The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed ...The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed throughout the World Ocean.This event was notable for its unprecedented global impact and the early appearance of tsunami waves at distant coastal stations.So,the first waves at tide gauge stations in Chile and Peru were recorded 4 hours earlier than the arrival time of tsunami waves to the tide gauge after the eruption of Tonga volcano.Two mechanisms are possible for the generation of early tsunami waves:acoustic Lamb waves generated by a volcanic explosion and submarine landslides that occurred on the slopes of the volcano during the preparatory phase of the eruption.In this study,numerical simulation of various pre-eruption landslide scenarios on the slope of Hunga Tonga volcano is carried out in an attempt to explain these early tsunami waves.Under computation the elastoplastic model of landslide was taken into account.Wave characteristics of a tsunami on the coast of Chile and Peru generated by a landslide process on a volcanic slope are obtained.A detailed comparison of virtual tide gauge data with observational ones is used to validate this model.The results obtained can be used to improve early warning systems.展开更多
The eruption of the Anak Krakatau volcano,Indonesia,on 22 December 2018 induced a destructive tsunami(the Sunda Strait tsunami),which was recorded by four nearby tidal gauges.In this study we invert the tsunami record...The eruption of the Anak Krakatau volcano,Indonesia,on 22 December 2018 induced a destructive tsunami(the Sunda Strait tsunami),which was recorded by four nearby tidal gauges.In this study we invert the tsunami records and recover the tsunami generation process.Two tsunami sources are obtained,a static one of instant initial water elevation and a time-dependent one accounting for the continuous evolution of water height.The time-dependent results are found to reproduce the tsunami recordings more satisfactorily.The complete tsunami generation process lasts approximately 9 min and features a two-stage evolution with similar intensity.Each stage lasts about 3.5 min and elevates a water volume of about 0.13 km3.The time,duration and volume of the volcano eruption in general agree with seismic records and geomorphological interpretations.We also test different sizes of the potential source region,which lead to different maximum wave height in the source area,but all the results of time-dependent tsunami sources show the robust feature of two stages of wave generation.Our results imply a time-dependent and complex process of tsunami generation during the volcano eruption.展开更多
Since the disastrous aftermath of the 2004 Sumatra Tsunami(Indonesia)and the 2011 Tohoku Tsunami(Japan),China has made much effort to mitigate tsunami hazards.We briefly reviewed the progress of cataloguing,modeling,e...Since the disastrous aftermath of the 2004 Sumatra Tsunami(Indonesia)and the 2011 Tohoku Tsunami(Japan),China has made much effort to mitigate tsunami hazards.We briefly reviewed the progress of cataloguing,modeling,early warning and hazard analysis for tsunamis in China.Compiling a Chinese tsunami catalogue is a challenge at present due to a large number of inconsistent research results.In China,the numerical models widely used in engineering and related studies are developed by other countries,and the development of a domestic model is being funded by the Chinese government.The tsunami early warning system has been set up and used during the recent tsunami events,such as the Chile earthquake on February 27,2010.展开更多
On April 3,2024,a magnitude Mw 7.4 earthquake struck the city of Hualien,Taiwan,China,causing casualties and immense damage.This earthquake triggered a tsunami,which was recorded by the nearby tide gauges and Deep-Oce...On April 3,2024,a magnitude Mw 7.4 earthquake struck the city of Hualien,Taiwan,China,causing casualties and immense damage.This earthquake triggered a tsunami,which was recorded by the nearby tide gauges and Deep-Ocean Assessment and Reporting of Tsunamis(DART)buoys.These recordings are valuable for evaluating the tsunami source and quantifying the tsunami characteristics.In this study,we conduct tsunami simulations based on three earthquake source models,and analyze their reliability by comparing the computed results with observed waveforms.The evaluated source models are the United States Geological Survey(USGS)finite-fault model,and two uniform slip models using different scaling relations.The tsunami waves generated by each source are simulated with a nonhydrostatic tsunami model,which accounts for the effects of wave dispersion.The computed tsunami arrival times and wave heights are compared to the observed data and show high consistency,indicating that the magnitude and location of the earthquake source are well estimated.Also,the three source models with different rupture area and average slip lead to almost the same tsunami waves at each station,which suggests that earthquake rupture details have limited impact on far-filed tsunami records.It is also found that wave dispersion effects in this event are negligible at most stations.The findings are useful for tsunami warning.For fast warning purposes,it is practically useful to adopt simplified uniform slip models,which are able to predict the tsunami arrival time and wave height relatively well without knowing the earthquake source details.展开更多
The spatial distribution of the world population is uneven,with a density of about 40%living in coastal regions.The trend is expected to continue in both demographic indicators and urban development rate,being many co...The spatial distribution of the world population is uneven,with a density of about 40%living in coastal regions.The trend is expected to continue in both demographic indicators and urban development rate,being many coastal cities in seismic-and tsunami-prone regions and built through informal and unplanned settlements,exposing their population and assets to such hazards.Recent tectonic-triggered events raised awareness of the cascading earthquake and tsunami threat and highlighted the paucity of structural design criteria considering the cumulative effects of both.By being exposed to the ground-motion,the structures’resistance may decrease and become residual/non-existent to support the incoming tsunami,implying an underestimation of the risk.Risk management can benefit from reinforcing the ties between natural hazards and engineering practitioners,linking science and industry,and promoting dialogue between risk analysts and policy-makers.Motivated by the expansion plans of an internationally-sized deep-water port located in a tsunami-prone region,a reflection on the work needed to perform a multi-risk assessment and the challenges yet to overcome is introduced to emphasize the challenge of combining safety requirements with financial and ecologic concerns.A conceptual interdisciplinarybased methodology is proposed to support uncertainty-aware,systematic and informed decisions.展开更多
