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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]

Tsunami inundation maps are crucial for understanding the impact of tsunamis and planning mitigation measures. Our research focuses on creating a database of stochastic tsunami scenarios along the Chilean subduction zone and probabilistic inundation maps for 11 coastal cities. We divided the Chile-Perú subduction zone into four seismic segments based on historical seismicity. Stochastic rupture scenarios, ranging from 8.0 to 9.6 magnitudes, were generated using the Karhunen-Loeve expansion. The Stochastic Reduced Order Model (SROM) helped select representative tsunami scenarios for each segment and magnitude bin. We then used the NEOWAVE model to simulate these scenarios to an inundation level, creating probabilistic tsunami maps for various return periods. Our findings reveal that local geography significantly influences tsunami inundation, with some areas facing high inundation risks while others experience minimal impacts. As a result, a uniform planning and design criterion across the entire country is not advisable; site-specific studies are necessary. These probabilistic scenarios can provide tailored solutions for different Chilean coastal cities, enhancing their resilience. Additionally, this research marks the first comprehensive probabilistic tsunami hazard analysis for the Chilean coast, considering multiple seismic sources, marking a crucial step toward full tsunami risk assessment for coastal communities. [ABSTRACT FROM AUTHOR]

The Makran Subduction Zone (MSZ) in the northwestern Indian Ocean can generate large tsunamigenic thrust earthquakes affecting the coastal regions of Pakistan, Iran, Oman, and western India. In this paper, a probabilistic tsunami hazard assessment is conducted for the MSZ using stochastic tsunami simulations of moment magnitude (Mw) of 7.7–9.1 earthquake scenarios. This study investigates uncertainties associated with earthquake occurrence rate, single-segment (eastern and western MSZ) or two-segment (full MSZ) rupture scenarios, source geometry, and slip heterogeneity. The total number of simulated source models is 15,000. This study presents two major categories of results: stochastic source models and ranges of 475, 975, and 2475-year tsunami heights. For instance, tsunami heights generated by Mw 8.5‒8.7 stochastic sources of western MSZ vary between 1 m and 10 m with a mean of ~ 4.5 m in the affected areas. The tsunami heights are sensitive to the source models' characteristics, such as location of the large slip areas, bathymetry of the nearshore area, and the location of bays. Considering different occurrence rates results in significant variability in the estimated 475, 975, and 2475-year tsunami heights. For example, 2475-year tsunami height in Chabahar is in the range of 3‒7.4 m at 10 m water depth. [ABSTRACT FROM AUTHOR]

In ancient records, discrimination of specific triggering events from sediment gravity flow deposits is very difficult, due to multiple interactions between triggering events and similar sedimentary characteristics. For this study, we introduce the Hakcheon-Chogok Megaturbidite (HCM) in the Miocene Pohang-Youngduk Basin (PYB), providing an opportunity to differentiate the triggering events. This megaturbidite is over 70 m thick in the proximal part and less than 4 m thick in the distal part. The diachronous stratigraphic position and distinct coarser sediments than those of the underlying and overlying successions suggest a large-scale slope failure of the fine-grained foreset (more than 2 km3). The occurrence of exotic granitic boulders, originating from the basement rock, more than 1 km west of the present fan-apex, is indicative of extreme sea-level run-up. The dispersal pattern and paleocurrent direction suggest that the HCM flowed to the northeast, irrespective of the local depositional slope which show a radial distribution from the fan-apex. The distribution pattern almost perpendicular to the strike of the NW-SE trending transfer fault suggests that the HCM was triggered by a reflection flow of giant tsunami wave, resulting in a large-scale failure of high-gradient (> 15° in slope angle) fandelta slope. [ABSTRACT FROM AUTHOR]

The Makran subduction zone has historically experienced major earthquakes and tsunamis. Here, we integrate fault morphology, InSAR measurements, and high‐resolution bathymetry to quantitively evaluate potential future tsunami sources and tsunami wave characteristics. We systematically investigate how earthquake rupture speed and direction could affect tsunami hazards for the Makran region. Our analyses reveal the following new understanding: (1) The estimated maximum slip deficit in the Makran region southeast of the Gwadar port is >4 m since the last significant 1851 rupture; (2) Earthquakes with finite rupture speed investigated in the range of 300–1,000 m/s are calculated to generate higher tsunami waves than the static rupture model; (3) For an east‐to‐west rupture direction, the tsunami waves are calculated to arrive at the Gwadar port 3–5 mins later but with higher waves than the static rupture model. Together, our results highlight the importance of the source earthquake rupture speed and directivity in controlling tsunamigenic effects. [ABSTRACT FROM AUTHOR]

In this study, the double-difference tomography (tomoDD) method is applied to jointly invert the three-dimensional (3-D) crustal velocity structure and earthquake locations in the Maduo area based on automatically and manually picked seismic phase data. The results show that: (1) We speculated that the seismogenic fault is the Kunlun Pass–Jiangcuo Fault based on the spatial distributions of the aftershocks and surface rupture and the strike slip nature of the fault and the mainshock. In addition, a continuous northwest-trending branch fault may exist on the north side of the western section of the Maduo aftershocks. (2) We speculated that the Maduo earthquake was a bilateral rupture based on the media strength of the upper crust and near the surface and the seismic distribution. The findings also provide evidence for the large-scale rupture of the Maduo earthquake. In addition, the high-velocity body to the upper right of the mainshock satisfactorily explains the unobvious rupture above the mainshock. The late weak seismicity indicates that the energy released during the earthquake rupture was sufficient, and it is concluded that the short-term seismic hazard is insignificant. (3) The low S-wave velocity and high wave ratio reflect the existence of crustal fluids in the Maduo area based on the results of previous studies. The Maduo earthquake occurred on the side of the biased high-velocity body in the high-low velocity transition zone, where the stress easily accumulates and is easily released. Therefore, we conclude that the Maduo earthquake accumulated significant stress in the source area. The crustal fluids encountered a hard slope-type high-velocity body and flowed upward into the seismogenic fault, weakening the seismogenic fault. The combined effect of both processes finally triggered the Maduo MS7.4 earthquake. [ABSTRACT FROM AUTHOR]

