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This study proposes a framework for utilizing results obtained from advanced numerical simulations and performing probabilistic tsunami hazard assessment for investigating optimal facility placement. A set of numerical simulations of the tsunami off the Pacific coast caused by the 2011 Tohoku earthquake are performed considering uncertainties in fault parameters. Both inundation depths and tsunami forces acting on buildings are numerically simulated and defined as tsunami hazard indices. Proper orthogonal decomposition is then applied to numerical results for extracting characteristic spatial modes, which can be used to construct surrogate models. Monte Carlo simulations (MCSs) were performed at a low computational cost using surrogate models. The optimal placement of facilities was probabilistically investigated with the help of genetic algorithms using the MCS results along with the concept of system failure probability. The results indicate that the proposed framework allows determining the optimal placement of facilities by applying different strategies at low computational costs while effectively reflecting the results of advanced tsunami simulations. [ABSTRACT FROM AUTHOR]

We develop a new method to analyze the total electron content (TEC) depression in the ionosphere after a tsunami occurrence. We employ Gaussian process regression to accurately estimate the TEC disturbance every 30 s using satellite observations from the global navigation satellite system (GNSS) network, even over regions without measurements. We face multiple challenges. First, the impact of the acoustic wave generated by a tsunami onto TEC levels is nonlinear and anisotropic. Second, observation points are moving. Third, the measured data are not uniformly distributed in the targeting range. Nevertheless, our method always computes the electron density depression volumes, along with estimated uncertainties, when applied to the 2011 Tohoku-Oki earthquake, even with random selections of only 5 % of the 1000 GPS Earth Observation Network System receivers considered here over Japan. Also, the statistically estimated TEC depression area mostly overlaps the range of the initial tsunami, which indicates that our method can potentially be used to estimate the initial tsunami. The method can warn of a tsunami event within 15 min of the earthquake, at high levels of confidence, even with a sparse receiver network. Hence, it is potentially applicable worldwide using the existing GNSS network. [ABSTRACT FROM AUTHOR]

This paper selects fault source models of typical earthquakes across the globe and uses a volume extending 100 km horizontally from each mainshock rupture plane and 50 km vertically as the primary area of earthquake influence for calculation and analysis. A deep neural network is constructed to model the relationship between elastic stress tensor components and aftershock state at multiple timescales, and the model is evaluated. Finally, based on the aftershock hysteresis model, the aftershock hysteresis effect of the Wenchuan earthquake in 2008 and Tohoku earthquake in 2011 is analyzed, and the aftershock hysteresis effect at different depths is compared and analyzed. The correlation between the aftershock hysteresis effect and the Omori formula is also discussed and analyzed. The constructed aftershock hysteresis model has a good fit to the data and can predict the aftershock pattern at multiple timescales after a large earthquake. Compared with the traditional aftershock spatial analysis method, the model is more effective and fully considers the distribution of actual faults, instead of treating the earthquake as a point source. The expansion rate of the aftershock pattern is negatively correlated with time, and the aftershock patterns at all timescales are roughly similar and anisotropic. [ABSTRACT FROM AUTHOR]

The 2004 Indian Ocean tsunami and the 2011 Tōhoku earthquake and tsunami caused large-scale topographic changes in coastal areas. Whereas much research has focused on coastlines that have or had large human populations, little focus has been paid to coastlines that have little or no infrastructure. The importance of examining erosional and depositional mechanisms of tsunami events lies in the rapid reorganization that coastlines must undertake immediately after an event. A thorough understanding of the pre-event conditions is paramount to understanding the natural reconstruction of the coastal environment. This study examines the location of sediment erosion and deposition during the 2004 Indian Ocean tsunami event on the relatively pristine Phra Thong Island, Thailand. Coupled with satellite imagery, we use numerical simulations and sediment transportation models to determine the locations of significant erosion and the areas where much of that sediment was redeposited during the tsunami inundation and backwash processes. Our modeling approach suggests that beaches located in two regions on Phra Thong Island were significantly eroded by the 2004 tsunami, predominantly during the backwash phase of the first and largest wave to strike the island. Although 2004 tsunami deposits are found on the island, we demonstrate that most of the sediment was deposited in the shallow coastal area, facilitating quick recovery of the beach when normal coastal processes resumed. [ABSTRACT FROM AUTHOR]

This paper selects fault source models of typical earthquakes across the globe and uses a volume extending 100 km horizontally from each mainshock rupture plane and 50 km vertically as the primary area of earthquake influence for calculation and analysis. A deep neural network is constructed to model the relationship between elastic stress tensor components and aftershock state at multiple time scales, and the model is evaluated. Finally, based on the aftershock hysteresis model, the aftershock hysteresis effect of the Wenchuan earthquake in 2008 and Tohoku earthquake in 2011 is analyzed, and the aftershock hysteresis effect at different depths is compared and analyzed. The correlation between the aftershock hysteresis effect and the Omori formula is also discussed and analyzed. The constructed aftershock hysteresis model has a good fit to the data and can predict the aftershock pattern at multiple time scales after a large earthquake. Compared with the traditional aftershock spatial analysis method, the model is more effective and fully considers the distribution of actual faults, instead of treating the earthquake as a point source. The expansion rate of the aftershock pattern is negatively correlated with time, and the aftershock patterns at all time scales are roughly similar and anisotropic. [ABSTRACT FROM AUTHOR]

The Nankai-Tonankai megathrust earthquake and tsunami pose significant risks to coastal communities in western and central Japan. Historically, this seismic region hosted many major earthquakes, and the current national tsunami hazard assessments in Japan consider megathrust events having moment magnitudes between 9.0 and 9.1. In responding to the lack of rigorous uncertainty analysis, this study presents an extensive tsunami hazard assessment for the Nankai-Tonankai Trough events, focusing upon the southwestern Pacific region of Japan. A set of 1,000 kinematic earthquake rupture models is generated via stochastic source modelling approaches, and Monte Carlo tsunami simulations are carried out by considering high-resolution grid data of 10-m and coastal defense structures. Significant advantages of the stochastic tsunami simulation methods include the enhanced capabilities to quantify the uncertainty associated with tsunami hazard assessments and to effectively visualize the results in an integrated manner. The results from the stochastic tsunami simulations can inform regional and local tsunami risk reduction actions in light of inevitable uncertainty associated with such probabilistic tsunami hazard assessments, and complement conventional deterministic tsunami scenarios and their hazard predictions, such as those developed by the Central Disaster Management Council of the Japanese Cabinet Office. [ABSTRACT FROM AUTHOR]

Bidirectional muographic measurements were conducted at the Imashirozuka burial mound, Japan. The mound was built in the beginning of the 6th century as a megalithic tomb and was later collapsed after a landslide caused by the 1596 Fushimi Earthquake, one of the largest earthquakes that have occurred in Japan over last few centuries. The measurements were conducted in order to find evidence of this past disaster recorded in this historical heritage sites. As a result, the vertical low-density regions were found at the top of the mound. These regions were interpreted as large-scale vertical cracks that caused the translational collapse process behind the rotational landslide that was already found in the prior trench-survey-based works. These results indicate that there was an intrinsic problem with the stability of the basic foundation of the Imashirozuka mound before the 1596 Fushimi Earthquake. [ABSTRACT FROM AUTHOR]