A criterion for tsunami hazard assessment at the local scale is proposed. It is based on travel times and water level height, calculated by the tsunami numerical model, combined with the existence or not of an easy ev...A criterion for tsunami hazard assessment at the local scale is proposed. It is based on travel times and water level height, calculated by the tsunami numerical model, combined with the existence or not of an easy evacuation path from the shoreline to safely high ground and evaluated by field survey. Furthermore, the 1755 Lisbon Tsunami is considered as the worst case scenario, allowing evaluating the impact of a similar scenario at Figueira da Foz municipality, Portugal. The results show that all the beaches are inundated and should be evacuated within an hour after the earthquake. Since there is safely high ground nearby most areas leading to a local tsunami hazard of＂low＂. However, the presence of unstable sand dunes that has been showing signs of collapsing at the south of Cova and Leirosa allowing the tsunami to penetrate inland, inundating the residential areas. For that reason, the local tsunami hazard is ＂moderate＂. The other area which has ＂moderate＂ classification is Cabedelo, because it does not have any coastal protection from tsunami waves, and does not have easy access to the high ground. The marina and fishing port have ＂very low＂ classification, nevertheless it is recommended that vessels evacuate to art offshore area.展开更多
Under the new regulatory requirements for nuclear power plants in Japan, which were enacted in response to the nuclear accident associated with the Great East Japan Earthquake Tsunami that occurred on 11 March 2011, i...Under the new regulatory requirements for nuclear power plants in Japan, which were enacted in response to the nuclear accident associated with the Great East Japan Earthquake Tsunami that occurred on 11 March 2011, it is a requirement to establish a site-specific ＂standard tsunami＂ based on numerical analysis considering non-seismic factors in addition to general seismic faults. It is necessary to establish a consistent evaluation scheme for estimation of tsunami height induced by submarine landslide, since a standard framework for evaluation has not yet been established even though several models for calculation have been proposed and applied in practice. In this study, we estimated the scale of submarine landslide from a literature survey and showed examples of tsunami height evaluation using multiple schemes. As a result of evaluation of tsunami height using three schemes, the Watts model, the KLS model, and the modified-KLS model, the result obtained by the KLS model was comparatively large for every case.展开更多
Historically, Crescent City is one of the most vulnerable communities impacted by tsunamis along the west coast of the United States, largely attributed to its offshore geography. Trans-ocean tsunamis usually produce ...Historically, Crescent City is one of the most vulnerable communities impacted by tsunamis along the west coast of the United States, largely attributed to its offshore geography. Trans-ocean tsunamis usually produce large wave runup at Crescent Harbor resulting in catastrophic damages, property loss and human death. How to determine the return values of tsunami height using relatively short-term observation data is of great significance to assess the tsunami hazards and improve engineering design along the coast of Crescent City. In the present study, the extreme tsunami heights observed along the coast of Crescent City from 1938 to 2015 are fitted using six different probabilistic distributions, namely, the Gumbel distribution, the Weibull distribution, the maximum entropy distribution, the lognormal distribution, the generalized extreme value distribution and the generalized Pareto distribution. The maximum likelihood method is applied to estimate the parameters of all above distributions. Both Kolmogorov-Smirnov test and root mean square error method are utilized for goodness-of-fit test and the better fitting distribution is selected. Assuming that the occurrence frequency of tsunami in each year follows the Poisson distribution, the Poisson compound extreme value distribution can be used to fit the annual maximum tsunami amplitude, and then the point and interval estimations of return tsunami heights are calculated for structural design. The results show that the Poisson compound extreme value distribution fits tsunami heights very well and is suitable to determine the return tsunami heights for coastal disaster prevention.展开更多
In recent studies, the effects of complex costal topography on tsunami run-up has sparked heated discussion. This study mainly aims at investigating the effects of complex costal topography on the tsunami inundation d...In recent studies, the effects of complex costal topography on tsunami run-up has sparked heated discussion. This study mainly aims at investigating the effects of complex costal topography on the tsunami inundation distance and the effectiveness of sand dunes in dissipating tsunami wave energy. The experiments were carried out in a wave flume to investigate the potential reduction effects of wave run-up by non erodible sand dune like features. The results show that increasing dunes spacing could not significantly affect inundation distance. However, if the height of sand dunes is of the same order of magnitude as the incoming tsunami wave and the gaps between the dunes are large enough, successful tsunami mitigation could also be possible.展开更多