We explored nonlinear effects within the context of tsunami waveform inversion, wherein Green's functions were linearly superimposed to estimate earthquake slips. We focused on these effects while developing a source model for the 2003 Tokachi–Oki earthquake off Hokkaido, Japan. A source model for this earthquake was developed based on linear tsunami waveform inversion using Green's functions and tsunami waveforms observed at tide gauge stations. Subsequently, tsunami waveforms from the source were simulated at the stations using nonlinear long-wave theory and compared with those estimated by inversion. The comparisons demonstrated that the waveforms had a non-negligible discrepancy that was attributed to advection effects, even for the primary wave used in the inversion at the two stations. This result strongly suggests that advection effects should be considered in the source modeling of the 2003 earthquake based on tsunami waveforms observed by tide gauges. Based on these results, a new tsunami waveform inversion technique that incorporates linearly approximated advection effects and maintain the framework of linear tsunami waveform inversion using Green's functions is proposed and applied. The proposed method successfully mimicked the advection effects during the 2003 tsunami, reproduced better tsunami waveforms, and developed a source model for the 2003 earthquake using these effects. The peak slip amount and seismic moment were greater in the source model with advection effects than those without the effects. This finding suggests that the values in the source models developed for other earthquake events without considering these effects may have been underestimated. [ABSTRACT FROM AUTHOR]

The increased velocity associated with decaying seismicity in the subducting oceanic crust usually has been attributed to its eclogitization. However, the degree of the eclogitization of subducting oceanic crust at depth remains unclear due to the lack of velocity data for eclogite at pressures of >3 GPa. In this study, the P- and S-wave velocities of eclogite aggregates composed of omphacite and garnet (Omp100, Omp80Grt20, and Omp- 50Grt50) were measured simultaneously at pressures of up to 8 GPa using ultrasonic interferometry. The velocities of the eclogite aggregates increased with rising pressure and garnet content. By determining the velocities at different pressures using the finite strain equation, the elastic moduli of the eclogites and their pressure derivatives were determined to be KS0 = 119-134 GPa, KS0‰ = 5.2-5.3, G0 = 73-80 GPa, and G0‰ = 1.5-1.6. The high-wave velocity and low VP/VS ratio of the eclogites, combined with the seismic tomography and seismicity distribution, jointly constrain the depth and composition of eclogitization in the subducted oceanic crust of Northeast Japan, and a new 1-D velocity structure is proposed. We also compiled and calculated the depth of the eclogitization and the garnet content of the subducting oceanic crusts in 27 typical locations around the Pacific Ocean. The depth of the eclogitization was positively correlated with the age of the subduction zone, and the garnet content was estimated to be 12%-32% in our model. [ABSTRACT FROM AUTHOR]

Landslides are a severe geohazard around the world. When moving soil masses discharge into a large water body, a tsunami can be generated and exacerbate the devastating effects of the landslide as well as extend the affected area. In this study, based on on-site geological investigation and monitoring, a numerical depth-averaged, two-phase model is established for a hypothetical tsunami in the Suofengying reservoir induced by the potential Bianjiazhai landslide in China which has been previously identified as critical. The analysis of the simulation results shows that the maximum wave amplitude measured at gauge point closest to the landslide is 31 m, and the tsunami reaches the reservoir's dam about 66 s after the landslide initiation. The inundation map provides potential risk areas that could be affected if a landslide occurs with the anticipated characteristics. Under similar conditions, the research results will help guide reservoir operation and landslide-tsunami disaster prevention. Simultaneously, examining the sequence of events in the tsunami disaster chain facilitates the analysis of the fundamental physics governing the propagation of tsunamis within reservoirs. This analysis contributes to the prediction and prevention of landslide-induced tsunami disasters occurring along reservoir banks. [ABSTRACT FROM AUTHOR]

Subduction earthquakes show complex spatial and temporal rupture patterns, exhibiting events of varied sizes, which rupture distinct or overlapping fault segments. Elucidating first-order controlling conditions of rupture segmentation and return periods of large earthquakes is therefore critical for seismic and tsunami hazard estimations. The Chilean subduction zone frequently hosts several M w > 8 earthquakes, with heterogeneous recurrence rates and locations. Here, we implement 3-D quasi-dynamic rate and state frictional models to investigate the role of plate interface geometry on the distribution of interseismic coupling and coseismic ruptures in Central Chile. First, we develop synthetic-parametric models that show how dip and strike variations may increase the probabilities to produce partial seismic barriers, which tend to avoid the production of large earthquake ruptures and modulate rupture lengths. Then, we simulate the subduction seismic cycle processes on Central Chile (25°S–38°S), imposing depth-dependent frictional properties on a realistic non-planar 3-D subduction interface geometry. Similar to results obtained for synthetic-parametric models, after 5000 yr of simulation, regions with abrupt dip or strike changes increase the probabilities of stopping coseismic propagation of simulated M w 8.0–9.0 earthquakes. Our simulated earthquake sequences on the Central Chile subduction zone delimit rupture areas that match geometrical interface features and historical earthquakes, results that point to the crucial role of fault interface geometry on seismic cycle segmentation along strike. [ABSTRACT FROM AUTHOR]

Tsunamis continue to pose an existential threat to life and infrastructure in many coastal areas around the world. One of the risks associated with tsunamis is the formation of deep scour holes around critical infrastructure and other coastal buildings, compromising their structural integrity and stability. Despite its importance, tsunami-induced scour is still given limited and simplified consideration in design guidelines for coastal structures. To further improve the understanding of tsunami-induced scour processes, and thus provide the basis for safer design of coastal structures, novel large-scale laboratory experiments have been conducted. The experiments featured a unique combination of boundary conditions, including a square coastal structure on a sloping and dry sandy beach. Single broken solitary waves were used to simulate tsunami bores. The spatiotemporal scour development directly at the square column was monitored by a high-resolution camera system, allowing a detailed description of the highly dynamic flow and scour process. Differences in the scour process between the wave runup and drawdown phases are described, and maximum and final scour depths are given as a function of inundation depth, wave height, and distance of the column from the shoreline. The scour process is characterized by several distinct phases of varying intensity and scour rate, the sequence of which varies depending on the location on the sides of the column. It is shown that the drawdown phase has a large influence on the overall scour development, adding up to 58% to the scour depth obtained during the wave runup phase. As a result of significant sediment infilling during the drawdown phase, the maximum scour depths achieved during the drawdown phase are up to twice the final scour depths at the end of a test. This discrepancy between final and maximum scour depths is greater than in previous studies using a flat sediment bed. The results of this study therefore help to interpret scour depths measured during field investigations after a tsunami event and provide a basis for extending design guidelines for coastal structures. [ABSTRACT FROM AUTHOR]

A novel coupled approach to modeling various stages of waves generated by different types of landslides (e.g., subaerial to submerged) through divergence-free incompressible smoothed particle hydrodynamics (ISPH) was developed in this study. In this approach, coexisting fluid and granular modules interact with each other through an interaction force pair, which necessitates the accurate transfer of information related to the fluid stress tensor and velocity vectors of the complementary module. A support domain centering each particle of both phases along with specific corrective treatments caters to the averaging of information from the complementary module. The model was tested against three scenarios (with limiting criteria such as suspended load transport and hindrance to porosity conceptualization) ranging from subaerial to submerged granular slides and resulting water surface fluctuations. [ABSTRACT FROM AUTHOR]