Natural fault networks are geometrically complex systems that evolve through time. The evolution of faults and their off-fault damage pattern are influenced by both dynamic earthquake ruptures and aseismic deformation in the interseismic period. To better understand each of their contributions to faulting we simulate both earthquake rupture dynamics and long-term deformation in a visco-elasto-plastic crust subjected to rate-and-state-dependent friction. The continuum mechanics-based numerical model presented here includes three new features. First, a 2.5-D approximation to incorporate effects of a viscoelastic lower crustal substrate below a finite depth. Second, we introduce a dynamically adaptive (slip-velocity-dependent) measure of fault width to ensure grid size convergence of fault angles for evolving faults. Third, fault localization is facilitated by plastic strain weakening of bulk rate-and-state friction parameters as inspired by laboratory experiments. This allows us to for the first time simulate sequences of episodic fault growth due to earthquakes and aseismic creep. Localized fault growth is simulated for four bulk rheologies ranging from persistent velocity-weakening to velocity-strengthening. Interestingly, in each of these bulk rheologies, faults predominantly localize and grow due to aseismic deformation. Yet, cyclic fault growth at more realistic growth rates is obtained for a bulk rheology that transitions from velocity-strengthening friction to velocity-weakening friction. Fault growth occurs under Riedel and conjugate angles and transitions towards wing cracks. Off-fault deformation, both distributed and localized, is typically formed during dynamic earthquake ruptures. Simulated off-fault deformation structures range from fan-shaped distributed deformation to localized Riedel splay faults. We observe that the fault-normal width of the outer damage zone saturates with increasing fault length due to the finite depth of the seismogenic zone. We also observe that dynamically and statically evolving stress fields from neighboring fault strands affect primary and secondary fault growth and thus that normal stress variations affect earthquake sequences. Finally, we find that the amount of off-fault deformation distinctly depends on the degree of optimality of a fault with respect to the prevailing but dynamically changing stress field. Typically, we simulate off-fault deformation on faults parallel to the loading direction. This produces a 6.5-fold higher off-fault energy dissipation than on an optimally oriented fault, which in turn has a 1.5-fold larger stress drop. The misalignment of the fault with respect to the static stress field thus facilitates off-fault deformation. These results imply that fault geometries bend, individual fault strands interact and that optimal orientations and off-fault deformation vary through space and time. With our work we establish the basis for simulations and analyses of complex evolving fault networks subject to both long-term and short-term dynamics. [ABSTRACT FROM AUTHOR]

Transportation infrastructure is crucial to the operation of society, particularly during post-event response and recovery. Transportation assets, such as roads and bridges, can be exposed to tsunami impacts when near the coast. Using fragility functions in an impact assessment identifies potential tsunami effects to inform decisions on potential mitigation strategies. Such functions have not been available for transportation assets exposed to tsunami hazard in the past due to limited empirical datasets. This study provides a suite of observations on the influence of tsunami inundation depth, road-use type, culverts, inundation distance, debris and coastal topography. Fragility functions are developed for roads, considering inundation depth, road-use type, and coastal topography and, for bridges, considering only inundation depth above deck base height. Fragility functions are developed for roads and bridges through combined survey and remotely sensed data for the 2011 Tōhoku earthquake and tsunami, Japan, and using post-event field survey data from the 2015 Illapel earthquake and tsunami, Chile. The fragility functions show a trend of lower tsunami vulnerability (through lower probabilities of reaching or exceeding a given damage level) for road-use categories of potentially higher construction standards. The topographic setting is also shown to affect the vulnerability of transportation assets in a tsunami, with coastal plains seeing higher initial vulnerability in some instances (e.g. for state roads with up to 5 m inundation depth) but with coastal valleys (in some locations exceeding 30 m inundation depth) seeing higher asset vulnerability overall. This study represents the first peer-reviewed example of empirical road and bridge fragility functions that consider a range of damage levels. This suite of synthesised functions is applicable to a variety of exposure and attribute types for use in global tsunami impact assessments to inform resilience and mitigation strategies. [ABSTRACT FROM AUTHOR]

The devastating Mw 7, 2010, Haiti earthquake was accompanied by local tsunamis that caused fatalities and damage to coastal infrastructure. Some were triggered by slope failures of river deltas in close vicinity of the epicenter, while others, 30 to 50 km to the north across the Bay of Gonâve, are well explained by the reverse component of coseismic ground motion that accompanied this mostly strike-slip event. However, observations of run-up heights up to 2 m along the southern coast of the island at distances up to 100 km from the epicenter, as well as tide gauge and DART buoy records at distances up to 600 km from the epicenter have not yet received an explanation. Here we demonstrate that these observations require a secondary source, most likely a submarine landslide. We identify a landslide scar 30 km from the epicenter off the southern coast of Haiti at a depth of 3500 m, where ground acceleration would have been sufficient to trigger slope failure in soft sediments. This candidate source, 2 km³ in volume, matches observation remarkably well assuming that the sediment collapse obeys a viscous flow with an initial apparent viscosity of 2 x 105 Pa s. Although that particular source cannot be proven to have been activated in 2010, our results add to a line of evidence that earthquake-triggered submarine landslides can cause significant tsunamis in areas of strike-slip tectonic regime. [ABSTRACT FROM AUTHOR]

A very high magnitude earthquake (9.1 MW) triggered a devastating Tsunami in the Indian Ocean on 26th December 2004. The epicentre was located at 3.3° N, 95.8° E with a focal depth of ~30 km. The impacts of Tsunami were felt as far away in Somalia, Tanzania and Kenya along the east coast of Africa. Considering the role of earthquake, in the present study the spatio-temporal analysis of long term (1901 to 2019) earthquake events was performed, which recorded by USGS to understand the genesis of Tsunami (2004) in the Indian Ocean. The study exhibited that the maximum frequency of earthquake was observed between the ranges of 4 MW to 6 MW on the Richter scale during 2001–2010. There was only one earthquake event > 8 MW on the Richter scale (26th December 2004 having depth 30 km) in the Indian Ocean recorded during 1901–2019. The study exhibited that the maximum earthquake was observed between 30–40 km below the surface, and primarily of moderate to low magnitudes. The proximity analysis along the major fault line indicates that the maximum earthquakes were in the buffer of 200 km from fault line in Bay of Bengal. The decadal variation of earthquake exhibits that the maximum number of earthquake events (8427 events) were triggered during the year 2001–2010, whereas during the year 2004, the total 902 earthquake events > 4 MW was recorded. The study indicates that the earthquakes > 7 MW (on Richter scale) and depth below 30 km (shallow earthquake) are primarily responsible to major Tsunami events in the Indian Ocean. The very high magnitude (> 9 MW on the Richter scale) and shallow depth (~30 km) are the major cause of 2004 Tsunami and its high level of damage. There were very low frequency (10–15 events) of earthquake occurred having magnitude > 7 and depth < 30 km. [ABSTRACT FROM AUTHOR]