The Sumatra-Andaman arc is an active subduction zone and had generated several destructive Tsunamis in the past.In this paper we have analyzed two historical Tsunamigenic earthquakes from this region. One of the histo...The Sumatra-Andaman arc is an active subduction zone and had generated several destructive Tsunamis in the past.In this paper we have analyzed two historical Tsunamigenic earthquakes from this region. One of the historical earthquake is the earthquake of 26th June 1941 in the North Andaman region,which was one of the strongest in the Andaman Sea and Bay of Bengal of magnitude M_w=7.7.This earthquake had triggered tsunami which affected the east coast of India.The other is the earthquake in Car Nicobar region on 31 st December 1881 of magnitude M_w=7.9. This submarine earthquake beneath the展开更多
This paper presents a local tsunami simulation, including the initial displacement field model of tsunami source and tsunami wave propagation model. We deduced the tsunami wave equation; applied the matching of interi...This paper presents a local tsunami simulation, including the initial displacement field model of tsunami source and tsunami wave propagation model. We deduced the tsunami wave equation; applied the matching of interior and exterior solutions method and water mass method to determine the initial displacement field in different bottom topography. Tsunami wave propagation model was based on the Boussinesq equation. Difference format was based on the ADI method which discretized in alternating direction in the form of implicit scheme. The open boundary of ADI had been revised considering the influence of wave propagation in the equation of motion. The local tsunami mathematical model was used in the simulation of 2011 Japan tsunami, and the results and the observation data match well.展开更多
A study of tsunami events in the East （Japan） Sea using continuous Galerkin finite element model, aiming at reproducing tsunami waves generated by underwater earthquakes in 1983 and 1993 respectively has been perfor...A study of tsunami events in the East （Japan） Sea using continuous Galerkin finite element model, aiming at reproducing tsunami waves generated by underwater earthquakes in 1983 and 1993 respectively has been performed focusing on the geographic extent of a topographic feature in the East （Japan） Sea. Numerical models can be the proper tools to study the combined effects of realistic topography. Subsequently, using the FEM based two-dimensional model we have simulated the smoothed and flattened topographic effects by removal of Yamato Rise and seamounts for the cases of tthe 1983 Central region earthquake tsunami and the 1993 southwestern Hokkaido earthquake tsunami. The results have shown that there will be higher tsunamis along the eastern coasts of Korea in general except some areas, like Sokcho with removal of topographic highs, thus providing complicated bottom topography of the East （Japan） Sea as effective tsunami energy scattering.展开更多
At about 3000 C14-year BP or 1200 cal. yrs BC, the Baltic Sea experienced a mega-tsunami with a wave-height of 10 m or more, and a run-up height of up to 16.5 m. This event had significant geological and archaeologica...At about 3000 C14-year BP or 1200 cal. yrs BC, the Baltic Sea experienced a mega-tsunami with a wave-height of 10 m or more, and a run-up height of up to 16.5 m. This event had significant geological and archaeological effects. We explore the records from the Lake M?laren area in Sweden. The tsunami event is linked to seismic ground shaking and methane venting tectonics at several sites. The triggering factor is proposed to be the Kaali meteor impact in Estonia of the same age. The documentation of a mega-tsunami in the middle of the Bronze Age has wide implications both in geology and in archaeology. The archaeological key sites at Annelund and Apalle are reinterpreted in terms of tsunami wave actions remodelling stratigraphy. By extensive coring, we are able to trace the tsunami effects in both off-shore and on-shore environment. At the time of the event, sea level was at +15 m (due to isostatic uplift). The tsunami wave erosion is traced 13.5 m below sea level. The tsunami run-up over land is traced to +29.5 m to +31.5 m (occasionally even higher), implying a run-up of 14.5 - 16.5 m. In ?ngermanland, the tsunami event was absolutely dated at 1171 varve years BC. Archaeologically, the tsunami event coincides well with the transition between Periods II and III of the South Scandinavian Bronze Age. Period III has traditionally been difficult to identify in the cultural materials of the Lake M<span style="font-family:Verdana;">?</span><span style="font-family:Verdana;">laren region.</span>展开更多
The presented paper exhibits theory of the ＂gravitational＂ waves propagation near the Earth surface and in the ocean. There was determined an expression ＂gravitational＂ wave which was registered by the gravimeters...The presented paper exhibits theory of the ＂gravitational＂ waves propagation near the Earth surface and in the ocean. There was determined an expression ＂gravitational＂ wave which was registered by the gravimeters being placed in several points of the Earth globe. Alteration of gravitational field was accompanied by alteration of the ＂gravitational＂ wave which has the velocity differing from the velocity of seismic waves. The theoretical model was proved by many experiments realized under registration of the underwater earthquake core by tens of gravimeters being placed in the Earth globe different points. The ＂gravitational＂ waves assist to increase the right forecast probability of the beginning tsunami to 50%.展开更多
There is a fairly strict relation between maximum tsunami wave heights and causation earthquake magnitudes. This provides a new tool for estimating the magnitude of past earthquakes from the observed wave heights of r...There is a fairly strict relation between maximum tsunami wave heights and causation earthquake magnitudes. This provides a new tool for estimating the magnitude of past earthquakes from the observed wave heights of related paleo-tsunami events. The method is subjected to a test versus two paleoseismic events with multiple independent estimates of corresponding earthquake magnitude. The agreement to the tsunami wave height conversion is good, confirming very high magnitudes of M 8.5 - 9.0 and M 8.4 - 8.5. Applying the same method to two Late Holocene events of methane venting tectonics indicates a ground shaking of forces equivalent to a M 8.0 earthquake, seriously changing previous long-term crustal hazard assessments.展开更多