Geological evidence, such as tsunami deposits, is crucial for studying the largest rupture zone of the Kuril Trench in Hokkaido, Japan, due to its poor historical record. Although 17th-century tsunami deposits are widely distributed across Hokkaido, the presence of multiple wave sources during that period, including the collapse of Mt. Komagatake, complicates the correlation with their wave sources. Understanding the regional distribution of these tsunami deposits can provide valuable data to estimate the magnitude of megathrust earthquakes in the Kuril Trench. The northern part of Hidaka, Hokkaido, where tsunamis from multiple wave sources are expected to overlap, is distant from the Kuril Trench. To clarify the depositional history of tsunami deposits in such distal areas, evaluating the influence of the depositional environments on the event layer preservation becomes even more critical. We conducted field surveys in Kabari, located in the northern Hidaka region, identifying three sand layers from the 10th to the 17th century and two layers dating beyond 2.3 thousand years ago. The depositional ages of most sand layers potentially correlate with tsunami deposits resulting from the Kuril Trench earthquakes. Utilizing reconstructed paleo-sea level data, we estimated that most sand layers reached approximately 2 m in height. However, it is noteworthy that the latest sand layer from the 17th century exhibited an unusual distribution, more than 3 m in height. This suggests a different wave source as the Mt. Komagatake collapse. The discovery of multiple sand layers and their distributions is crucial to constraining the maximum magnitude of giant earthquakes in the Kuril Trench and understanding the volcanic tsunami events related to Mt. Komagatake. [ABSTRACT FROM AUTHOR]

Converging evidence supports the involvement of circadian rhythm disturbances in the course and morbidity of bipolar disorders (BD). During 2020, lockdown measures were introduced worldwide to contain the health crisis caused by the COVID-19 pandemic. As a result, chronobiological rhythms were critically disrupted and illness outcomes were expected to worsen. The current study aimed to explore changes in morbidity among BD patients living under lockdown. Ninety BD outpatients under naturalistic treatment conditions were followed from March to September 2020 using a mood chart technique. Different treatment and illness variables, including mood instability, were assessed and compared with the outcomes obtained during the same 28-week period in 2019. For most clinical variables, no significant differences were observed between time periods. A slight decrease was found in symptom intensity (from 15.19 ± 20.62 to 10.34 ± 15.79, FDR-adjusted p = 0.04) and in the number of depressive episodes (from 0.39 ± 0.74 to 0.22 ± 0.63, FDR-adjusted p = 0.03), whereas the intensity of pharmacological treatment remained unchanged. Previous illness course predicted mood outcomes during the confinement. Follow-up periods were relatively short. Further, actigraphy or other methods capable of ensuring significant changes in physical activity were not used. In line with other studies, our findings show no worsening in the clinical morbidity of BD patients during lockdown. This conspicuous contrast between our initial predictions and the observed findings highlights the fact that we are still far from being able to provide accurate predictive models for BD. • During COVID-19 lockdowns, daily rhythms and care access of people affected by bipolar disorder (BD) were critically disrupted. • This context provides the opportunity to explore the impact of these stressors on illness course. • In this sample, BD patients didn't show increments in any of the morbidity parameters assessed during a long strict lockdown. • At present, it is not possible to make reliable predictions regarding the impact of these illness stressor in short-term clinical evolution of BDs. [ABSTRACT FROM AUTHOR]

The Hunga Tonga–Hunga Ha'apai volcanic eruption on January 15, 2022 generated a tsunami that affected the entire Pacific Ocean. Tsunami waves from the event have been generated both by incoming waves from the source area with a long-wave speed in the ocean of ~200–220 m/s, and by an atmospheric wave propagating at a sound speed of ~315 m/s. Such a dual source mechanism created a serious problem and was a real challenge for the Pacific tsunami warning services. The work of the Russian Tsunami Warning Service (Yuzhno-Sakhalinsk) during this event is considered in detail. The tsunami was clearly recorded on the coasts of the Northwest Pacific and in the adjacent marginal seas, including the Sea of Japan, the Sea of Okhotsk, and the Bering Sea. We examined high-resolution records (1-min sampling) of 20 tide gauges and 8 air pressure stations in this region for the period of January 14–17, 2022. On the Russian coast, the highest waves, with a trough-to-crest wave height of 1.3 m, were recorded at Malokurilskoe (Shikotan Island) and Vodopadnaya (southeastern coast of Kamchatka). Using numerical simulation and data analysis methods, we were able to separate oceanic "gravity" tsunami waves from propagating atmospheric pressure waves. In general, we found that on the outer (oceanic) coasts and southern coast of the Sea of Okhotsk, oceanic tsunami waves prevailed, while on the coast of the Sea of Japan, oceanic and atmospheric tsunami waves had similar heights. [ABSTRACT FROM AUTHOR]

Waves can induce motion in the floating platforms that support tidal turbines, affecting their hydrodynamic loads. To study the non-constant hydrodynamic of floating tidal turbines in a wave condition, this paper investigates the effect of pitch motion on the power coefficient (CP), thrust coefficient (CT), and wake flow of a tidal turbine using computational fluid dynamics. A pitch motion experiment is designed to verify the validity of the numerical method. The results show that the CP and CT exhibit periodic fluctuations under pitch motion, with the fluctuation period being consistent with the pitch period. Waves do not change the overall fluctuation trend of the CP and CT, but they do complicate the fluctuations and increase the likelihood of blade fatigue damage. Pitch motion reduces the mean power, with large-amplitude pitch motions particularly likely to result in severe power loss. The low-velocity region of the wake under pitch motion exhibits significant periodic oscillations. The wake is more susceptible to the pitch period than the pitch amplitude, and small-period pitch motions force the wake to deform earlier, accelerating wake vortex dissipation and velocity recovery. Increasing the immersion depth reduces the effect of waves on tidal turbine performance, but is not conducive to wake recovery. In summary, the rational design of the immersion depth and limiting the movement amplitude of the floating platform have the potential to prolong the working life of tidal turbines and increase their power output. [ABSTRACT FROM AUTHOR]