A magnitude 7.5 earthquake occurred on 28 September 2018 at 10:02:43 UTC near the city of Palu on the Indonesian island of Sulawesi. It was a shallow, strike-slip earthquake with a rupture extending to a length of about 150 km and reaching the surface. Moreover, this earthquake was identified as one of very few events having a super-shear rupture speed. Clear and long-lasting infrasound signatures related to this event were observed by four infrasound arrays of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization as well as by one national infrasound station in Singapore. Although these infrasound stations SING (Singapore), I39PW (Palau), I07AU (Australia), I40PG (Papua New Guinea) and I30JP (Japan) are located at large distances of between 1800 and 4500 km from the earthquake's epicentral region, the observed infrasound signals associated with this event were intense, including both seismic and acoustic arrivals. A detailed study of the event-related infrasound observations and the potential infrasound generation mechanisms is presented, covering range-dependent infrasound transmission loss and propagation modeling and characterization of the atmospheric background conditions, as well as identification of the regions of seismoacoustic activity by applying a back-projection method from the infrasound receivers to potential source regions. This back projection of infrasonic arrivals allows one to estimate that the main infrasound source region for the Sulawesi earthquake is related to the extended rupture zone and the nearby topography. This estimation and a comparison to other super-shear as well as large regional earthquakes identify no clear connection between the earthquake's super-shear nature and the strong infrasound emission. [ABSTRACT FROM AUTHOR]

The estimate of an individual wave run-up is especially important for tsunami warning and risk assessment, as it allows for evaluating the inundation area. Here, as a model of tsunamis, we use the long single wave of positive polarity. The period of such a wave is rather long, which makes it different from the famous Korteweg–de Vries soliton. This wave nonlinearly deforms during its propagation in the ocean, which results in a steep wave front formation. Situations in which waves approach the coast with a steep front are often observed during large tsunamis, e.g. the 2004 Indian Ocean and 2011 Tohoku tsunamis. Here we study the nonlinear deformation and run-up of long single waves of positive polarity in the conjoined water basin, which consists of the constant depth section and a plane beach. The work is performed numerically and analytically in the framework of the nonlinear shallow-water theory. Analytically, wave propagation along the constant depth section and its run up on a beach are considered independently without taking into account wave interaction with the toe of the bottom slope. The propagation along the bottom of constant depth is described by the Riemann wave, while the wave run-up on a plane beach is calculated using rigorous analytical solutions of the nonlinear shallow-water theory following the Carrier–Greenspan approach. Numerically, we use the finite-volume method with the second-order UNO2 reconstruction in space and the third-order Runge–Kutta scheme with locally adaptive time steps. During wave propagation along the constant depth section, the wave becomes asymmetric with a steep wave front. It is shown that the maximum run-up height depends on the front steepness of the incoming wave approaching the toe of the bottom slope. The corresponding formula for maximum run-up height, which takes into account the wave front steepness, is proposed. [ABSTRACT FROM AUTHOR]

The Italian Tsunami Alert Centre of the Istituto Nazionale di Geofisica e Vulcanologia (Centro di Allerta Tsunami, hereinafter CAT-INGV) supported a computer-assisted telephone interview (CATI) survey to investigate tsunami risk perception in two pilot regions of southern Italy. The survey was carried out on a stratified sample of 1021 interviewees representing about 3.2 million people living in 183 coastal municipalities of the two regions, namely Calabria and Apulia. The main goal of this research is to verify whether and how people's perception of tsunami hazard compares to the results of (PTHA) – probabilistic tsunami hazard assessment (TSUMAPS-NEAM project; Basili et al., 2018). As shown by the results of this project, both investigated regions are characterised by high tsunami hazard. Nonetheless, the long return time of such events could lead people to consider the occurrence of a tsunami in the Mediterranean Sea to be very unlikely. The survey results reveal that people's risk perception is low: for almost half of the whole sample the occurrence of a tsunami in the Mediterranean Sea is considered quite unlikely, with a clear difference between Apulia and Calabria. In the latter region the risk perception is much higher than in the former, probably due to the shorter time elapsed since the last event. Also, belonging to different coastal areas For the purposes of this paper, the term "coastal area" refers to the part of the coastline defined by both seas and regions' limits, according to current geographical conventions. Tyrrhenian Calabria indicates the coastal region between the municipalities of Tortora and Scilla, Ionian Calabria spans from Reggio Calabria to Rocca Imperiale; Ionian Apulia from Ginosa to Castrignano del Capo, and Adriatic Apulia from Gagliano del Capo to Chieuti. appears to have a significant influence on the way tsunami hazard is conceived, having a stronger effect on risk characterisation: the interviewees of Tyrrhenian Calabria are indeed more likely to associate tsunami risk with volcanoes than the Ionian citizens. This is coherent considering the presence of active volcanoes and related tsunami precedents in the Tyrrhenian. Television emerged as the most relevant source of knowledge for almost 90 % of the sample, and the influence of media also results in the way tsunami risk is characterised. In particular, the survey showed that people's perception and understanding of tsunamis are affected by media accounts of large events, such as the 2004 Sumatra and the 2011 Japan tsunamis. At the same time, it is evident that the risk posed by smaller events is underrated. Furthermore, the survey's results show that the word "tsunami" occupies a different semantic space in comparison to the Italian traditional headword maremoto , with differences among sample strata. In other words, the same physical phenomenon would be understood in two different ways by younger, educated people and elders with a low education level. The results of this study, although limited to two regions, provide a first assessment of tsunami risk perception in Italy, also entailing important consequences for both risk communication practice and mitigation policies. [ABSTRACT FROM AUTHOR]

Transportation infrastructure is crucial to the operation of society, particularly during post-event response and recovery. Transportation assets, such as roads and bridges, can be exposed to tsunami impacts when near the coast. Using fragility functions in an impact assessment identifies potential tsunami effects to inform decisions on potential mitigation strategies. Such functions have not been available for transportation assets in the past due to limited empirical datasets. This study develops fragility functions for roads and bridges through combined survey and remotely sensed data for the 2011 Tohoku Earthquake and Tsunami, Japan and using post-event field survey data from the 2015 Illapel Earthquake and Tsunami, Chile. The fragility functions show a trend of lower tsunami vulnerability (through lower probabilities of reaching or exceeding a given damage level) for road use categories of potentially higher construction standards. Topographic setting is also shown to affect the vulnerability of transportation assets in a tsunami with coastal plains seeing higher initial vulnerability (e.g. up to 5 m inundation depth), but coastal valleys exceeding the maximum vulnerability of roads on coastal plains (exceeding 30 m inundation depth). This study represents the first peer-reviewed example of empirical road and bridge fragility functions that consider a range of damage levels. This suite of synthesised functions is applicable to a variety of exposure and attribute types for use in global tsunami impact assessments, to inform resilience and mitigation strategies. [ABSTRACT FROM AUTHOR]

Numerous studies have reported that ambient air pollution, which has both local and long-range sources, causes adverse impacts on the environment and human health. Previous studies have investigated the impacts of transboundary air pollution (TAP) in East Asia, albeit primarily through analyses of episodic events. In addition, it is useful to better understand the spatiotemporal variations in TAP and the resultant impact on the environment and human health. This study aimed at assessing and quantifying the air quality impacts in Japan and South Korea due to local emissions and TAP from sources in East Asia - one of the most polluted regions in the world. We applied state-of-the-science atmospheric models to simulate air quality in East Asia and then analyzed the air quality and acid deposition impacts of both local emissions and TAP sources in Japan and South Korea. Our results show that ∼ 30 % of the annual average ambient PM 2.5 concentrations in Japan and South Korea in 2010 were contributed to by local emissions within each country, while the remaining ∼ 70 % were contributed to by TAP from other countries in the region. More detailed analyses also revealed that the local contribution was higher in the metropolises of Japan (∼ 40 %–79 %) and South Korea (∼ 31 %–55 %) and that minimal seasonal variations in surface PM 2.5 occurred in Japan, whereas there was a relatively large variation in South Korea in the winter. Further, among all five studied anthropogenic emission sectors of China, the industrial sector represented the greatest contributor to annual surface PM 2.5 concentrations in Japan and South Korea, followed by the residential and power generation sectors. Results also show that TAP's impact on acid deposition (SO42- and NO3-) was larger than TAP's impact on PM 2.5 concentrations (accounting for over 80 % of the total deposition), and that seasonal variations in acid deposition were similar for both Japan and South Korea (i.e., higher in both the winter and summer). Finally, wet deposition had a greater impact on mixed forests in Japan and savannas in South Korea. Given these significant impacts of TAP in the region, it is paramount that cross-national efforts should be taken to mitigate air pollution problems across East Asia. [ABSTRACT FROM AUTHOR]