The original accounts reporting the 1755 Lisbon Tsunami were compiled, focusing on the descriptions related to the tsunami parameters, damage and fatalities in the affected regions （Atlantic Northeast and Caribbean）...The original accounts reporting the 1755 Lisbon Tsunami were compiled, focusing on the descriptions related to the tsunami parameters, damage and fatalities in the affected regions （Atlantic Northeast and Caribbean）. The accounts show the tsunami reached the southwest municipalities of Portugal in less than 30 minutes after the earthquake, and about one hour later the entire coasts of Portugal, Gulf of Cadiz （Spain） and Morocco were hit by the first tsunami waves. The tsunami took about five hours to reach Ireland and UK, and hit the Caribbean region about 9-10 hours after the earthquake. In addition, significant damage and fatalities were reported in Portugal （Peniche, the Lisbon Metropolitan Area and seven coastal areas in the south）, Spain （Cadiz） and in all Morocco coastline, including Marrakech which is located about 200 km inland. In Ireland, UK and the Caribbean minor damage was observed, and no fatalities were reported.展开更多
This paper presents a review of the Japanese policies for tsunami countermeasures before and after the 2011 off the Pacific coast of Tohoku Earthquake and its consequent tsunami.The current status of tsunami geology u...This paper presents a review of the Japanese policies for tsunami countermeasures before and after the 2011 off the Pacific coast of Tohoku Earthquake and its consequent tsunami.The current status of tsunami geology under the new policies is also discussed.The 2011 event was regarded as an unexpected hazard.Such a large hazard had not been considered for Japanese tsunami countermeasures before,although geological studies have indicated their potential occurrence.Based on lessons learned from the 2011 event,the Japanese government changed policies related to tsunami disaster countermeasures.The salient change is that estimation of the maximum possible earthquake and tsunami along the each coast of Japan is now required.展开更多
The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor de...The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor decisions and inaction,and advances in computing power and data mining call for new scientific approaches.Three fundamental requirements for mitigating impacts of natural hazards are defined.These are:(1)improvement of process-oriented understanding,(2)adequate monitoring and optimal use of data,and(3)generation of advice based on scientific,technical and socio-economic expertise.International leadership/coordination is also important.展开更多
The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact t...The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact the southeast coast of China if tsunamis occur in these areas. In this paper, the horizontal two-dimensional Boussinesq model is used to simulate tsunami generation, propagation, and runnp in a domain with complex geometrical boundaries. The temporary varying bottom boundary condition is adopted to describe the initial tsunami waves motivated by the submarine faults. The Indian Ocean tsunami is simulated by the numerical model as a validation case. The time series of water elevation and runup on the beach are compared with the measured data from field survey. The agreements indicate that the Boussinesq model can be used to simulate tsunamis and predict the waveform and runup. Then, the hypothetical tsunamis in the Okinawa Trench and the Manila Trench are simulated by the numerical model. The arrival time and maximum wave height near coastal cities are predicted by the model. It turns out that the leading depression N-wave occurs when the tsunami propagates in the continental shelf from the Okinawa Trench. The scenarios of the tsunami in the Manila Trench demonstrate significant effects on the coastal area around the South China Sea.展开更多
Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by ...Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor,usually no interaction between them is consid-ered in pure liquid model.In this study,the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami.For model-ing the earthquake,firstly the initial stress field to generate the earthquake is set up,and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault.It is dif-ferent from seismic dislocation theory in which the relative slip on the fault is specified in advance.The modeling results reveal that P,SP and the surface wave can be found at the sea surface besides the tsunami wave.The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes,and its maximum amplitude is 0.55 m,which is 2 times as large as that of the sea floor.Tsunami warning information can be taken from the surface wave on the sea surface,which is much earlier than that obtained from the seismograph stations on land.The tsunami speed on the open sea with 3 km depth is 175.8 m/s,which is a little greater than that pre-dicted by long wave theory,(gh)1/2=171.5 m,and its wavelength and amplitude in average are 32 km and 2 m,respectively.After the tsunami propagates to the continental shelf,its speed and wavelength is reduced,but its amplitude become greater,especially,it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore,respectively.The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/s2 and 16.5 m/s2,respectively,the later is 2.8 times the former,and therefore,sea water is a good shock absorber.The acceleration at the sea shore is about 1/10 as large as at the epicenter.The maximum vertical velocity at the epicenter is 1.4 times that on the fault.The maximum vertical displacement at the fault is less than that at the epicenter.The difference between them is the amplitude of the tsunami at the epicenter.The time of the maximum displacement to occur on the fault is not at the beginning of the fault slipping but retards 23 s.展开更多
基金funded by the Ministry of Science and Higher Education of the Russian Federation(agreement No.075-15-2022-1127 dated July 1,2022).