Nonhydrostatic models have proven their superiority in describing tsunami propagation over trans-oceanic distances and nearshore transformation because of their good dispersion and nonlinearity properties. The novel one-layer nonhydrostatic formulations proposed by Wang et al. [Phys. Fluids 35, 076610 (2023)] have been rederived in the spherical coordinate system incorporating Coriolis effects to enable the application of basin-wide tsunami propagation. The model was implemented using the fractional step method, where the hydrostatic step was solved by a Godunov-type finite-volume scheme, and the nonhydrostatic step was obtained with the finite-difference method. Additionally, a two-way grid-nesting scheme was employed to adapt the topographic features for efficient computation of tsunami propagation in deep ocean and coastal inundation. Furthermore, graphics processing unit (GPU)-parallelism technique was incorporated to further optimize the model performance. An idealized benchmark test as well as three experiments of regular and irregular waves, solitary, and N-waves transformations have been simulated to demonstrate the superior performance of the current GPU-accelerated grid-nesting nonhydrostatic model. Finally, the model has been applied to reproduce the 1964 Prince William Sound Tsunami, its propagation across the North Pacific and induced inundation in the Seaside. [ABSTRACT FROM AUTHOR]

This article discusses the problem of generating internal waves during explosive eruptions of underwater volcanoes. The importance and novelty of such studies are associated with the emerging data on the observation of internal waves during a volcanic eruption in the Tonga Archipelago in 2022 reported in Zhang and Li ["Oceanic internal waves generated by the Tongan volcano eruption," Acta Oceanol. Sin. 41(8), 1–4 (2022)]. Using Le Méhaute's parametric model originally suggested to calculate surface waves, internal waves in the ocean with a constant buoyancy frequency are calculated. Internal waves are trains of different modes, the parameters of which were found for different ratios between the radius of the equivalent source and the depth of the basin. Even at relatively small distances from the source (tens of km), wave amplitudes changeover time periods consisting of several days, which confirms the possibility of delineating the tsunami source by internal waves. [ABSTRACT FROM AUTHOR]

To understand the characteristics of seismic waves and tsunamis recorded simultaneously by the ocean-bottom observation networks, the coupling between the solid Earth and the ocean has to be modeled in the presence of gravity. However, previous coupled simulations adopted approximate equations that did not fully incorporate the effects of gravity. In this study, we derived correctly linearized governing equations under gravity and compared them with those of previous studies. Numerical experiments were performed for a two-dimensional P-SV wavefield, using the finite difference method (FDM). To validate the accuracy of the calculated tsunamis, we computed the theoretical tsunami dispersion relation using a propagator matrix and compared it with our results and those of previous studies. We found that our proposed method provided more accurate results than those of previous studies, particularly in the short-period band. We also investigated the applicability of the proposed method to distant tsunamis by examining the difference between calculated and theoretical tsunami phase velocities in the long-period band. The proposed formulation provides accurate results that properly incorporate gravity into the simultaneous simulation of seismic waves and tsunamis. [ABSTRACT FROM AUTHOR]

In the context of the 2022 volcanic explosion in Tonga, we investigate the structure of the fundamental elasto-gravitational branch G R 0 of air waves, and especially their coupling to an oceanic column of variable depth. We find that the structure of the wave in the atmosphere, in particular the overpressure component of its eigenfunction, is essentially independent of the presence and depth of an oceanic layer; normal mode theory predicts that its excitation by an explosive source in the atmosphere is also independent of water depth. The impedance of G R 0 , defined as the ratio of vertical displacement of the sea surface to overpressure at the base of the atmosphere, increases strongly with water depth and varies only marginally with frequency. It can become negative for very shallow depths and very low frequencies, but takes its classical hydrostatic value of 1 cm/mbar only for a ∼ 5-km deep ocean. This results in minimal maregraphic amplitudes, and hence flooding hazard, during the passage of G R 0 over very shallow seas. Finally, we find that the ratio of the sea surface displacement to the pressure signal on the seafloor, as measured for example by sensors of the DART network, increases strongly with ocean depth, but never reaches its hydrostatic value (1 cm/mbar or 10 - 4 m/Pa). In this respect, the present DART protocol in which the hydrostatic ratio is hardwired into the reporting algorithm could be considered deceptive, and should be revised. [ABSTRACT FROM AUTHOR]

The recent destructive landslide tsunamis, such as the 2018 Anak Krakatau event, were fresh reminders for developing validated three-dimensional numerical tools to accurately model landslide tsunamis and to predict their hazards. In this study, we perform Three-dimensional physical modelling of waves generated by subaerial solid-block landslides, and use the data to validate two numerical models: the commercial software FLOW-3D HYDRO and the open-source OpenFOAM package. These models are key representatives of the primary types of modelling tools—commercial and open-source—utilized by scientists and engineers in the field. This research is among a few studies on 3D physical and numerical models for landslide-generated waves, and it is the first time that the aforementioned two models are systematically compared. We show that the two models accurately reproduce the physical experiments and give similar performances in modelling landslide-generated waves. However, they apply different approaches, mechanisms and calibrations to deliver the tasks. It is found that the results of the two models are deviated by approximately 10% from one another. This guide helps engineers and scientists implement, calibrate, and validate these models for landslide-generated waves. The validity of this research is confined to solid-block subaerial landslides and their impact in the near-field zone. [ABSTRACT FROM AUTHOR]

Despite evacuation on foot being recommended by authorities, evacuation in practice is assumed to include evacuation on foot and evacuation by car, as a certain amount of evacuation by car is to be expected. We developed a tsunami evacuation training application operating on smartphones and tablets, and a tsunami evacuation training simulator to evaluate the effect of this application. We then conducted an experiment in Nishio City to evaluate the application. We found that the subjects were able to quickly grasp the attention targets that were present near them but had difficulty grasping attention targets that were far away. This suggests that participants need to be trained repeatedly on distant objects of attention to be able to locate them instantaneously. [ABSTRACT FROM AUTHOR]

This article provides an overview of the advancements in artificial intelligence (AI) over the years. It highlights significant milestones such as the chess match between Gary Kasparov and IBM's DeepBlue supercomputer, as well as the development of AlphaGo and AlphaZero for the game of Go. The article also mentions AlphaFold, a program that predicts protein structures, and the Transformer Neural Network Architecture, which revolutionized natural language processing. It concludes by discussing the recent popularity of large language models like ChatGPT, which can generate coherent responses to text prompts in multiple languages. However, it notes that ChatGPT lacks an understanding of the meaning behind the symbols it generates, and its accuracy improves over time through learning from input. [Extracted from the article]

Every fluid problem is greatly affected by its boundary conditions, especially the near-shore seabed could produce an irrevocable harm when a tsunami wave is approaching, and a real-life mathematical model could stave off the worst effect. This paper assumes that the unsmooth seabed is a fractal surface, and fractal-fractional governing equations are established according to physical laws in the fractal space. The geometrical potential theory is used to explain the force produced by the wave surface, and Kong-He friction law is applied to further figuring out the local and memory properties of the friction along the fractal boundary. This paper aims at studying tsunami waves in a fractal space, rendering a reliable mathematical model for both prediction of the tsunami motion and the coastal protection. [ABSTRACT FROM AUTHOR]