Combining pre-disaster optical and post-disaster synthetic aperture radar (SAR) data is regarded as desirable for timely damage assessment, which is essential for the prompt rescue operation. Due to the extreme differences between the two data, however, this combination has not been practically used in the previous research. In this paper, a method to assess the various types of damage caused by disasters using the desirable data combination, particularly pre-disaster very high resolution optical data and post-disaster polarimetric SAR data. The proposed method is a rule-based classification, and uses diverse components derived from the two data such as normalized difference vegetation index, polarization orientation angle, SPAN, and entropy. The proposed method was applied to the case study of the 2011 tsunami in Japan. The experimental results demonstrated the potential of the proposed method to assesses the types of tsunami-induced damage in urban and vegetated areas. The achievement in this paper is expected to facilitate efficient and fast disaster-induced complex damage assessment. [ABSTRACT FROM AUTHOR]

Recently, land cover maps created from high resolution satellite images have been used for landscape analysis, in order to understand the impact of natural disasters on biodiversity and ecosystems. Conventional land cover classification methods, however, suffer from problems with isolated pixels (salt and pepper effect). Filtering can remove the isolated pixels, but can also result in loss of accurate information. The purpose of this study is to create a land cover map for landscape analysis of large-scale disturbances caused by the Great East Japan Earthquake of 2011, utilizing a Multiple Classifier System (MCS), which allows for reduction of isolated pixels while maintaining classification accuracy. RapidEye satellite images covering the Pacific Ocean side of the Tohoku district damaged by the earthquake and subsequent tsunami were obtained for 2010, 2011, 2012 and 2016, and land cover classification was implemented using individual classifiers and the MCS method. The results showed that the MCS land cover map was able to reduce the number of isolated pixels significantly (61-71%) compared with the individual classifiers, while maintaining very high accuracy (0.976-0.986) for all four years. These results indicate that MCS land cover maps have a great potential for analyzing disturbances following infrequent largescale natural disasters such as earthquakes and tsunami, and for monitoring the process of recovery afterwards. We expect that the results of this research will be useful in managing the recovery process in the region disturbed by the Great Eastern Japan Earthquake and Tsunami of 2011, and also for developing future Ecosystem-based Disaster Risk Reduction programs for the region. [ABSTRACT FROM AUTHOR]

This publication highlights theoretical work that could explain five different empirical observations indicating a direct relationship between magnetic fields and earthquakes, which would allow the description of a causal mechanism prior to and during the occurrence of earthquakes. These theoretical calculations seek to elucidate the role of the magnetic field in different aspects of solid Earth dynamics, with an interest in the study and comprehension of the physics that could generate earthquakes accompanied by simultaneous magnetic signals within the lithosphere. The motion of charged edge dislocations (MCD) model and its correlation with the magnetic field have been used in order to include the generation of electric currents. The electric currents resulting from stress variation in the lithosphere help us to analyze the lithosphere as a critical system, before and after the occurrence of earthquakes, by using the concept of earthquake entropy. Where it is found that the nonexistence of seismic and magnetic precursors could be interpreted as a violation of the second law of thermodynamics. In addition, the seismic moment and the moment magnitude of some great earthquakes are quite accurately calculated using the coseismic magnetic field. The distance-dependent coseismic magnetic field has been theorized for some of the largest recorded earthquakes. The frequency of oscillation of the Earth's magnetic field that could be associated with earthquakes is calculated and is consistent with the ultra-low-frequency (ULF) signals that some authors propose in the so-called "LAIC effect" (lithosphere–atmosphere–ionosphere coupling). Finally, the location and dimensions of the microcracks that explain some anomalous magnetic measurements are shown. [ABSTRACT FROM AUTHOR]

This study presents the first tsunami scenario database in Marmara Sea, Turkey referring to 30 different earthquake scenarios obtained with the combinations of 32 possible fault segments. The fault mechanisms in Marmara Sea have been studied in detail within FP-7 MARSite project, which were derived from various databases and literature review. Tsunami simulations have been performed according to these defined 30 earthquake scenarios by tsunami numerical code NAMI DANCE (NAMIDANCE, 2011) which solves Nonlinear Shallow Water Equations (NLSWE) using leap-frog scheme. For each earthquake scenario, tsunami hydrodynamic parameters, mainly maximum water surface elevations, arrival time of first wave and maximum wave, and water level fluctuations were calculated at 1333 synthetic gauge points meticulously selected along the coasts of Marmara Sea. The overall simulation results indicate that maximum expected wave heights due to these earthquake scenarios are between 1 m and 2 m and even more than 2 m at some locations along Marmara coasts, such as Kadikoy, Halic and Silivri coasts in Istanbul and Bayramdere and Kursunlu districts along the coasts of Bursa province. The estimated maximum water levels at Bostanci, Pendik and Buyukada coasts in Istanbul, Cinarcik and Bandirma towns and at the entrance of Izmit Bay would reach up to 2 m. Tekirdag coasts and Buyuk Cekmece and Bakirkoy coasts in Istanbul and Yalova coasts would experience maximum tsunami wave amplitudes around 1.5 m. The waves reach up to 1 m at Izmit and Gemlik Bays, Erdek Peninsula and Marmara Island. The overwiew of the results reveal that higher historical tsunami wave heights observed in Marmara Sea cannot be explained by only earthquake-generated tsunamis. Therefore, there is strong agreement on considering submarine landslides as the primary tsunami hazard component in the Marmara Sea as experienced during history and expected in the future. [ABSTRACT FROM AUTHOR]

A magnitude 7.5 earthquake occurred on September 28th 2018 at 10:02:43 UTC near the city of Palu on the Indonesian island of Sulawesi. It was a shallow, strike-slip earthquake with fractures up to the surface and a rupture length of about 150 km. Moreover, this earthquake was identified as one of very few events having a super shear rupture speed. Clear and long-lasting infrasound signatures related to this event were observed by four infrasound arrays of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty Organization as well as one national infrasound station in Singapore. Although these infrasound stations SING (Singapore), I39PW (Palau), I07AU (Australia), I40PG (Papua New Guinea) and I30JP (Japan) are located in large distances between 1800 km and 4500 km from the earthquake's epicentral region, the observed infrasound signals associated to this event were intense, including both seismic and acoustic arrivals. The seismic-to-acoustic coupling at nearby terrain features is supposed to generate distinct infrasonic signatures clearly recordable at remote infrasound arrays. A detailed study of the event-related observations and the potential infrasound generation mechanisms is presented covering range- and time-dependent infrasound attenuation and propagation modeling, characterization of the atmospheric background conditions as well as identification of the regions of seismoacoustic activity by applying a backtracking method from the infrasound receivers to potential source regions. The back-projection of infrasonic arrivals allows to estimate that the main infrasound source region for the Sulawesi earthquake is related to the extended rupture zone and the nearby topography. This estimation and the comparison to other super shear as well as large regional earthquakes identifies no clear connection between the earthquake's super shear nature and the strong infrasound emission. [ABSTRACT FROM AUTHOR]