文摘The paper considers a catastrophic event-the eruption of Hunga Tonga-Hunga Ha’apai volcano on January 15,2022.The process of preparation and eruption of Hunga Tonga volcano generated tsunami waves that were observed throughout the World Ocean.This event was notable for its unprecedented global impact and the early appearance of tsunami waves at distant coastal stations.So,the first waves at tide gauge stations in Chile and Peru were recorded 4 hours earlier than the arrival time of tsunami waves to the tide gauge after the eruption of Tonga volcano.Two mechanisms are possible for the generation of early tsunami waves:acoustic Lamb waves generated by a volcanic explosion and submarine landslides that occurred on the slopes of the volcano during the preparatory phase of the eruption.In this study,numerical simulation of various pre-eruption landslide scenarios on the slope of Hunga Tonga volcano is carried out in an attempt to explain these early tsunami waves.Under computation the elastoplastic model of landslide was taken into account.Wave characteristics of a tsunami on the coast of Chile and Peru generated by a landslide process on a volcanic slope are obtained.A detailed comparison of virtual tide gauge data with observational ones is used to validate this model.The results obtained can be used to improve early warning systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1901602,11632012,41861144024 and 41974017).
文摘The eruption of the Anak Krakatau volcano,Indonesia,on 22 December 2018 induced a destructive tsunami(the Sunda Strait tsunami),which was recorded by four nearby tidal gauges.In this study we invert the tsunami records and recover the tsunami generation process.Two tsunami sources are obtained,a static one of instant initial water elevation and a time-dependent one accounting for the continuous evolution of water height.The time-dependent results are found to reproduce the tsunami recordings more satisfactorily.The complete tsunami generation process lasts approximately 9 min and features a two-stage evolution with similar intensity.Each stage lasts about 3.5 min and elevates a water volume of about 0.13 km3.The time,duration and volume of the volcano eruption in general agree with seismic records and geomorphological interpretations.We also test different sizes of the potential source region,which lead to different maximum wave height in the source area,but all the results of time-dependent tsunami sources show the robust feature of two stages of wave generation.Our results imply a time-dependent and complex process of tsunami generation during the volcano eruption.
基金supported by the National Natural Science Fund No.51278473the Environmental Protection Research Fund for Public Interest No.201209040the northeast Asia(China-Japan-Korea)cooperative research project of earthquake,tsunami and volcano No.ZRH2014-11.
文摘Since the disastrous aftermath of the 2004 Sumatra Tsunami(Indonesia)and the 2011 Tohoku Tsunami(Japan),China has made much effort to mitigate tsunami hazards.We briefly reviewed the progress of cataloguing,modeling,early warning and hazard analysis for tsunamis in China.Compiling a Chinese tsunami catalogue is a challenge at present due to a large number of inconsistent research results.In China,the numerical models widely used in engineering and related studies are developed by other countries,and the development of a domestic model is being funded by the Chinese government.The tsunami early warning system has been set up and used during the recent tsunami events,such as the Chile earthquake on February 27,2010.
基金The National Key R&D Program of China under contract No.2024YFF0506800the National Natural Science Foundation of China under contract No.T2122012.
文摘On April 3,2024,a magnitude Mw 7.4 earthquake struck the city of Hualien,Taiwan,China,causing casualties and immense damage.This earthquake triggered a tsunami,which was recorded by the nearby tide gauges and Deep-Ocean Assessment and Reporting of Tsunamis(DART)buoys.These recordings are valuable for evaluating the tsunami source and quantifying the tsunami characteristics.In this study,we conduct tsunami simulations based on three earthquake source models,and analyze their reliability by comparing the computed results with observed waveforms.The evaluated source models are the United States Geological Survey(USGS)finite-fault model,and two uniform slip models using different scaling relations.The tsunami waves generated by each source are simulated with a nonhydrostatic tsunami model,which accounts for the effects of wave dispersion.The computed tsunami arrival times and wave heights are compared to the observed data and show high consistency,indicating that the magnitude and location of the earthquake source are well estimated.Also,the three source models with different rupture area and average slip lead to almost the same tsunami waves at each station,which suggests that earthquake rupture details have limited impact on far-filed tsunami records.It is also found that wave dispersion effects in this event are negligible at most stations.The findings are useful for tsunami warning.For fast warning purposes,it is practically useful to adopt simplified uniform slip models,which are able to predict the tsunami arrival time and wave height relatively well without knowing the earthquake source details.
基金supported by Fundacao para a Ciencia e Tecnologia,PhD grant no.SFRH/BD/137531/2018,ongoing at Lisbon University,Instituto Superior Tecnico,Civil Engineering Research and Innovation for Sustainability(CERIS)Lopes and Reis are grateful for the Foundation for Science and Technology’s support through funding UIDB/04625/2020 from the research unit CERIS+1 种基金finantial support by FEDER-Fundo Europeu de Desenvolvimento Regional,through COMPETE 2020-Programa Operacional Fatores de Competitividadethe National Funds through FCT-Fundacao para a Ciencia e Tecnologia,projects no.UID/FIS/04650/2019 and no.POCI-01-0145-FEDER-028118.
