Earthquake engineering research and development have received much attention since the first half of the twentieth century. This valuable research presented a huge step forward in understanding earthquake hazard mitig...Earthquake engineering research and development have received much attention since the first half of the twentieth century. This valuable research presented a huge step forward in understanding earthquake hazard mitigation,which resulted in appreciable reduction of the effects of past earthquakes. Nevertheless,the 2011 Tohoku earthquake and the subsequent tsunami resulted in major damage. This paper presents the timeline of earthquake mitigation and recovery,as seen by the authors. Possible research directions where the authors think that many open questions still remain are identified. These are primarily based on the important lessons learned from the 2011 Tohoku earthquake.展开更多
Teleseismic and GPS data were jointly inverted for the rupture process of the 2011 Tohoku earthquake. The inversion results show that it is a bilateral rupture event with an average rupture velocity less than 2.0 km/s...Teleseismic and GPS data were jointly inverted for the rupture process of the 2011 Tohoku earthquake. The inversion results show that it is a bilateral rupture event with an average rupture velocity less than 2.0 km/s along the fault strike direction. The source rupture process consists of three sub-events, the first occurred near the hypocenter and the rest two ruptured along the updip direction and broke the sea bed, causing a maximum slip of about 30 m. The large-scale sea bed breakage may account for the tremendous tsunami disaster which resulted in most of the death and missing in this mega earthquake.展开更多
The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic o...The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic offsets at the offshore epicentre of the Mw 9.0 event remain unanswered and being investigated along with their near and far field limiting distances from the epicentre. Accordingly, offset measurements from 60 continuously operating IGS and GEONET GNSS stations were radially classified from the epicentre and interpreted with analytical models to find their linear offset decay rates. Co-and post-seismic static positional anomaly offsets of sixty days show almost all near field stations had strong or appreciable eastward or south eastward static shifts. Near stations(<250 km) showed both kinematic and static offsets. GEONET station ’0175’ showed maximum resultant static offset of-4.5 m, which diminishes approximately 1-2 cm at far sites like SMST and AIRA. Characteristic decay duration(’b’) of the mean kinematic co-seismic shift(’a’)of near field stations was 17.28 s during earthquake hours with an EW component shift >1.5 m. Spatial models of projected N-S static and kinematic offsets show their asymmetrical distributions around the epicentre with maximum model offset of-1.84 m displaced towards south at-45 km north of the epicentre. The Tohoku-Oki earthquake produced a resultant kinematic offset of-10.2 m towards East at its offshore epicentre;while the estimated near field static offset is ~9.82 m. However, both estimates are bigger than double the resultant offset measured value(~4.3 m) in the Japanese mainland using GPS. The difference in the kinematic and static near field offsets highlight that the near surface had elastic or in-elastic kinematic strain dissipation as against the lithospheric level viscoelastic static response, which resulted rapid kinematic strain release(1.12 cm/km)within the limiting radius of ~220 km from the Tohoku-Oki epicentre.展开更多
On March 11,2011, a M_W9.0 earthquake occurred in the Japan Trench, causing tremendous casualties,and attracting extensive concern. Based on the results of related research,this paper analyzes the observations,phenome...On March 11,2011, a M_W9.0 earthquake occurred in the Japan Trench, causing tremendous casualties,and attracting extensive concern. Based on the results of related research,this paper analyzes the observations,phenomena and understandings of the earthquake from varied aspects,and obtains four main conclusions.(1) The earthquake,occurring in the subduction zone in the Japan Trench located in the northwest boundary of the pacific plate has two zones of concentrated coseismic slip at different depths,and the slip in the deep zone is relatively small. Though there have been many M7. 0 historical earthquakes,slips in the shallow zone are large,but there have been few historical strong earthquakes.(2) Constrained by GPS data,the study of fault movement shows that fault movement in the Japan Trench has a background of widely distributed stability and locking( the locking zone is equivalent that of coseismic rupture zone). Perturbation occurred after the 2008 M8. 0 Hokkaido earthquake,several M7. 0 events had after slips larger than the coseismic slip,and two obvious slow slip events were recorded in 2008 and2011. Eventually,the March 9,2011 M7. 0 foreshock and the March 11,2011 M_W9.0 mainshock occurred. The pre-earthquake changing of the fault movement in the Japan Trench is quite clear.(3) Traditional precursory observation show no obvious anomaly,possibly due to monitoring reason. Anomaly before earthquake consists of high stress state in focal zone reflected by some seismic activity parameters,short period anomaly in regional ground motion,etc.(4) The analysis of physical property in focal zone aroused more scientific issues,for example,is there obvious difference between physical property in focal zone and its vicinity? Does frictional property of fault determine seismogenic ability and rupture process? Whether pre-earthquake fault movement include pre-slips? Could deep fluid affect fault movement in focal zone? Experience is the best teacher,and authors hope this paper could be a modest spur to induce others in basic research in earthquake forecast and prediction.展开更多