The analysis of earthquake time series in a new time domain termed natural time enables the uncovering of hidden properties in time series of complex systems and has been recently employed as the basis of a method to estimate seismic risk. Natural time also enables the determination of the order parameter of seismicity, which is a quantity by means of which one can identify when the system approaches the critical point (the mainshock occurrence is considered the new phase). Applying this analysis, as an example, to the Japanese seismic data from 1 January 1984 until the super-giant M 9 Tōhoku earthquake on 11 March 2011, we find that almost 3 months before its occurrence the entropy change of seismicity under time reversal is minimized on 22 December 2010, which signals an impending major earthquake. On this date the order parameter fluctuations of seismicity exhibit an abrupt increase. This increase is accompanied by various phenomena; e.g., from this date the horizontal GPS azimuths start to become gradually oriented toward the southern direction, while they had random orientation during the preceding period. Two weeks later, a minimum of the order parameter fluctuations of seismicity appears accompanied by anomalous Earth magnetic field variations and by full alignment of the orientations of GPS azimuths southwards leading to the most intense crust uplift. These phenomena are discussed and found to be in accordance with a physical model which seems to explain on a unified basis anomalous precursory changes observed either in ground-based measurements or in satellite data. [ABSTRACT FROM AUTHOR]

International cooperation in seismology emerged rapidly at the beginning of the 20th century following the successful recording of earthquakes at great distances. The International Seismological Association (ISA) founded in 1904 was dissolved in 1922 and evolved into the Seismology Section of the International Union of Geodesy and Geophysics (IUGG), ultimately becoming the International Association of Seismology and Physics of the Earth's Interior (IASPEI) to recognize the important role of the structure and physical properties of the Earth. Through the last hundred years, the commissions and working groups of the association have played a major role in setting international standards in such areas as the naming of seismic phases, data exchanges, travel-time tables, magnitude scales, and reference Earth models. The activities of IASPEI continue to have a focus on the societal impacts of earthquakes and tsunamis, with four regional commissions playing a major role in promoting high standards of seismological education, outreach, and international scientific cooperation. [ABSTRACT FROM AUTHOR]

We examined the impact of the earthquake and tsunami following the 2011 off the Pacific coast of Tohoku earthquake on the deep-sea benthic ecosystems based on radionuclide and benthic foraminiferal analysis of core sediments, collected from 3200 and 3600 m water depths 5 and 17 months after the earthquake. Radionuclide analysis of the excess 210Pb, 134Cs, and 137Cs indicated that some of the analyzed sediment core recorded deposits before the earthquake, event deposits just after the earthquake, and deposits after the Fukushima Daiichi Nuclear Power Plant accident, which caused the release of a large amount of radioactive material 4 days after the earthquake. Uvigerina senticosa, Chilostomella oolina, and Elphidium batialis were the dominant species in the study area prior to the earthquake. In core 4W-2012, the original or pre-earthquake assemblage layer was covered by 5-cm-thick event deposits following the earthquake that contained a high diversity allochthonous foraminiferal assemblage. Following the episodic deposition, foraminiferal density drastically decreased and many species disappeared, resulting in a decrease in species diversity. Above 10 cm depth in the sediment, living specimens of opportunistic and competitive species gradually increased toward the sediment surface and became dominant in the top 1 cm of the core. Thus, the episodic deposition resulting from the earthquake caused a drastic decrease in the original benthic foraminifera and colonization of opportunistic species with a low diversity within 17 months. Although there were differences in vertical change in the radionuclides and benthic foraminifera between sites, faunal change may have already occurred 5 months after the earthquake. [ABSTRACT FROM AUTHOR]

Run-up processes of the 2011 Tohoku tsunami into the city of Kamaishi, Japan, were simulated numerically using 2-D shallow water equations with a new treatment of building footprints. The model imposes an internal hydraulic condition of permeable and impermeable walls at the building footprint outline on unstructured triangular meshes. Digital data of the building footprint approximated by polygons were overlaid on a 1.0m resolution terrain model. The hydraulic boundary conditions were ascertained using conventional tsunami propagation calculation from the seismic center to nearshore areas. Run-up flow calculations were conducted under the same hydraulic conditions for several cases having different building permeabilities. Comparison of computation results with field data suggests that the case with a small amount of wall permeability gives better agreement than the case with impermeable condition. Spatial mapping of an indicator for run-up flow intensity (IF D. hU²/max, where h and U respectively denote the inundation depth and flow velocity during the flood, shows fairly good correlation with the distribution of houses destroyed by flooding. As a possible mitigation measure, the influence of the buildings on the flow was assessed using a numerical experiment for solid buildings arrayed alternately in two lines along the coast. Results show that the buildings can prevent seawater from flowing straight to the city center while maintaining access to the sea. [ABSTRACT FROM AUTHOR]

Recently, high-resolution commercial SAR satellites with several meters of resolutions are widely utilized for various applications and disaster monitoring is one of the commonly applied areas. The information about the flooding situation and ground displacement was rapidly announced to the public after the Great East Japan Earthquake 2011. One of the studies reported the displacement in Tohoku region by the pixel matching methodology using both pre- and post- event TerraSAR-X data, and the validated accuracy was about 30 cm at the GEONET reference points. In order to discuss the spatial distribution of the displacement, we need to evaluate the relative accuracy of the displacement in addition to the absolute accuracy. In the previous studies, our study team evaluated the absolute 2D geo-location accuracy of the TerraSAR-X ortho-rectified EEC product for both flat and mountain areas. Therefore, the purpose of the current study was to evaluate the spatial and temporal relative geo-location accuracies of the product by considering the displacement of the fixed point as the relative geo-location accuracy. Firstly, by utilizing TerraSAR-X StripMap dataset, the pixel matching method for estimating the displacement with sub-pixel level was developed. Secondly, the validity of the method was confirmed by comparing with GEONET data. We confirmed that the accuracy of the displacement for X and Y direction was in agreement with the previous studies. Subsequently, the methodology was applied to 20 pairs of data set for areas of Tokyo Ota-ku and Kawasaki-shi, and the displacement of each pair was evaluated. It was revealed that the time series displacement rate had the seasonal trend and seemed to be related to atmospheric delay. [ABSTRACT FROM AUTHOR]

The recently adopted 'Sendai Framework for Action on Disaster Risk Reduction 2015-2030' sets the goals to reduce loss of life, livelihood and critical infrastructure through enhanced national planning and international cooperation. The new Framework is expected to enhance global, regional and national efforts for building resilience to disasters, across the entire disaster management cycle (prevention, preparedness, response and early recovery). Improved monitoring and accountability frameworks, relying on harmonized disaster loss data will be required for meeting the targets and for capturing the levels of progress across different scales of governance. To overcome the problems of heterogeneous disaster data and terminologies, guidelines for reporting disaster damage and losses in a structured manner will be necessary to help national and regional bodies compile this information. In the European Union, the Member States and the European Commission worked together on the establishment of guidelines for recording and sharing disaster damage and loss data as a first step towards the development of operational indicators to translate the Sendai Framework into action. This paper describes the progress to date in setting a common framework for recording disaster damage and loss data in the European Union and identifies the challenges ahead. [ABSTRACT FROM AUTHOR]