文摘The spatial distribution of the world population is uneven,with a density of about 40%living in coastal regions.The trend is expected to continue in both demographic indicators and urban development rate,being many coastal cities in seismic-and tsunami-prone regions and built through informal and unplanned settlements,exposing their population and assets to such hazards.Recent tectonic-triggered events raised awareness of the cascading earthquake and tsunami threat and highlighted the paucity of structural design criteria considering the cumulative effects of both.By being exposed to the ground-motion,the structures’resistance may decrease and become residual/non-existent to support the incoming tsunami,implying an underestimation of the risk.Risk management can benefit from reinforcing the ties between natural hazards and engineering practitioners,linking science and industry,and promoting dialogue between risk analysts and policy-makers.Motivated by the expansion plans of an internationally-sized deep-water port located in a tsunami-prone region,a reflection on the work needed to perform a multi-risk assessment and the challenges yet to overcome is introduced to emphasize the challenge of combining safety requirements with financial and ecologic concerns.A conceptual interdisciplinarybased methodology is proposed to support uncertainty-aware,systematic and informed decisions.
文摘A criterion for tsunami hazard assessment at the local scale is proposed. It is based on travel times and water level height, calculated by the tsunami numerical model, combined with the existence or not of an easy evacuation path from the shoreline to safely high ground and evaluated by field survey. Furthermore, the 1755 Lisbon Tsunami is considered as the worst case scenario, allowing evaluating the impact of a similar scenario at Figueira da Foz municipality, Portugal. The results show that all the beaches are inundated and should be evacuated within an hour after the earthquake. Since there is safely high ground nearby most areas leading to a local tsunami hazard of＂low＂. However, the presence of unstable sand dunes that has been showing signs of collapsing at the south of Cova and Leirosa allowing the tsunami to penetrate inland, inundating the residential areas. For that reason, the local tsunami hazard is ＂moderate＂. The other area which has ＂moderate＂ classification is Cabedelo, because it does not have any coastal protection from tsunami waves, and does not have easy access to the high ground. The marina and fishing port have ＂very low＂ classification, nevertheless it is recommended that vessels evacuate to art offshore area.
文摘Under the new regulatory requirements for nuclear power plants in Japan, which were enacted in response to the nuclear accident associated with the Great East Japan Earthquake Tsunami that occurred on 11 March 2011, it is a requirement to establish a site-specific ＂standard tsunami＂ based on numerical analysis considering non-seismic factors in addition to general seismic faults. It is necessary to establish a consistent evaluation scheme for estimation of tsunami height induced by submarine landslide, since a standard framework for evaluation has not yet been established even though several models for calculation have been proposed and applied in practice. In this study, we estimated the scale of submarine landslide from a literature survey and showed examples of tsunami height evaluation using multiple schemes. As a result of evaluation of tsunami height using three schemes, the Watts model, the KLS model, and the modified-KLS model, the result obtained by the KLS model was comparatively large for every case.
基金supported by the National Natural Science Foundation of China (51279186, 51479183, 51509227)the National Key Research and Development Program (2016YFC0802301)+1 种基金the National Program on Key Basic Research Project (2011CB013704)the Shandong Province Natural Science Foundation, China (ZR2014EEQ030)
文摘Historically, Crescent City is one of the most vulnerable communities impacted by tsunamis along the west coast of the United States, largely attributed to its offshore geography. Trans-ocean tsunamis usually produce large wave runup at Crescent Harbor resulting in catastrophic damages, property loss and human death. How to determine the return values of tsunami height using relatively short-term observation data is of great significance to assess the tsunami hazards and improve engineering design along the coast of Crescent City. In the present study, the extreme tsunami heights observed along the coast of Crescent City from 1938 to 2015 are fitted using six different probabilistic distributions, namely, the Gumbel distribution, the Weibull distribution, the maximum entropy distribution, the lognormal distribution, the generalized extreme value distribution and the generalized Pareto distribution. The maximum likelihood method is applied to estimate the parameters of all above distributions. Both Kolmogorov-Smirnov test and root mean square error method are utilized for goodness-of-fit test and the better fitting distribution is selected. Assuming that the occurrence frequency of tsunami in each year follows the Poisson distribution, the Poisson compound extreme value distribution can be used to fit the annual maximum tsunami amplitude, and then the point and interval estimations of return tsunami heights are calculated for structural design. The results show that the Poisson compound extreme value distribution fits tsunami heights very well and is suitable to determine the return tsunami heights for coastal disaster prevention.
文摘In recent studies, the effects of complex costal topography on tsunami run-up has sparked heated discussion. This study mainly aims at investigating the effects of complex costal topography on the tsunami inundation distance and the effectiveness of sand dunes in dissipating tsunami wave energy. The experiments were carried out in a wave flume to investigate the potential reduction effects of wave run-up by non erodible sand dune like features. The results show that increasing dunes spacing could not significantly affect inundation distance. However, if the height of sand dunes is of the same order of magnitude as the incoming tsunami wave and the gaps between the dunes are large enough, successful tsunami mitigation could also be possible.