An understanding of the geomorphological processes instigated by seismic-related catastrophes such as tsunamis is important to our understanding of their potential impacts on both past and present human populations. Due to the relative scarcity of human records of such events in prehistory, it is necessary to rely on the geological record to identify and interpret the environmental changes caused by such catastrophes. A multi-proxy analysis of geological and geomorphological data is used to identify a local signal of a region-wide 15th century palaeotsunami that inundated the SW North Island coast of Aotearoa/New Zealand. A comparison with regional geological and archaeological evidence enriches our understanding of the nature and extent of this event and its impact on human settlement that complements similar findings in other countries. [ABSTRACT FROM AUTHOR]

Plate-coupling estimates and previous seismicity indicate that portions of the Makran megathrust of southern Pakistan and Iran are partially coupled and have the potential to produce future magnitude 7+ earthquakes. However, the GPS observations needed to constrain coupling models are sparse and lead to an incomplete understanding of regional earthquake and tsunami hazard. In this study, we assess GPS velocities for plate coupling of the Makran subduction zone with specific attention to model resolution and the accretionary prism rheology. We use finite element model-derived Green's functions to invert for the interseismic slip deficit under both elastic and viscoelastic Earth assumptions. We use the model resolution matrix to characterize plate-coupling scenarios that are consistent with the limited spatial resolution afforded by GPS observations. We then forward model the corresponding tsunami responses at major coastal cities within the western Indian Ocean basin. Our plate-coupling results show potential segmentation of the megathrust with varying coupling from west to east, but do not rule out a scenario where the entire length of the megathrust could rupture in a single earthquake. The full subduction zone rupture scenarios suggest that the Makran may be able to produce earthquakes up to M w 9.2. The corresponding tsunami model from the largest earthquake event (M w 9.2) estimates maximum wave heights reaching 2–5 m at major port cities in the northern Arabian Sea region. Cities on the west coast of India are less affected (1–2 m). Coastlines bounding eastern Africa, and the Strait of Hormuz, are the least affected (<1 m). [ABSTRACT FROM AUTHOR]

Using a Bayesian approach we compare anecdotal tsunami runup observations from the 29 December 1820 Flores Sea earthquake with close to 200 000 tsunami simulations to determine the most probable earthquake parameters causing the tsunami. Using a dual hypothesis of the source earthquake either originating from the Flores Thrust or the Walanae/Selayar Fault, we found that neither source perfectly matches the observational data, particularly while satisfying seismic constraints of the region. Instead both posteriors have shifted to the edge of the prior indicating that the actual earthquake may have run along both faults. [ABSTRACT FROM AUTHOR]

Despite alarming predications about the Covid 19 pandemic that appear to fit the literature on the impact of natural disasters on civil wars, there are reasons to be suspicious that a rise in militant violence would likely occur quickly or uniformly. Although the COVID-19 pandemic is most definitely a disaster that caught the world by surprise, this "slow-rolling" shock differs in important ways from the more commonly studied acute onset natural disasters such as earthquakes, hurricanes, and tsunamis that often increase violent competition among groups for scarce resources. Instead, the effects of slow-rolling disasters unfold in phases that, at least in the short run, are likely to encourage a period of relative decline in violence, as actors try and assess the effects of COVID-19 on their organization and their opponents. Both statistical and qualitative evidence from the initial months of the COVID-19 pandemic supports the initial phases of our theory. [ABSTRACT FROM AUTHOR]

The 1 January 2024 Noto-Hanto (Noto Peninsula) earthquake (MJMA 7.6) generated strong ground motion, large crustal deformation and tsunamis that caused significant damage in the region. Around Noto Peninsula, both offshore submarine and partially inland active faults have been identified by previous projects: Ministry of Land, Infrastructure, Transport and Tourism (MLIT) and Japan Sea Earthquake and Tsunami Research Project (JSPJ). We inverted the tsunami waveforms recorded on 6 wave gauges and 12 tide gauges around Sea of Japan and the GNSS data recorded at 53 stations in Noto Peninsula to estimate the slip amount and seismic moment on each of active faults. The results show that the 2024 coseismic slips were 3.5 m, 3.2 m, and 3.2 m on subfaults NT4, NT5 and NT6 of the JSPJ model, located on the northern coast of Noto Peninsula and dipping toward southeast. A smaller slip, 1.0 m, estimated on NT8 on the southwestern end of the 2024 rupture, may be attributed to its previous rupture during the 2007 Noto earthquake. The total length of these four faults is ~ 100 km, and the seismic moment is 1.90 × 1020 Nm (Mw = 7.5). Almost no slip was estimated on the northeastern subfaults NT2 and NT3, which dip northwestward, opposite to NT4–NT5–NT6, and western subfault NT8. Aftershocks including the MJMA 6.1 event occurred in the NT2–NT3 region, but they are smaller than the potential magnitude (Mw 7.1) those faults can release in a tsunamigenic earthquake. Similar features are also found for the MLIT model; the 2024 slip was only on F43 along the northern coast of Noto Peninsula, and northeastern F42 did not rupture, leaving potential for future event. [ABSTRACT FROM AUTHOR]

Digital twins of physical and human systems informed by real-time data are becoming ubiquitous across weather forecasting, disaster preparedness, and urban planning, but researchers lack the tools to run these models effectively and efficiently, limiting progress. One of the current challenges is to assimilate observations in highly non-linear dynamical systems, as the practical need is often to detect abrupt changes. We have developed a software platform to improve the use of real-time data in non-linear system representations where non-Gaussianity limits the applicability of data assimilation algorithms such as the ensemble Kalman filter and variational methods. Particle-filter-based data assimilation algorithms have been implemented within a user-friendly open-source software platform in Julia – ParticleDA.jl. To ensure the applicability of the developed platform in realistic scenarios, emphasis has been placed on numerical efficiency and scalability on high-performance computing systems. Furthermore, the platform has been developed to be forward-model agnostic, ensuring that it is applicable to a wide range of modelling settings, for instance unstructured and non-uniform meshes in the spatial domain or even state spaces that are not spatially organized. Applications to tsunami and numerical weather prediction demonstrate the computational benefits and ease of using the high-level Julia interface with the package to perform filtering in a variety of complex models. [ABSTRACT FROM AUTHOR]

Submarine landslides are significant geohazards, capable of displacing large volumes of sediment from continental margins to deposit mass transport complexes (MTCs) and generate offshore tsunamis. However, the reactivation of MTCs after their initial failure has long been overlooked. By analyzing high-quality three-dimensional seismic reflection data and seismic attribute maps, as well as comparing the geometry of different MTCs, we investigate the development of long-term slope instability and its hazardous consequences on the northwest flank of the Storegga Slide on the Norwegian margin. Our results demonstrate that the reactivation of MTCs can deform both their inner structure and overlying strata, promoting the formation of sinuous channels and local slope failures on the seafloor. These findings further reveal the MTCs that are underconsolidated or comprise slide blocks may remain unstable for a long time after their initial failure, particularly when affected by slope undercutting and a corresponding reduction in lateral support. This study shows that MTCprone sequences are more likely to comprise regions of continental slopes with long-term instability and recurring marine geohazards. [ABSTRACT FROM AUTHOR]