The Great East Japan Earthquake on March 11, 2011 is said to be a once-in-1000-year catastrophic quake. The Tsunami triggered by the earthquake destroyed broad coastal areas in northeast Japan. As recovery from the earthquake proceeds, the demand for new road construction, housing hill development, and residential construction is rapidly increasing. Culture plays a critical role in the district's recovery. For that reason, before development, cultural properties in the corresponding districts must be urgently investigated. This is a must, although balancing cultural recovery with rapid economic recovery is no easy task. With this in mind, we have developed a new system focusing on speedy archaeological investigation and adequate documentation. The authors reexamined the existing investigation process to categorize tasks into two types: those that must be done only at archaeological sites (site A) and ones available at other places (site B). We then formulated a scheme where the tasks on both sites are performed simultaneously in parallel over the network. Experiments are ongoing. This presentation reports the process and issues of our research and development. [ABSTRACT FROM AUTHOR]

The Great East Japan Earthquake (magnitude 9.0; occurred on 11th March 2011) and subsequent huge tsunami caused widespread damage along the Pacific Ocean coast of eastern Honshu, Japan. This research utilizes multi-resolution remote sensing images to clarify the impact on landscapes caused by this disaster, and also to monitor the subsequent survival and recovery process in the Sendai Bay region. The coastal landscape in the target area features a narrow strip of coastal sand barrier, historically stabilized by planted pine groves; backed by a low-lying plain that has traditionally been diked and converted to irrigated rice paddies. Farmsteads on the flat alluvial plain are surrounded by groves called "Igune", consisting primarily of conifers. MODIS data (250 m resolution) were employed to map the overall extent of inundation and damage on the regional landscape scale. The major damage caused by the tsunami, destruction of coastal pine forests and inundation or rice paddies on the plain, was identified at this level. Progressively finer scale analysis were then implemented using SPOT/HRG-2 (10 m resolution) data; GeoEye-1 fine resolution data (0.5 m) and very fine resolution aerial photographs (10 cm) and LiDAR. These results demonstrated the minute details of the damage and recovery process. Some patches of pine forest, for example, were seen to have survived, and some coastal plant communities were already recovering only a year after the disaster. Continuous monitoring using field work and remote sensing is required for balanced regional strategies that provide for economic and social recovery and as well as restoration of vegetation, biodiversity and vital ecosystem services. [ABSTRACT FROM AUTHOR]

The Tohoku-Oki earthquake on 11 March 2011 caused significant widespread crustal movements. In a previous study, we proposed a method for capturing twodimensional (2-D) surface displacements from a pair of preand post-event TerraSAR-X (TSX) intensity images. However, it is impossible to detect three-dimensional (3-D) displacements from one pair of TSX images. In this study, three pairs of pre- and post-event TSX images taken on different paths were used to estimate 3-D crustal movements. The relationship between the actual 3-D displacements and the converted 2-D movements in the synthetic-aperture radar (SAR) images was derived based on the observation model of a SAR sensor. The 3-D movements were then calculated from three sets of detected 2-D movements that occurred within a short time period. Compared with GPS observations, the proposed method was found to be capable of detecting the 3-D crustal movements with sub-pixel accuracy. [ABSTRACT FROM AUTHOR]

The modelling or prediction of complex geospatial phenomena (like formation of geo-hazards) is one of the most important tasks for geoscientists. But in practice it faces various difficulties, caused mainly by the complexity of relationships between the phenomena itself and the controlling parameters, as well by limitations of our knowledge about the nature of physical/ mathematical relationships and by restrictions regarding accuracy and availability of data. In this situation methods of artificial intelligence, like artificial neural networks (ANN) offer a meaningful alternative modelling approach compared to the exact mathematical modelling. In the past, the application of ANN technologies in geosciences was primarily limited due to difficulties to integrate it into geo-data processing algorithms. In consideration of this background, the software advangeo® was developed to provide a normal GIS user with a powerful tool to use ANNs for prediction mapping and data preparation within his standard ESRI ArcGIS environment. In many case studies, such as land use planning, geo-hazards analysis and prevention, mineral potential mapping, agriculture & forestry advangeo® has shown its capabilities and strengths. The approach is able to add considerable value to existing data. [ABSTRACT FROM AUTHOR]

Due to the 11 March 2011 Tohoku earthquake, massive radioactive materials were released from the Fukushima Daiichi Nuclear Power Plant (Fukushima NPP). It is crucial to predict the regional distribution and magnitude of the effects on wildlife by radioactive materials. However, during the post-accident early stage in 2011, limited information on large-scale pollution and prediction maps was open to public. Hence, this paper aimed to provide (1) the pollution map covering areas within 300 km from the Fukushima NPP where the radiation intensity exceeded 0.5 µSv/h, (2) pollution maps which predicted air dose for the next 30 years after the accident, and (3) maps of areas where wildlife might be affected by radioactive isotopes by the Fukushima nuclear accident. First, the relative contributions of 131I, 134Cs, and 137Cs were estimated from time series observation data. Second, a 30-year prediction of the pollution was calculated based on the isotope half-lives. Third, the chronic radiation effects on vertebrates were estimated using the threshold dose rate proposed by Sazykina et al. (2009). We examined the chronic radiation effects on morbidity, reproduction, and longevity. The results indicated that radioactive materials could have affected vertebrate morbidity within a 350 km2 area in early April 2011; the threshold level was the median result of Sazykina et al. (2009) with bootstrapping. Based on the prediction, a 15.5 km² region will remain affected after 30 years. These areas should be monitored to confirm the effects of radioactivity on wildlife. [ABSTRACT FROM AUTHOR]

In this study, we present first results of RAPIDMAP, a project funded by European Union in a framework aiming to foster the cooperation of European countries with Japan in R&D. The main objective of RAPIDMAP is to construct a Decision Support System (DSS) based on remote sensing data and WebGIS technologies, where users can easily access real-time information assisting with disaster analysis. In this paper, we present a case study of the Tohoku Tsunami Disaster 2011. We address two approaches namely change detection based on SAR data and co-registration of optical and SAR satellite images. With respect to SAR data, our efforts are subdivided into three parts: (1) initial coarse change detection for entire area, (2) flood area detection, and (3) linearfeature change detection. The investigations are based on pre- and post-event TerraSAR-X images. In (1), two pre- and post-event TerraSAR-X images are accurately co-registered and radiometrically calibrated. Data are fused in a false-color image that provides a quick and rough overview of potential changes, which is useful for initial decision making and identifying areas worthwhile to be analysed further in more depth. However, a bunch of inevitable false alarms appear within the scene caused by speckle, temporal decorrelation, co-registration inaccuracy and so on. In (2), the post-event TerraSAR-X data are used to extract the flood area by using thresholding and morphological approaches. The validated result indicates that using SAR data combining with suitable morphological approaches is a quick and effective way to detect flood area. Except for usage of SAR data, the false-color image composed of optical images are also used to detect flood area for further exploration in this part. In (3), Curvelet filtering is applied in the difference image of pre- and post-event TerraSAR-X images not only to suppress false alarms of irregular-features, but also to enhance the change signals of linear-features (e.g. buildings) in settlements. Afterwards, thresholding is exploited to extract the linear-feature changes. In rapid mapping of disasters various sensors are often employed, including optical and SAR, since they provide complementary information. Such data needs to be analyzed in an integrated fashion and the results from each dataset should be integrated in a GIS with a common coordinate reference system. Thus, if no orthoimages can be generated, the images should be co-registered employing matching of common features. We present results of co-registration between optical (FORMOSAT-2) and TerraSAR-X images based on different matching methods, and also techniques for detecting and eliminating matching errors. [ABSTRACT FROM AUTHOR]