文摘The Sumatra-Andaman arc is an active subduction zone and had generated several destructive Tsunamis in the past.In this paper we have analyzed two historical Tsunamigenic earthquakes from this region. One of the historical earthquake is the earthquake of 26th June 1941 in the North Andaman region,which was one of the strongest in the Andaman Sea and Bay of Bengal of magnitude M_w=7.7.This earthquake had triggered tsunami which affected the east coast of India.The other is the earthquake in Car Nicobar region on 31 st December 1881 of magnitude M_w=7.9. This submarine earthquake beneath the
基金The National Natural Science Foundation of China under contract No.51079095the Science Fund for Creative Research Groups of the National Natural Science Foundation of China under contract No.51021004
文摘This paper presents a local tsunami simulation, including the initial displacement field model of tsunami source and tsunami wave propagation model. We deduced the tsunami wave equation; applied the matching of interior and exterior solutions method and water mass method to determine the initial displacement field in different bottom topography. Tsunami wave propagation model was based on the Boussinesq equation. Difference format was based on the ADI method which discretized in alternating direction in the form of implicit scheme. The open boundary of ADI had been revised considering the influence of wave propagation in the equation of motion. The local tsunami mathematical model was used in the simulation of 2011 Japan tsunami, and the results and the observation data match well.
基金The work was financially supported by the Korean Ministry of Land,Transport and Maritime AffairsINTAS(Grant No.06-1000013-9236)
文摘A study of tsunami events in the East （Japan） Sea using continuous Galerkin finite element model, aiming at reproducing tsunami waves generated by underwater earthquakes in 1983 and 1993 respectively has been performed focusing on the geographic extent of a topographic feature in the East （Japan） Sea. Numerical models can be the proper tools to study the combined effects of realistic topography. Subsequently, using the FEM based two-dimensional model we have simulated the smoothed and flattened topographic effects by removal of Yamato Rise and seamounts for the cases of tthe 1983 Central region earthquake tsunami and the 1993 southwestern Hokkaido earthquake tsunami. The results have shown that there will be higher tsunamis along the eastern coasts of Korea in general except some areas, like Sokcho with removal of topographic highs, thus providing complicated bottom topography of the East （Japan） Sea as effective tsunami energy scattering.
文摘At about 3000 C14-year BP or 1200 cal. yrs BC, the Baltic Sea experienced a mega-tsunami with a wave-height of 10 m or more, and a run-up height of up to 16.5 m. This event had significant geological and archaeological effects. We explore the records from the Lake M?laren area in Sweden. The tsunami event is linked to seismic ground shaking and methane venting tectonics at several sites. The triggering factor is proposed to be the Kaali meteor impact in Estonia of the same age. The documentation of a mega-tsunami in the middle of the Bronze Age has wide implications both in geology and in archaeology. The archaeological key sites at Annelund and Apalle are reinterpreted in terms of tsunami wave actions remodelling stratigraphy. By extensive coring, we are able to trace the tsunami effects in both off-shore and on-shore environment. At the time of the event, sea level was at +15 m (due to isostatic uplift). The tsunami wave erosion is traced 13.5 m below sea level. The tsunami run-up over land is traced to +29.5 m to +31.5 m (occasionally even higher), implying a run-up of 14.5 - 16.5 m. In ?ngermanland, the tsunami event was absolutely dated at 1171 varve years BC. Archaeologically, the tsunami event coincides well with the transition between Periods II and III of the South Scandinavian Bronze Age. Period III has traditionally been difficult to identify in the cultural materials of the Lake M<span style="font-family:Verdana;">?</span><span style="font-family:Verdana;">laren region.</span>
文摘The presented paper exhibits theory of the ＂gravitational＂ waves propagation near the Earth surface and in the ocean. There was determined an expression ＂gravitational＂ wave which was registered by the gravimeters being placed in several points of the Earth globe. Alteration of gravitational field was accompanied by alteration of the ＂gravitational＂ wave which has the velocity differing from the velocity of seismic waves. The theoretical model was proved by many experiments realized under registration of the underwater earthquake core by tens of gravimeters being placed in the Earth globe different points. The ＂gravitational＂ waves assist to increase the right forecast probability of the beginning tsunami to 50%.
文摘There is a fairly strict relation between maximum tsunami wave heights and causation earthquake magnitudes. This provides a new tool for estimating the magnitude of past earthquakes from the observed wave heights of related paleo-tsunami events. The method is subjected to a test versus two paleoseismic events with multiple independent estimates of corresponding earthquake magnitude. The agreement to the tsunami wave height conversion is good, confirming very high magnitudes of M 8.5 - 9.0 and M 8.4 - 8.5. Applying the same method to two Late Holocene events of methane venting tectonics indicates a ground shaking of forces equivalent to a M 8.0 earthquake, seriously changing previous long-term crustal hazard assessments.
文摘The original accounts reporting the 1755 Lisbon Tsunami were compiled, focusing on the descriptions related to the tsunami parameters, damage and fatalities in the affected regions （Atlantic Northeast and Caribbean）. The accounts show the tsunami reached the southwest municipalities of Portugal in less than 30 minutes after the earthquake, and about one hour later the entire coasts of Portugal, Gulf of Cadiz （Spain） and Morocco were hit by the first tsunami waves. The tsunami took about five hours to reach Ireland and UK, and hit the Caribbean region about 9-10 hours after the earthquake. In addition, significant damage and fatalities were reported in Portugal （Peniche, the Lisbon Metropolitan Area and seven coastal areas in the south）, Spain （Cadiz） and in all Morocco coastline, including Marrakech which is located about 200 km inland. In Ireland, UK and the Caribbean minor damage was observed, and no fatalities were reported.