The past offers important lessons with regard to facing the future with greater awareness. In this context, school plays a key role in spreading knowledge of natural phenomena and in promoting behavior change. Together with researchers, teachers can be strong allies to build more resilient future citizens. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) school training activities provide tools to prepare for the next earthquake and/or tsunami. Approximately 5000 students, from both middle schools (ISCED 2) and high schools (ISCED 3), were involved in active learning activities based on a flipped-up approach during specific online scientific events during the pandemic. Online lab activities were conducted during European Researchers' Night ("Earthquakes: history teaches us the future: researchers for a day with experimentation in didactics for ESL") and during both World Water Day 2021 and World Earth Day 2021 ("Tsunamis: history teaches us the future researchers for a day with experimentation in didactics for ESL"). These two Episodes of Situated Learning (ESL) experiences triggered students' interest, favoring remote learning, developing life skills, and focusing on historical seismic studies of both past earthquakes and tsunamis. [ABSTRACT FROM AUTHOR]

Models of near‐field tsunamis and an extreme hurricane provide further evidence for a great precolonial earthquake along the Puerto Rico Trench. The models are benchmarked to brain‐coral boulders and cobbles on Anegada, 125 km south of the trench. The models are screened by their success in flooding the mapped sites of these erratics, which were emplaced some six centuries ago. Among 25 tsunami scenarios, 19 have megathrust sources and the rest posit normal faulting on the outer rise. The modeled storm, the most extreme of 15 hurricanes of category 5, produces tsunami‐like bores from surf beat. In the tsunami scenarios, simulated flow depth is 1 m or more at all the clast sites, and 2 m or more at nearly all, given either a megathrust rupture 255 km long with 7.5 m of dip slip and M8.45, or an outer‐rise rupture 130 km long with 11.4 m of dip slip and M8.17. By contrast, many coral clasts lie beyond the reach of simulated flooding from the extreme hurricane. The tsunami screening may underestimate earthquake size by neglecting trees and shrubs that likely impeded both the simulated flows and the observed clasts; and it may overestimate earthquake size by leaving coastal sand barriers intact. The screening results broadly agree with those from previously published tsunami simulations. In either successful scenario, the average recurrence interval spans thousands of years, and flooding on the nearest Caribbean shores begins within a half‐hour. Plain Language Summary: Has a tsunami ever resulted from fault rupture on or near the tectonic plate boundary north of Puerto Rico and the Virgin Islands? Although no such tsunami is known from five centuries of written history, a sea flood some six centuries ago stranded coral heads hundreds of meters inland on Anegada, the northernmost of the British Virgin Islands. Here, using numerical models, we ask whether this pre‐Columbian flood was a near‐field tsunami or an outsize hurricane. The modeled storm waves produce tsunami‐like bores but flood a minority of the coral clasts. Twenty‐five tsunami scenarios differ in their success in flooding, to depths of 1 and 2 m, the mapped sites of 171 brain‐coral clasts. The successful tsunami scenarios correspond to great Puerto Rico Trench earthquakes larger than magnitude 8.0, either on a gently inclined plate boundary or on a steep fault within the incoming oceanic plate. The earthquake recurrence interval in either case lasts thousands of years, but catastrophic flooding on near‐source islands begins within a few tens of minutes. Key Points: In simulations for a low Caribbean island, near‐field tsunamis account for coral boulders and cobbles that an extreme hurricane does notAt all these clasts, flow depths are >1 m for great earthquakes along the Puerto Rico Trench, both on the outer rise and on the megathrustThe tsunami in either case reaches many shores within an hour of the parent earthquake [ABSTRACT FROM AUTHOR]

Tsunami simulations require powerful computational resources to be performed efficiently. Although the modern graphics processing units (GPUs) allow the acceleration of this kind of simulations, they can still last many minutes or even hours for simulations which have to deal with very high spatial resolutions or simulation times. In this paper, we propose a method to predict the alert or inundation level of a tsunami generated by an earthquake using deep learning methods. In particular, we train multilayer perceptron (MLP) neural networks for predicting the alert level due to a tsunami at given coastal locations. Ensemble methods are used to improve the predictions of the neural networks. Tsunamis caused by ruptures of several fault segments at different time instants, application to real events, probabilistic forecasting and comparison with other machine learning algorithms are also addressed. Results on realistic scenarios confirm that good accuracies are obtained. The inference times of the trained networks and ensembles are also very low, lasting less than one second to predict the results of thousands of simulations. The proposed method could be used in a tsunami early warning system along with the application of scaling laws. Plain Language Summary: In tsunami early warning systems (TEWS) it is crucial to perform fast predictions of the risk of a tsunami in coastal areas in order to take appropriate measures before the arrival of the tsunami. Currently, tsunami simulations may take many minutes or even hours despite using modern computational resources. In this work we propose a method based on deep learning techniques to predict the alert level of a tsunami generated by an earthquake at given coastal locations in a fraction of a second. This method could be used in TEWS along with techniques to estimate the values of some parameters of the earthquake. Application to real events and probabilistic predictions are also addressed. Key Points: A deep learning method to predict different tsunami alert levels is proposedTsunamis caused by the rupture of multiple fault segments at different time instants are supportedApplication to real events with probabilistic predictions are addressed [ABSTRACT FROM AUTHOR]

Oceanic mixing, mostly driven by the breaking of internal waves at small scales in the ocean interior, is of major importance for ocean circulation and the ocean response to future climate scenarios. Understanding how internal waves transfer their energy to smaller scales from their generation to their dissipation is therefore an important step for improving the representation of ocean mixing in climate models. In this study, the processes leading to cross-scale energy fluxes in the internal wave field are quantified using an original decomposition approach in a realistic numerical simulation of the California Current. We quantify the relative contribution of eddy–internal wave interactions and wave–wave interactions to these fluxes and show that eddy–internal wave interactions are more efficient than wave–wave interactions in the formation of the internal wave continuum spectrum. Carrying out twin numerical simulations, where we successively activate or deactivate one of the main internal wave forcing, we also show that eddy–near-inertial internal wave interactions are more efficient in the cross-scale energy transfer than eddy–tidal internal wave interactions. This results in the dissipation being dominated by the near-inertial internal waves over tidal internal waves. A companion study focuses on the role of stimulated cascade on the energy and enstrophy fluxes. [ABSTRACT FROM AUTHOR]