Eruptive rates in volcanic arcs increase significantly after subduction mega-thrust earthquakes. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress σh promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilisation by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five recent megathrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all but one the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. We suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes may be followed closely by indications of rising magma to shallower depths, e.g. surface inflation and seismic swarms. [ABSTRACT FROM AUTHOR]

The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1). Fission products were emitted, falling over a broad range in the Northern Hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radio-cesium in zooplankton and in seawater in the western North Pacific Ocean (500-2100 km from the FNPP1) 10 months after the accident. 134Cs and 137Cs were detected in zooplankton and seawater from all the stations. Because of its short half-life, the 134Cs detected in our samples could only be derived from the FNPP1 accident. The highest 137Cs activity in zooplankton was the same order of magnitude as it was one month after the accident, and average activity was one or two orders of magnitude higher than 137Cs activities observed before the accident around Japan. Horizontally, the radiocesium activity concentrations in zooplankton were high at around 25° N while those in surface seawater were high at around the transition area between the Kuroshio and the Oyashio currents (36-40° N). We observed subsurface radio-cesium maxima in density range of the North Pacific Subtropical Mode Water and the occurrence of many diel vertical migratory zooplankton. These suggested that the high activity concentrations in the subtropical zooplankton at around 25° N were connected to the subsurface radiocesium and active vertical migration of zooplankton. However, the high activity concentrations of radiocesium in subsurface seawater did not necessarily correlate with the higher radiocesium activity in zooplankton. Activity concentrations of radiocesium in zooplankton might be influenced not only by the environmental radiocesium activity concentrations but also by other factors, which are still unknown. [ABSTRACT FROM AUTHOR]

A series of accidents at the Fukushima Dai-ichi Nuclear Power Plant following the Great East Japan Earthquake and tsunami of 11 March 2011 resulted in the release of radioactive materials to the ocean by two major pathways: direct release from the accident site and atmospheric deposition. A 1yr, regional-scale simulation of 137Cs activity in the ocean offshore of Fukushima was carried out, the sources of radioactivity being direct release, atmospheric deposition, and the inflow of 137Cs deposited into the ocean by atmospheric deposition outside the domain of the model. Direct releases of 137Cs were estimated for 1 yr after the accident by comparing simulated results and measured activities adjacent to the accident site. The contributions of each source were estimated by analysis of 131I/137Cs and 134Cs/137Cs activity ratios and comparisons between simulated results and measured activities of 137Cs. The estimated total amounts of directly released 131I, 134Cs, and 137Cs were 11.1 ± 2.2PBq, 3.5±0.7PBq, and 3.6 ±0.7 PBq, respectively. Simulated 137Cs activities attributable to direct release were in good agreement with measured 137Cs activities not only adjacent to the accident site, but also in a wide area in the model domain, therefore this implies that the estimated direct release rate was reasonable. Employment of improved nudging data by JCOPE2 improved both the offshore transport result and the reproducibility of 137Cs activities 30 km offshore. On the other hand, simulated 137Cs activities attributable to atmospheric deposition were low compared to measured activities. The rate of atmospheric deposition into the ocean was underestimated because of a lack of measurements of deposition into the ocean when atmospheric deposition rates were being estimated. Simulated 137Cs activities attributable to the inflow of 137Cs deposited into the ocean outside the domain of the model were in good agreement with measured activities in the open ocean within the model domain after June 2012. The consideration of inflow is important to simulate the 137Cs activity in this model region in the later period of the simulation. The contribution of inflow increased with time and was dominant (more than 99 %) by the end of February 2012. The activity of directly released 137Cs, however, decreased exponentially with time and was detectable only in the coastal zone by the end of February 2012. [ABSTRACT FROM AUTHOR]

The magnitude of the 9.0 Tohoku earthquake and the ensuing tsunami on 11 March 2011, inflicted heavy damage on the Fukushima Dai-ichi nuclear power plant (FNPP1). Fission products were emitted, falling over a broad range in the northern hemisphere, and water contaminated with radionuclides leaked into the ocean. In this study, we described the horizontal distribution of the Fukushima-derived radiocesium in zooplankton and in seawater in the western North Pacific Ocean (500-2100 km from the FNPP1) 10 months after the accident. 134Cs and 137Cs were detected in zooplankton and seawater from all the stations. Because of its short half-lives, 134Cs detected in our samples could only be derived from the FNPP1 accident. The highest 137Cs activity in zooplankton was same order of magnitude as that one month after the accident, and average activity was one or two orders of magnitude higher than 137Cs activities observed before the accident around Japan. Horizontally, the radiocesium activity concentrations in zooplankton were high at around 25°N while those in surface seawater were high at around the transition area between the Kuroshio and the Oyashio Currents (36-40°N). We observed subsurface radiocesium maxima in density range of the North Pacific Subtropical Mode Water and occurrence of many diel vertical migratory zooplanktons. These suggested that the high activity concentrations in the subtropical zooplankton at around 25°N were connected to the subsurface radiocesium and active vertical migration of zooplankton. However, the high activity concentrations of radiocesium in subsurface seawater did not necessarily follow the higher radiocesium activity in zooplankton. Biological characteristics of zooplankton community possibly influenced how large was contamination of radiocesium in the community but it is still unknown what kind of biological factors were important. [ABSTRACT FROM AUTHOR]

The 2011 Tohoku earthquake caused radionuclide 137Cs be directly released into the ocean from the Fukushima Dai-ichi nuclear power plants. A high-resolution global-coastal nesting ocean model was established to simulate the initial spread of 137Cs as conservative tracer over the shelf of Japan after the accident. The major advantage in the current model system is to use unstructured grids to resolve the power plant and the coastal geometry with a grid resolution much higher than that used in previous modeling experiments. Therefore, it gives us an opportunity to examine the necessity whether the detailed structure of the Power plant should be considered for numerical experiment of 137Cs dispersion or not. This could provide us an alternative insight into the physical processes that lead to its spread of 137Cs over the shelf of Japan. Our results suggested that to resolve the dispersion process from the source point to the south and north discharging canal is critical for an accurate prediction of the spread of 137Cs to the 30 km sites off the coast. Moreover, a 2 km grid resolution along Japan coast is probably not high enough to resolve the plume correctly. Finally, the model- data comparison suggested that the physical process associated with the transfer of dissolved 137Cs into the sediment phase could potentially be important and should be considered in the future tracer modeling. [ABSTRACT FROM AUTHOR]

