply cutoff following an earthquake event, which can be regarded as an emergency groundwater governance problem. Existing literature on groundwater governance, however, is based on the tacit assumption of groundwater utilization under normal social conditions, and scant consideration has been given to the role of groundwater following occurrence of a natural disaster. This study conducted questionnaire surveys to reveal how groundwater was used in three cities (Kumamoto, Sapporo, and Sendai) in Japan struck by large earthquakes between 2010 and 2020. Results revealed substantial differences between these cities in terms of groundwater utilization following earthquake occurrence. The time between the restoration of the electricity supply and restoration of the waterworks, and the social capital accumulated by local governments, are indicated as possible reasons for such differences. Analysis also identified policy challenges for improved groundwater governance in an emergency: (1) establishment of a strategy for emergency water supply through combined use of groundwater and other water sources, (2) enhancement of methods for timely inspection of groundwater quality following occurrence of a disaster, (3) maintenance of records of the number of registered disaster emergency wells (DEWs), (4) creation of methods for publicizing locational information on DEWs with adequate regard for the privacy of well owners, and (5) recognition of the importance of making DEWs part of overall disaster preparedness. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the results determining the positions and the velocities of the 21 selected satellite laser ranging stations which performed observations from January 2008 to December 2012. This particularly interesting period of five years was selected, during which two strong earthquakes occurred near the stations. The focus was directed on the stations where the effects of the earthquakes were observed, i.e., Koganei (7308), Simosato (7838), and Changchun (7237) as a result of the tsunami in Japan on 11 February 2011, as well as Concepcion (7405IR) and San Juan (7406) as a result of the earthquake in Chile on 27 February 2010. The station positions were computed using the GSFC NASA GEODYN-II orbital software from the observations results of the satellites LAGEOS-1 and LAGEOS-2. The geocentric coordinates of the stations were determined from the normal equations of both satellites. The station velocities were computed from the positions determined for the observation epoch using the linear regression method. For each station, the following parameters were determined: mean total coordinates stability, standard deviation of determined positions and mean deviation from ITRF for topocentric components. For the best stations, the stability ranged from 4.0 mm to 6.5 mm, with the standard deviation of determined positions ranging from 0.9 mm to 1.7 mm. For two stations, a quadratic change in the station position was detected instead of a normal linear one after strong earthquakes. [ABSTRACT FROM AUTHOR]

Mineral dust affects health, climate, and ecosystems in various ways. East Asia is one of the major sources of mineral dust worldwide. This study examines the year-to-year variability of dust deposition over Japan in April from the perspective of large-scale atmospheric circulations using atmospheric and aerosol reanalysis datasets for the period from 2011 to 2017. The increased dust deposition in Japan is explained by the intensified dust transport from the Mongolian Plateau by the anomalous westerly winds associated with a deepened trough over the East Asian continent toward the northwest of the Japanese islands in the middle to lower troposphere. The enhanced dust emission over the Gobi Desert and the intensified extratropical cyclone activity are consistent with the largerthan-normal dust amount in East Asia. Comparing the dust depositions over western and northern Japan, it is suggested that the slightly different anomalous trough positions may determine whether or not a large amount of dust is carried. A further analysis using the long-term (1967 - 2022) observation data of dust in Japan supports the importance of the intensified trough over the East Asian continent. Dust flux decomposed into cyclonic and anticyclonic components showed that both vortices contribute to the eastward dust transport in East Asia. These results suggest that Japanese dust events and their variability are affected by the stationary circulation anomaly as well as the baroclinic instability waves including transient cyclones and anticyclones. [ABSTRACT FROM AUTHOR]

Approximately 70% of global tsunamis are generated within the pan Pacific Ocean region. This paper reports on detailed analysis of civilian video footage from the 2011 Tohoku earthquake, Japan. Comprehensive scientific analysis of tsunami video footage can yield valuable insights into geophysical processes and impacts. Civili22an video footage captured during the 2011 Tohoku, East Honshu, Japan tsunami was critically examined to identify key tsunami processes and estimate local inundation heights and flow velocity in Kesennuma City. Significant tsunami processes within the video were captured and orientated in ArcGIS Pro to create an OIC (Oriented Imagery Catalogue). The OIC was published to ArcGIS Online, and the oriented imagery was configured into an interactive website. Flow velocity was estimated by quantifying the distance and time taken for an object to travel between two known points in the video. Estimating inundation height was achieved by taking objects with known or calculable dimensions and measuring them against maximum local inundation height observations. The oriented imagery process produced an interactive Experience Builder app in ArcGIS Online, highlighting key tsunami processes captured within the video. The estimations of flow velocity and local inundation height quantified during video analysis indicate flow speeds ranging from 2.5–4.29 m/s and an estimated maximum local run-up height of 7.85 m in Kesennuma City. The analysis of civilian video footage provides a remarkable opportunity to investigate tsunami impact in localised areas of Japan and around the world. These data and analyses inform tsunami hazard maps, particularly in reasonably well-mapped terrains with remote access to landscape data. The results can aid in the understanding of tsunami behaviours and help inform effective mitigation strategies in tsunami-vulnerable areas. The affordable, widely accessible analysis and methodology presented here has numerous applications, and does not require highly sophisticated equipment. Tsunamis are a significant to major geohazard globally including many Pacific Island states, e.g., Papua New Guinea, Solomon Islands, and Tonga. Video footage geoscientific analysis, as here reported, can benefit tsunami and cyclone storm surge hazards in the Pacific Islands region and elsewhere. [ABSTRACT FROM AUTHOR]