Asteroid impacts can cause a wide range of damage through multiple potential hazards, from localized blast waves or thermal radiation, to tsunami inundation, to global climatic effects. The level of risk posed by these hazards depends not only upon their extent and severity, but also upon the likelihood of the various damage ranges. Some consequences may be more moderate but very likely, while others may be unlikely but catastrophic. Evaluating the risk from these hazards involves substantial uncertainties across all aspects of the problem, including the properties of the asteroid, the specifics of its entry, and the complex high-energy damage physics involved. NASA's Asteroid Threat Assessment Project (ATAP) performs Probabilistic Asteroid Impact Risk (PAIR) assessments that use fast-running entry and hazard models to evaluate millions of impact cases representing the distributions of these many uncertain parameters. This paper presents the current PAIR modeling tools and approaches used for evaluating specific asteroid impact threat cases. We give an overview of the current PAIR model used to support hypothetical impact threat scenarios and discuss some of the key applications of these assessment in supporting planetary defense response and preparedness. We then present the results and key findings from the recent 2023 PDC hypothetical impact exercise as an example of the primary types of risk results and metrics being developed to inform potential mitigation and response decisions. The 2023 PDC scenario represents an impact threat from a large 800-m asteroid with an initial uncertain size range from ∼150 m to 2 km in diameter, spanning sizes that would cause only local damage to sizes that could potentially cause tsunamis or global effects. Results demonstrate key assessment and response challenges for such large impact scenarios, and motivate the need for further modeling and simulation studies to better understand the potential onset and severity of regional and global-scale hazards. • Probabilistic risk assessments support response decisions for asteroid threats. • Assessment of the 2023 PDC impact scenario demonstrated key response challenges. • Global effects were a major risk driver despite their low probability. • Asteroid size and damage uncertainties underscore the need for rapid space missions. • Results motivate simulation studies of large impact hazards to improve risk estimates. [ABSTRACT FROM AUTHOR]

The devastating consequences of tsunamis on coastal infrastructure have highlighted the urgent need for effective disaster risk reduction strategies. To mitigate tsunami disasters, the insurance industry plays a vital role in implementing risk transfer measures by providing financial protection against asset damage. However, the current research on catastrophe insurance policies for coastal infrastructure lacks consideration of climate change effects. It is essential to take into account the non-stationary effects of sea-level rise to develop long-term tsunami disaster mitigation measures and promote socioeconomic resilience in coastal communities. This paper aims to provide an insurance portfolio optimization framework for coastal residential buildings subjected to tsunamis considering non-stationary sea-level rise effects based on a stochastic simulation approach. A spatiotemporal probabilistic sea-level rise hazard assessment is carried out by utilizing available climate models and considering several emission scenarios. Tsunami propagation analyses under various sea-level rise cases are performed to evaluate the time-variant tsunami hazard curves based on Monte Carlo simulation. A life cycle-based stochastic insurance claim model associated with the cumulative loss of building assets is developed based on a non-stationary compound renewal process. Finally, a sample average approximation method is leveraged to estimate the optimum basic insurance premium rate by maximizing the insurer's profit under a cost-constrained insurance purchase decision of homeowners. As a case study, the proposed framework is applied to multiple municipalities situated in the tsunami-prone region of Kochi Prefecture, Japan. Sea-level rise substantially decreases the maximum profits of tsunami insurers and increases the premium rate and ruin probability. [ABSTRACT FROM AUTHOR]

Addressing the challenge of real-time estimation of instantaneous sound speed profiles (SSP for short). We proposes a SSP inversion method based on the travel time of vertically launched sound waves from seafloor stations to the sea surface. The basic principles of the inversion method are introduced, followed by an investigation into the calculation of instantaneous SSP area considering tidal and wave effects. The proposed method is validated by using semi-experimental data, the results indicate that the accuracy of predictions is poor if the correcting for the tidal and wave influences are not taken. However, after applying the correction equation proposed in this study to adjust for travel time, the relative error in the prediction of SSP area difference is less than 4%. [ABSTRACT FROM AUTHOR]

Tsunamis are a significant coastal hazard that pressurise sediment pore water, which can potentially induce liquefaction, enhance erosion and scour, and undermine the stability of beach sediments supporting natural and built infrastructure in the coastal nearshore environment. Tsunami-induced pressurisation of pore water is attributed to (a) mechanical pressurisation associated with the soil skeleton's tendency to contract or expand around the soil's pore fluid under the changing overlying water weight and (b) seepage of tsunami water into and out of the sand bed. The pore fluid compressibility, which is influenced by air entrainment due to water table fluctuations caused by the tides, can significantly influence development of stabilising and destabilising hydraulic gradients during tsunami runup and drawdown, respectively. Previous work has effectively assumed a constant air content in sand beds and neglected (a) the compression and dissolution of entrained air that influences the pore fluid compressibility and (b) the interaction between saturated sediment underlying sediment with entrained air. By considering the gas kinetics influencing the pore fluid compressibility in a seepage–deformation model, the effect of different pore fluid compressibility assumptions, thickness of sediment with entrained air, initial degree of saturation and tsunami wave properties (height and duration) were studied. The thickness of sediment containing entrained air, the assumed pore fluid compressibility assumption and subtle differences in the initial degree of saturation can significantly influence the predicted maximum depth and duration of tsunami-induced liquefaction. [ABSTRACT FROM AUTHOR]

The effect of non-uniform, oscillating bottom profiles on a two-layer stable density stratification model has been examined using the method of weakly non-linear analysis. The study of bottom profiles in the context of two-layered stratified fluids has focused on three specific types: (a) profiles that exhibit a monotonically decreasing pattern, (b) profiles that decay exponentially, and (c) profiles that display Gaussian oscillations. The analysis of the second-order reflection and transmission coefficients for the nonlinear boundary value problem was conducted using a combination of the regular perturbation method and the Fourier transforms technique. The numerical findings pertaining to various physical parameters have been presented, demonstrating the impact of the Class I Bragg resonance in all three profiles and the elevation of the tails in the monotonically decreasing oscillatory profile. Specifically, the presence of high reflections due to the tail-lifting phenomenon is observed in a profile that exhibits a monotonically decreasing pattern, in contrast to the other profiles. The findings of the study indicate that interface modes demonstrate pronounced reflections when the density ratios are low, but divergent results are observed when the density ratios are high. As the density ratio R increases, there is a greater migration of wave energy from the interface mode to the surface mode, resulting in increased levels of reflection. As the value of R approaches 1, it is observed that lower frequencies exhibit significantly more pronounced internal mode reflections compared to surface mode. Several contrasting aspects can be observed in three oscillatory profiles when compared to periodic profiles. These aspects include the disappearance of zero reflection, also known as complete transmission, as well as the absence of oscillations. The findings of this study demonstrate that a monotonically oscillating decreasing profile can be considered as an efficacious Bragg breakwater. Furthermore, this study investigates the energy transfer that occurs during the movement of surface and internal waves across non-periodic oscillatory profiles. As a result, an energy balance relationship is derived, which specifically applies to surface and interface modes. This work has hydrodynamical relevance to wave propagation in coastal regions and to the hydrodynamics of tsunamis in the open ocean, both of which are affected by changes in the bathymetry of the fluid region. [ABSTRACT FROM AUTHOR]