基金supported by the Japan Nuclear Energy Safety(currently Nuclear Regulation Authority)by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science(K.Goto,26302007).
文摘This paper presents a review of the Japanese policies for tsunami countermeasures before and after the 2011 off the Pacific coast of Tohoku Earthquake and its consequent tsunami.The current status of tsunami geology under the new policies is also discussed.The 2011 event was regarded as an unexpected hazard.Such a large hazard had not been considered for Japanese tsunami countermeasures before,although geological studies have indicated their potential occurrence.Based on lessons learned from the 2011 event,the Japanese government changed policies related to tsunami disaster countermeasures.The salient change is that estimation of the maximum possible earthquake and tsunami along the each coast of Japan is now required.
文摘The International Union of Geological Sciences(IUGS)is evaluating whether there are additional geoscientific activities that would be beneficial in helping mitigate the impacts of tsunami.Public concerns about poor decisions and inaction,and advances in computing power and data mining call for new scientific approaches.Three fundamental requirements for mitigating impacts of natural hazards are defined.These are:(1)improvement of process-oriented understanding,(2)adequate monitoring and optimal use of data,and(3)generation of advice based on scientific,technical and socio-economic expertise.International leadership/coordination is also important.
基金financially supported by the National Natural Science Foundation of China(Grant No.11202130)the National Science Foundation of Shanghai Municipality(Grant No.11ZR1418200)the Doctoral Program Foundation of Higher Education(Grant No.20060248046)
文摘The Okinawa Trench in the East China Sea and the Manila Trench in the South China Sea are considered to be the regions with high risk of potential tsunamis induced by submarine earthquakes. Tsunami waves will impact the southeast coast of China if tsunamis occur in these areas. In this paper, the horizontal two-dimensional Boussinesq model is used to simulate tsunami generation, propagation, and runnp in a domain with complex geometrical boundaries. The temporary varying bottom boundary condition is adopted to describe the initial tsunami waves motivated by the submarine faults. The Indian Ocean tsunami is simulated by the numerical model as a validation case. The time series of water elevation and runup on the beach are compared with the measured data from field survey. The agreements indicate that the Boussinesq model can be used to simulate tsunamis and predict the waveform and runup. Then, the hypothetical tsunamis in the Okinawa Trench and the Manila Trench are simulated by the numerical model. The arrival time and maximum wave height near coastal cities are predicted by the model. It turns out that the leading depression N-wave occurs when the tsunami propagates in the continental shelf from the Okinawa Trench. The scenarios of the tsunami in the Manila Trench demonstrate significant effects on the coastal area around the South China Sea.
基金National Natural Science Foundation of China (40521002 and 40474013).
文摘Tsunami induced by earthquake is an interaction problem between liquid and solid.Shallow-water wave equation is often used to modeling the tsunami,and the boundary or initial condition of the problem is determined by the displacement or velocity field from the earthquake under sea floor,usually no interaction between them is consid-ered in pure liquid model.In this study,the potential flow theory and the finite element method with the interaction between liquid and solid are employed to model the dynamic processes of the earthquake and tsunami.For model-ing the earthquake,firstly the initial stress field to generate the earthquake is set up,and then the occurrence of the earthquake is simulated by suddenly reducing the elastic material parameters inside the earthquake fault.It is dif-ferent from seismic dislocation theory in which the relative slip on the fault is specified in advance.The modeling results reveal that P,SP and the surface wave can be found at the sea surface besides the tsunami wave.The surface wave arrives at the distance of 600 km from the epicenter earlier than the tsunami 48 minutes,and its maximum amplitude is 0.55 m,which is 2 times as large as that of the sea floor.Tsunami warning information can be taken from the surface wave on the sea surface,which is much earlier than that obtained from the seismograph stations on land.The tsunami speed on the open sea with 3 km depth is 175.8 m/s,which is a little greater than that pre-dicted by long wave theory,(gh)1/2=171.5 m,and its wavelength and amplitude in average are 32 km and 2 m,respectively.After the tsunami propagates to the continental shelf,its speed and wavelength is reduced,but its amplitude become greater,especially,it can elevate up to 10 m and run 55 m forward in vertical and horizontal directions at sea shore,respectively.The maximum vertical accelerations at the epicenter on the sea surface and on the earthquake fault are 5.9 m/s2 and 16.5 m/s2,respectively,the later is 2.8 times the former,and therefore,sea water is a good shock absorber.The acceleration at the sea shore is about 1/10 as large as at the epicenter.The maximum vertical velocity at the epicenter is 1.4 times that on the fault.The maximum vertical displacement at the fault is less than that at the epicenter.The difference between them is the amplitude of the tsunami at the epicenter.The time of the maximum displacement to occur on the fault is not at the beginning of the fault slipping but retards 23 s.
