Extraction of two tsunamis signals generated by earthquakes around the Pacific rim

As one of the ocean sudden natural disasters,the tsunami is not easily to differentiate from the ocean variation in the open ocean due to the tsunami wave amplitude is less than one meter with hundreds of kilometers wavelength. But the wave height will increases up to tens of meters with enormous energy when the tsunami arrives at the coast. It would not only devastate entire cities near coast,but also kill millions of people. It is necessary to forecast and make warning before the tsunami arriving for many countries and regions around the Pacific rim. Two kinds of data were used in this study to extract the signals of 2011 Tohoku tsunami and 2014Iquique tsunami. Wave undulations from DART（ Deep-ocean Assessment and Reporting of Tsunamis） buoys and SLA from altimetry could extract the tsunami signals generated by this two earthquake. The signals of Tohoku tsunami were stronger than that of Iquique tsunami probably due to the 2011 Tohoku tsunami was generated by a magnitude 9. 0 earthquake and the 2014 Iquique tsunami was triggered by a magnitude 8. 2 earthquake.

Long-Term Statistics of Extreme Tsunami Height at Crescent City

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.

Spherical-earth finite element model of coseismic slip distribution during the 2010 Mentawai earthquake

The moment magnitude(MW)7.8 earthquake occurred along the Mentawai seismic region of Sunda Trench on 25 October 2010,which is classified as the tsunami earthquake.The GPS inversion results under the assumption of simple horizontal layered medium show that the slip near the trench is not apparent,which is inconsistent with our understanding of tsunami earthquake.Here,we construct a spherical-earth finite element model(FEM)to investigate the coseismic slip distribution of the 2010 Mentawai earthquake by geometrically combining the subducting plate with a precise subduction interface.The FEM-based coseismic slip distribution shows that there are three major slip patches on the fault interface,one is located on the shallow region and the other two are located on the deeper part of the fault plane.The largest slip patch is located near the trench with the depth less than 10 km,and the maximum amplitude is about 12 m.This significant near-trench slip is consistent with the tsunami earthquake studies.A more realistic domain of FEM is used to change the coseismic slip distribution,thus significantly improving the fitting degree of the data model.These findings suggest that the FEM-derived Green's function is essential to image a more robust and realistic coseismic slip distribution of the large earthquake in the subduction zone.

Deformations of Land,Sea and Gravity Levels by the 2009 Samoa Earthquake

The Samoa Islands were struck by the September 2009 earthquake of Mw 8.1. We study the effect on the land level by means of GPS monitoring and on ocean level by tide-gauge records. This allows us to present a new picture of the interaction of crustal movements, gravitational adjustment and sea level changes. The land level exhibits a co-seismic uplift followed by a post-seismic crustal subsidence. The ocean level records a fall, significantly larger than the uplift and delayed by several months, followed by a significant rise, by far exceeding the crustal subsidence and delayed by several months. This indicates a significant contribution from changes in gravity (geoidal eustasy), besides relative sea level changes due to crustal movements. High amplitude, and high frequency changes in tidal range provide evidence of changes in gravity and geoidal eustasy.

全球海啸相关研究进展综述

With the advancement of the global economy,the coastal region has become heavily developed and densely populated and suffers significant damage potential considering various natural disasters,including tsunamis,as indicated by several catastrophic tsunami disasters in the 21st century.This study reviews the up-to-date tsunami research from two different viewpoints:tsunamis caused by different generation mechanisms and tsunami research applying different research approaches.For the first issue,earthquake-induced,landslide-induced,volcano eruption-induced,and meteorological tsunamis are individually reviewed,and the characteristics of each tsunami research are specified.Regarding the second issue,tsunami research using post-tsunami field surveys,numerical simulations,and laboratory experiments are discussed individually.Research outcomes from each approach are then summarized.With the extending and deepening of the understanding of tsunamis and their inherent physical insights,highly effective and precise tsunami early warning systems and countermeasures are expected for the relevant disaster protection and mitigation efforts in the coastal region.

Disaster Recovery and Reconstruction Following the 2011 Great East Japan Earthquake and Tsunami: A Business Process Management Perspective

The Tohoku Regional Bureau(TRB) of the Ministry of Land, Infrastructure, Transport and Tourism(MLIT) performed various actions in response to the 2011 Great East Japan Earthquake and Tsunami. The total disaster recovery and reconstruction period is expected to last for 10 years, of which the first five years are regarded as the concentrated reconstruction period. As of 2013, a majority of the mega projects that involved restoration actions have been completed, which indicates a more effective rate of completion compared with the MLIT projects performed in normal non-disaster situations. This short article explains the management process of the recovery and reconstruction utilized by the TRB—an interorganizational process—from a business process management(BPM) perspective and creates a simple organization construction diagram of the entire process. The study focused on the transactions and actor roles to identify their strengths. The findings indicate the utilization of different operational procedures in some parts of the process, the importance of liaison role, as well as some obstacles. The lessons learned from this analysis can assist managers and researchers in designing and managing restoration processes for future disasters.

Seismological Research in Indonesia1

Indonesia is situated at the juncture of three major tectonic plates: the Eurasian, the Pacific and the Indo-Australian plates. As a result, many parts of the country are classified as being at a high risk of earthquake and tsunami disasters. In Indonesia, the Bureau of Meteorology and Geophysics (BMG) is the agency responsible for the monitoring of tectonic earthquakes and tsunamis induced by them. For this purpose, BMG operates seismic networks throughout Indonesia. In order to serve better, BMG will have to improve its monitoring system. Many agencies and universities in Indonesia have done research in the field of seismology, including seismotectonics, earthquake hazards, and so on. Joint research has been done with agencies/universities from abroad. Considering the fact that some earthquake prone areas in Indonesia suffer from frequent disasters, a study on earthquake prediction in some areas of interest would contribute to achieving some long-term goals of the Bureau.

Households' Risk Perception and Behavioral Responses to Natech Accidents

This study analyzes data on households' risk perception and protective behavior following a natural disaster triggered technological accident(Natech accident)that occurred at an industrial park in Sendai during the Great East Japan Earthquake and Tsunami, on 11 March2011. The results indicate that some households carried out multiple evacuations and that households' risk perceptions changed throughout the Natech accident evacuation process. Risk perception differed according to household location and demographic characteristics. We also found differences in the protective measures adopted for households in different locations. Specifically, those living closer to the Natech accident tended to evacuate immediately,whereas those living further away tended to shelter in place. Wind direction is discussed as a factor that influences households' risk perception and evacuation response to a Natech accident. The findings of this study advance knowledge of household behavior in response to a Natech accident and can assist emergency managers in developing strategies for better management of evacuation processes.