The widespread use of rubble-mound (RM) breakwaters along coasts across the world highlights the importance of understanding their behavior during natural disasters such as tsunamis. The failure of these breakwaters during tsunamis can have far-reaching consequences, potentially causing damage to coastal infrastructure and loss of life. Many breakwaters failed during past tsunamis. Despite this, studies on the behavior of RM breakwaters during tsunamis are minimal. The present study thus attempts to elucidate the behavior of RM breakwater subjected to a tsunami. Furthermore, efforts were made to develop effective countermeasures that can safeguard the breakwater against tsunamis. To the end, a novel technique of using geogrids for reinforcing the RM is proposed. This study could be a pioneering application of geogrids as reinforcing elements in RM breakwaters to mitigate damages from tsunamis. Geogrid layers are provided on both the seaside and harborside to mitigate tsunami-induced damage to the breakwater. In addition, a crown wall (with shear keys) is also introduced to prevent the scouring of the crest and sheet piles from preventing excess seepage through the seabed. Physical model tests, analytical studies and numerical simulations were carried out to assess the performance of the proposed countermeasures by comparing it with the behavior of conventional RM breakwater during the tsunami. The tsunamis can overflow the breakwater, potentially exceeding its design limits. Hence, provision was made in the study for overflow, where the breakwater may overflow by the tsunami. It was observed that excess seepage through the body of the breakwater and the scouring of the crest were significant factors that led to the failure of RM breakwaters under tsunami overflow. A novel reinforced model was proposed to address these issues. This model effectively withstood tsunami-induced damages without significant deformations, demonstrating its potential as a reliable solution. In the past, tsunamis have caused significant damage to several rubble-mound breakwaters, leading to devastating impacts on coastal communities. The 2004 Indian Ocean tsunami and the 2011 Great East Japan tsunami are two well-known examples of the destructive power of tsunamis. A significant number of breakwaters across the globe are of the rubble-mound type, and finding a practical solution to make them resilient against tsunamis could protect many coasts against future tsunamis. This study proposes novel reinforcing techniques to make the rubble-mound breakwater tsunami-resilient. These techniques include adding geogrid layers on either side, providing a crown wall (with shear key) at the top, and inserting two sheet piles into the seabed at either end of the rubble-mound breakwater. Perhaps, this is the first-time geogrids were used on rubble-mound breakwaters to mitigate tsunami-induced damages. The reinforcing elements were chosen for their practicality in the real world. These elements can be practically applied to make existing and future breakwaters tsunami resilient. The study found that the proposed reinforced model, particularly Reinforced model III, remained intact without significant deformation even under a 15-m high tsunami. [ABSTRACT FROM AUTHOR]

New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery. The chaotic layer truncates sandy-silty paleosol, covers Roman settlements and is overlain by fire remains, a thin sandy-silty aeolian unit and ~ 1-m-thick alluvial deposits. Charcoal samples collected at 10 cm below and 4 cm above the catastrophic deposits provide radiocarbon dating that brackets the catastrophic unit between 286 and 370 CE. Other historical investigations on the Roman sites of Neapolis (Nabeul), Hadrumete (Sousse), Thyna (Sfax), Meninx in Girba (Djerba), Wadi Ennouili (Gulf of Gabes), and Sabratha (in Libya) evidenced major damage and abandonment of sites in the fourth century (16, 41, 42, 43, 44). The new identification of catastrophic deposits, offshore-onshore correlations with turbidites and modelling of tsunami waves suggest the relationship with the 21 July 365 tsunamigenic earthquake (Mw ~ 8) of west Crete (Greece) and call for a better estimate of tsunami risk on the Mediterranean coastlines. [ABSTRACT FROM AUTHOR]

Tsunamigenic earthquakes pose considerable risks, both economically and socially, yet earthquake and tsunami hazard assessments are typically conducted separately. Earthquakes associated with unexpected tsunamis, such as the 2018 Mw7.5 strike-slip Sulawesi earthquake, emphasize the need to study the tsunami potential of active submarine faults in different tectonic settings. Here, we investigate physics-based scenarios combining simulations of 3D earthquake dynamic rupture and seismic wave propagation with tsunami generation and propagation. We present time-dependent modeling of one-way linked and 3D fully coupled earthquakes and tsunamis for the ∼ 100 km long Húsavík–Flatey Fault Zone (HFFZ) in North Iceland. Our analysis shows that the HFFZ has the potential to generate sizable tsunamis. The six dynamic rupture models sourcing our tsunami scenarios vary regarding hypocenter location, spatiotemporal evolution, fault slip, and fault structure complexity but coincide with historical earthquake magnitudes. Earthquake dynamic rupture scenarios on a less segmented fault system, particularly with a hypocenter location in the eastern part of the fault system, have a larger potential for local tsunami generation. Here, dynamically evolving large shallow fault slip (∼ 8 m), near-surface rake rotation (± 20 ∘), and significant coseismic vertical displacements of the local bathymetry (± 1 m) facilitate strike-slip faulting tsunami generation. We model tsunami crest to trough differences (total wave heights) of up to ∼ 0.9 m near the town Ólafsfjörður. In contrast, none of our scenarios endanger the town of Akureyri, which is shielded by multiple reflections within the narrow Eyjafjörður bay and by Hrísey island. We compare the modeled one-way linked tsunami waveforms with simulation results using a 3D fully coupled approach. We find good agreement in the tsunami arrival times and location of maximum tsunami heights. While seismic waves result in transient motions of the sea surface and affect the ocean response, they do not appear to contribute to tsunami generation. However, complex source effects arise in the fully coupled simulations, such as tsunami dispersion effects and the complex superposition of seismic and acoustic waves within the shallow continental shelf of North Iceland. We find that the vertical velocity amplitudes of near-source acoustic waves are unexpectedly high – larger than those corresponding to the actual tsunami – which may serve as a rapid indicator of surface dynamic rupture. Our results have important implications for understanding the tsunamigenic potential of strike-slip fault systems worldwide and the coseismic acoustic wave excitation during tsunami generation and may help to inform future tsunami early warning systems. [ABSTRACT FROM AUTHOR]