The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions ca...The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions caused severe damage in wide areas, particularly many towns along the Pacific coast. So far, gravity change caused by such a great earthquake has been reported for the 1964 Alaska and the 2010 Maule events. However, the spatial-temporal resolution of the gravity data for these cases is insufficient to depict a co-seismic gravity field variation in a spatial scale of a plate subduction zone. Here, we report an unequivocal co-seismic gravity change over the Japanese Island, obtained from a hybrid gravity observation(combined absolute and relative gravity measurements). The time interval of the observation before and after the earthquake is within 1 year at almost all the observed sites, including 13 absolute and 16 relative measurement sites, which deduced tectonic and environmental contributions to the gravity change. The observed gravity agrees well with the result calculated by a dislocation theory based on a self-gravitating and layered spherical earth model. In this computation, a co-seismic slip distribution is determined by an inversion of Global Positioning System(GPS) data. Of particular interest is that the observed gravity change in some area is negative where a remarkable subsidence is observed by GPS, which can not be explained by simple vertical movement of the crust. This indicated that the mass redistribution in the underground affects the gravity change. This result supports the result that Gravity Recovery and Climate Experiment(GRACE) satellites detected a crustal dilatation due to the 2004 Sumatra earthquake by the terrestrial observation with a higher spatial and temporal resolution.展开更多
This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province, China, which has been digitally renovated, and probes into the cause of the major differences in the ...This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province, China, which has been digitally renovated, and probes into the cause of the major differences in the earthquake reflecting abilities of well holes at different measurement points. This is achieved through the analysis of the co-seismic responses to the Wenchuan (2008; Ms8.0, China) and Tohoku (2011; Ms9.0, Japan) earthquakes. We found that the co-seismic response of water level from regional well holes in Jiangsu Province was stronger than that of water temperature. The water-level co-seismic response follows a consistent law and is closely related to the earthquake magnitude. The co-seismic response of water temperature strongly varied among well points, and was more often manifested as a slow restorative change. The co-seismic responses also varied based on tectonic elements. The response in central and northern Jiangsu was weaker than that of southern Jiangsu, possibly due to the thicker loess cover layer in central Jiangsu which makes it less effective at capturing the micro-changes of stress-strain states relative to the hilly land in the south. The more complicated geological structure in southern Jiangsu makes it contribute to greater changes in the state of underground water after a minor disturbance.展开更多
On March 11, 2011, a major earthquake and tsunami occurred in Japan, mainly affecting the Tohoku region and causing a meltdown at the Fukushima Daiichi nuclear power plant. This disaster not only caused great damage t...On March 11, 2011, a major earthquake and tsunami occurred in Japan, mainly affecting the Tohoku region and causing a meltdown at the Fukushima Daiichi nuclear power plant. This disaster not only caused great damage to the affected areas but also had a serious impact on Japanese politics, economy, and society in general. The art field was no exception;Japanese artists began to consider “What art can do?” after the disaster and this question began to be a new theme of Japanese contemporary art. Artists began to find ways to engage with the affected communities, dealing directly with social problems and political issues.展开更多
文摘Earthquake engineering research and development have received much attention since the first half of the twentieth century. This valuable research presented a huge step forward in understanding earthquake hazard mitigation,which resulted in appreciable reduction of the effects of past earthquakes. Nevertheless,the 2011 Tohoku earthquake and the subsequent tsunami resulted in major damage. This paper presents the timeline of earthquake mitigation and recovery,as seen by the authors. Possible research directions where the authors think that many open questions still remain are identified. These are primarily based on the important lessons learned from the 2011 Tohoku earthquake.