Manifestations of disturbances in the lower ionosphere caused by a complex series of earthquakes (the strong earthquakes with M = 7.3 and M = 9 -- known as M9 Tohoku EQ -- and the subsequent aftershocks) that occurred near the Japanese island of Honshu have been considered with the use of monitoring measurements of the amplitude of lightning electromagnetic signals (atmospherics) received at Yakutsk. Some data of one-point lightning location systems have been compared with the data of the WWLLN network. The analysis of hourly values variation of the atmospheric amplitude passing over the earthquake epicenters shows that during the initial period (the strong earthquakes on 9 March and 11 March) a typical pattern of variations was observed. It was manifested in the increased amplitude after both earthquakes. There were also possible precursors in the form of the increase in amplitude 12--14 days before the events. Though the focuses of these earthquakes were very close to each other, the registration of both precursors may indicate that both of the lithospheric processes developed to a certain extent independently. During all the days of the atmospheric amplitude enhancement the quasi-periodic variation trains were recorded. Together with the delay of earthquake effects relative to the time of the events, they may testify in favor of transferring the energy of lithospheric processes into the lower ionosphere by means of atmospheric gravity waves. [ABSTRACT FROM AUTHOR]

Real-time detection of a tsunami on instrumental sea-level records is quite an important task for a Tsunami Warning System (TWS), and in case of alert conditions for an ongoing tsunami it is often performed by visual inspection in operational warning centres. In this paper we stress the importance of automatic detection algorithms and apply the TEDA (Tsunami Early Detection Algorithm) to identify tsunami arrivals of the 2011 Tohoku tsunami in a real-time virtual exercise. TEDA is designed to work at station level, that is on sea-level data of a single station, and was calibrated on data from the Adak island, Alaska, USA, tide-gauge station. Using the parameters' configuration devised for the Adak station, the TEDA has been applied to 123 coastal sealevel records from the coasts of the Pacific Ocean, which enabled us to evaluate the efficiency and sensitivity of the algorithm on a wide range of background conditions and of signal-to-noise ratios. The result is that TEDA is able to detect quickly the majority of the tsunami signals and therefore proves to have the potential for being a valid tool in the operational TWS practice. [ABSTRACT FROM AUTHOR]

On 11 March 2011 at 14:46:23 LT, the 4th largest earthquake ever recorded with a magnitude of 9.0 occurred near the northeast coast of Honshu in Japan (38.322° N, 142.369° E, Focal depth 29.0 km). In order to acknowledge the capabilities of Total Electron Content (TEC) ionospheric precursor, in this study four methods including mean, median, wavelet transform, and Kalman filter have been applied to detect anomalous TEC variations concerning the Tohoku earthquake. The duration of the TEC time series dataset is 49 days at a time resolution of 2 h. All four methods detected a considerable number of anomalous occurrences during 1 to 10 days prior to the earthquake in a period of high geomagnetic activities. In this study, geomagnetic indices (i.e. Dst, Kp, Ap and F10.7) were used to distinguish pre-earthquake anomalies from the other anomalies related to the geomagnetic and solar activities. A good agreement in results was found between the different applied anomaly detection methods on TEC data. [ABSTRACT FROM AUTHOR]

In the aftermath of an earthquake and tsunami on 11 March 2011 radioactive 137Cs was discharged from a damaged nuclear power plant to the sea off Fukushima Daiichi, Japan. Here we explore its dilution and fate with a stateof- the-art global ocean general circulation model, which is eddy-resolving in the region of interest. We find apparent consistency between our simulated circulation, estimates of 137Cs discharged ranging from 0.94pBq (Japanese Government, 2011) to 3.5±0.7pBq (Tsumune et al., 2012), and measurements by Japanese authorities and the power plant operator. In contrast, our simulations are apparently inconsistent with the high 27±15pBq discharge estimate of Bailly du Bois et al. (2012). Expressed in terms of a diffusivity we diagnose, from our simulations, an initial dilution on the shelf of 60 to 100m²; s-1 . The cross-shelf diffusivity is at 500±300m²s-1 significantly higher and variable in time as indicated by its uncertainty. Expressed as an effective residence time of surface water on the shelf, the latter estimate transfers to 43±16 days. As regards the fate of 137Cs, our simulations suggest that activities up to 4mBql-1 prevail in the Kuroshio-Oyashio Interfrontal Zone one year after the accident. This allows for low but detectable 0.1 to 0.3mBql-1 entering the North Pacific Intermediate Water before the 137Cs signal is flushed away. The latter estimates concern the direct release to the sea only. [ABSTRACT FROM AUTHOR]

The 11 March 2011 Tohoku tsunami is simulated using the quadtree-adaptive Saint-Venant solver implemented within the Gerris Flow Solver. The spatial resolution is adapted dynamically from 250m in flooded areas up to 250 km for the areas at rest. Wave fronts are tracked at a resolution of 1.8 km in deep water. The simulation domain extends over 73° of both latitude and longitude and covers a significant part of the north-west Pacific. The initial wave elevation is obtained from a source model derived using seismic data only. Accurate long-distance wave prediction is demonstrated through comparison with DART buoys timeseries and GLOSS tide gauges records. The model also accurately predicts fine-scale flooding compared to both satellite and survey data. Adaptive mesh refinement leads to ordersof- magnitude gains in computational efficiency compared to non-adaptive methods. The study confirms that consistent source models for tsunami initiation can be obtained from seismic data only. However, while the observed extreme wave elevations are reproduced by the model, they are located further south than in the surveyed data. Comparisons with inshore wave buoys data indicate that this may be due to an incomplete understanding of the local wave generation mechanisms. [ABSTRACT FROM AUTHOR]

On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2-18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137Cs, the inversion results give a total emission of 36.6 (20.1-53.1) PBq, or about 43% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude at the time when spraying of water on the spentfuel pool of unit 4 started. This indicates that emissions may not have originated only from the damaged reactor cores, but also from the spent-fuel pool of unit 4. This would also con- firm that the spraying was an effective countermeasure. We explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. Radioactive clouds reached North America on 15 March and Europe on 22 March. By middle of April, 133Xe was fairly uniformly distributed in the middle latitudes of the entire Northern Hemisphere and was for the first time also measured in the Southern Hemisphere (Darwin station, Australia). In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement. Altogether, we estimate that 6.4 PBq of 137Cs, or 18% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 PBq, or 1.9% of the total fallout were deposited on land areas other than Japan. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the high resolution tomographic images of the crust and upper mantle in and around the area of the 2011 Iwaki earthquake and the Fukushima nuclear power plant in Japan. It reveals that the Iwaki earthquake was triggered by the ascending fluids from the Pacific slab dehydration and the stress variation induced by the Tohoku-oki mainshock. It suggests strengthening the security of the nuclear power plant site to withstand potential large earthquakes.

In the aftermath of an earthquake and tsunami on 11 March 2011 considerable amounts of radioactive materials were accidentally released into the sea off Fukushima-Daiichi, Japan. This study uses a three-dimensional eddy-resolving oceanic general circulation model to explore potential pathways of a tracer, similar to 137Cs, from the coast to the open ocean. Results indicate that enhanced concentrations meet a receding spring bloom offshore and that the area of enhanced concentrations offshore is strongly determined by surface mixed layer dynamics. However, huge uncertainties remain. Among them are the realism of the simulated cross-shelf transport and apparently inconsistent estimates of the particle reactivity of 137Cs which are discussed in a brief literature review. We argue that a comprehensive set of 137Cs measurements, including sites offshore, could be a unique opportunity to both evaluate and advance the evaluation of oceanic general circulation models. [ABSTRACT FROM AUTHOR]