基金financially supported by the National Natural Science Foundation of China (Nos. 90915012 and 41090291)the Research Project in Earthquake Science, CEA (No.201108002)
文摘Teleseismic and GPS data were jointly inverted for the rupture process of the 2011 Tohoku earthquake. The inversion results show that it is a bilateral rupture event with an average rupture velocity less than 2.0 km/s along the fault strike direction. The source rupture process consists of three sub-events, the first occurred near the hypocenter and the rest two ruptured along the updip direction and broke the sea bed, causing a maximum slip of about 30 m. The large-scale sea bed breakage may account for the tremendous tsunami disaster which resulted in most of the death and missing in this mega earthquake.
文摘The Mw 9.0 Tohoku-Oki earthquake that hit the mainland Japan on 11 th March, 2011 had resulted a devastating Tsunami due to an active thrusting between the Pacific and the North American Plates. Static and kinematic offsets at the offshore epicentre of the Mw 9.0 event remain unanswered and being investigated along with their near and far field limiting distances from the epicentre. Accordingly, offset measurements from 60 continuously operating IGS and GEONET GNSS stations were radially classified from the epicentre and interpreted with analytical models to find their linear offset decay rates. Co-and post-seismic static positional anomaly offsets of sixty days show almost all near field stations had strong or appreciable eastward or south eastward static shifts. Near stations(<250 km) showed both kinematic and static offsets. GEONET station ’0175’ showed maximum resultant static offset of-4.5 m, which diminishes approximately 1-2 cm at far sites like SMST and AIRA. Characteristic decay duration(’b’) of the mean kinematic co-seismic shift(’a’)of near field stations was 17.28 s during earthquake hours with an EW component shift >1.5 m. Spatial models of projected N-S static and kinematic offsets show their asymmetrical distributions around the epicentre with maximum model offset of-1.84 m displaced towards south at-45 km north of the epicentre. The Tohoku-Oki earthquake produced a resultant kinematic offset of-10.2 m towards East at its offshore epicentre;while the estimated near field static offset is ~9.82 m. However, both estimates are bigger than double the resultant offset measured value(~4.3 m) in the Japanese mainland using GPS. The difference in the kinematic and static near field offsets highlight that the near surface had elastic or in-elastic kinematic strain dissipation as against the lithospheric level viscoelastic static response, which resulted rapid kinematic strain release(1.12 cm/km)within the limiting radius of ~220 km from the Tohoku-Oki epicentre.
基金sponsored by the Special Fund for Earthquake Scientific Research(201408019)the Basic Scientific Research Program,Institute of Earth Science,CEA(2016IE0301)
文摘On March 11,2011, a M_W9.0 earthquake occurred in the Japan Trench, causing tremendous casualties,and attracting extensive concern. Based on the results of related research,this paper analyzes the observations,phenomena and understandings of the earthquake from varied aspects,and obtains four main conclusions.(1) The earthquake,occurring in the subduction zone in the Japan Trench located in the northwest boundary of the pacific plate has two zones of concentrated coseismic slip at different depths,and the slip in the deep zone is relatively small. Though there have been many M7. 0 historical earthquakes,slips in the shallow zone are large,but there have been few historical strong earthquakes.(2) Constrained by GPS data,the study of fault movement shows that fault movement in the Japan Trench has a background of widely distributed stability and locking( the locking zone is equivalent that of coseismic rupture zone). Perturbation occurred after the 2008 M8. 0 Hokkaido earthquake,several M7. 0 events had after slips larger than the coseismic slip,and two obvious slow slip events were recorded in 2008 and2011. Eventually,the March 9,2011 M7. 0 foreshock and the March 11,2011 M_W9.0 mainshock occurred. The pre-earthquake changing of the fault movement in the Japan Trench is quite clear.(3) Traditional precursory observation show no obvious anomaly,possibly due to monitoring reason. Anomaly before earthquake consists of high stress state in focal zone reflected by some seismic activity parameters,short period anomaly in regional ground motion,etc.(4) The analysis of physical property in focal zone aroused more scientific issues,for example,is there obvious difference between physical property in focal zone and its vicinity? Does frictional property of fault determine seismogenic ability and rupture process? Whether pre-earthquake fault movement include pre-slips? Could deep fluid affect fault movement in focal zone? Experience is the best teacher,and authors hope this paper could be a modest spur to induce others in basic research in earthquake forecast and prediction.
基金supported by the Research Fund Program of Institute of Seismology, Chinese Earthquake Administration (IS201226045)the Open Research Fund Program of the State Key Laboratory of Geodesy and Earth's Dynamics (SKLGED2013-3-7-E)the National Natural Science Foundation of China (41404065)
文摘The greatest earthquake in the modern history of Japan and probably the fourth greatest in the last 100 years in the world occurred on March 11, 2011 off the Pacific coast of Tohoku.Large tsunami and ground motions caused severe damage in wide areas, particularly many towns along the Pacific coast. So far, gravity change caused by such a great earthquake has been reported for the 1964 Alaska and the 2010 Maule events. However, the spatial-temporal resolution of the gravity data for these cases is insufficient to depict a co-seismic gravity field variation in a spatial scale of a plate subduction zone. Here, we report an unequivocal co-seismic gravity change over the Japanese Island, obtained from a hybrid gravity observation(combined absolute and relative gravity measurements). The time interval of the observation before and after the earthquake is within 1 year at almost all the observed sites, including 13 absolute and 16 relative measurement sites, which deduced tectonic and environmental contributions to the gravity change. The observed gravity agrees well with the result calculated by a dislocation theory based on a self-gravitating and layered spherical earth model. In this computation, a co-seismic slip distribution is determined by an inversion of Global Positioning System(GPS) data. Of particular interest is that the observed gravity change in some area is negative where a remarkable subsidence is observed by GPS, which can not be explained by simple vertical movement of the crust. This indicated that the mass redistribution in the underground affects the gravity change. This result supports the result that Gravity Recovery and Climate Experiment(GRACE) satellites detected a crustal dilatation due to the 2004 Sumatra earthquake by the terrestrial observation with a higher spatial and temporal resolution.
基金supported by the Scientific and Technological Support Project of Jiangsu Province (No.BS2007084)Seismic Technology Spark Project (No.XH12020)
文摘This thesis discusses the earthquake reflecting ability of the observation well pattern system of Jiangsu Province, China, which has been digitally renovated, and probes into the cause of the major differences in the earthquake reflecting abilities of well holes at different measurement points. This is achieved through the analysis of the co-seismic responses to the Wenchuan (2008; Ms8.0, China) and Tohoku (2011; Ms9.0, Japan) earthquakes. We found that the co-seismic response of water level from regional well holes in Jiangsu Province was stronger than that of water temperature. The water-level co-seismic response follows a consistent law and is closely related to the earthquake magnitude. The co-seismic response of water temperature strongly varied among well points, and was more often manifested as a slow restorative change. The co-seismic responses also varied based on tectonic elements. The response in central and northern Jiangsu was weaker than that of southern Jiangsu, possibly due to the thicker loess cover layer in central Jiangsu which makes it less effective at capturing the micro-changes of stress-strain states relative to the hilly land in the south. The more complicated geological structure in southern Jiangsu makes it contribute to greater changes in the state of underground water after a minor disturbance.
文摘On March 11, 2011, a major earthquake and tsunami occurred in Japan, mainly affecting the Tohoku region and causing a meltdown at the Fukushima Daiichi nuclear power plant. This disaster not only caused great damage to the affected areas but also had a serious impact on Japanese politics, economy, and society in general. The art field was no exception;Japanese artists began to consider “What art can do?” after the disaster and this question began to be a new theme of Japanese contemporary art. Artists began to find ways to engage with the affected communities, dealing directly with social problems and political issues.
