scholarly journals An Overview of Source Models from Strong Motion Records of the 2011 Tohoku Earthquake

2016 ◽  
Vol 16 (4) ◽  
pp. 4_12-4_21
Author(s):  
Hiroe MIYAKE ◽  
Kimiyuki ASANO ◽  
Kazuki KOKETSU ◽  
Tomotaka IWATA
Keyword(s):  
Strong Motion ◽  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Strong Motion Records ◽  
Source Models

Review: Source Models of the 2011 Tohoku Earthquake and Long-Term Forecast of Large Earthquakes

2014 ◽  
Vol 9 (3) ◽  
pp. 272-280 ◽  
Author(s):  
Kenji Satake ◽  
◽  
Yushiro Fujii ◽  
Keyword(s):  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
Tsunami Source ◽  
The 2011 Tohoku Earthquake ◽  
Term Forecast ◽  
Trench Axis ◽  
Source Models ◽  
Plate Coupling ◽  
Large Earthquakes

Numerous source models of the 2011 Tohoku earthquake have been proposed based on seismic, geodetic and tsunami data. Common features include a seismic moment of ∼ 4×1022 Nm, a duration of up to ∼ 160 s, and the largest slip of about 50 m east of the epicenter. Exact locations of this largest slip differ with the model, but all show considerable slip near the trench axis where plate coupling was considered to be weak and also at deeper part where M∼7 earthquakes repeatedly occurred at average 37-year intervals. The long-term forecast of large earthquakes made by the Earthquake Research Committee was based on earthquakes occurring in the last few centuries and did not consider such a giant earthquake. Among the several issues remaining unsolved is the tsunami source model. Coastal tsunami height distribution requires a tsunami source delayed by a few minutes and extending north of the epicenter, but seismic data do not indicate such a delayed rupture and there is no clear evidence of additional sources such as submarine landslides along the trench axis. Long-term forecast of giant earthquakes must incorporate non-characteristic models such as earthquake occurrence supercycles, assessments of maximum earthquake size independent of past data, and plate coupling based on marine geodetic data. To assess ground shaking and tsunami in presumed M∼9 earthquakes, characterization and scaling relation fromglobal earthquakes must be used.

Strong Motion Records of the 2011 Tohoku Earthquake and its Attenuation Characteristics

2012 ◽  
Vol 7 (6) ◽  
pp. 693-700 ◽  
Author(s):  
Saburoh Midorikawa ◽  
◽  
Hiroyuki Miura ◽  
Tomohiro Atsumi
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
Distribution Model ◽  
Motion Generation ◽  
The 2011 Tohoku Earthquake ◽  
Strong Motion Records ◽  
Attenuation Relationships ◽  
Shortest Distance ◽  
Definition Of

Many strong motion records were obtained during the 2011 Off the Pacific Coast of Tohoku earthquake owing to the implementation of dense strong motion observation in Japan. The earthquake provides an opportunity to examine the characteristics of strong ground motion from a gigantic earthquake. Attenuations of peak acceleration and velocity are examined by comparing them to curves from existing attenuation relationships. When the shortest distance from the fault plane of the slip distribution model is used, curves for Mw8.0 to 8.3 give the smallest deviation from data, suggesting the saturation of ground motion intensity at large magnitudes. When the shortest distance from the strong motion generation areas is used, however, the scattering of data becomes smaller and the curve for Mw9.0 fits acceleration data. Results thus change with the definition of distance. This suggests that a consideration of the rupture heterogeneity is important in strong motion prediction for gigantic earthquakes.

Seismic Hazard Assessment for Japan: Reconsiderations After the 2011 Tohoku Earthquake

2013 ◽  
Vol 8 (5) ◽  
pp. 848-860 ◽  
Author(s):  
Hiroyuki Fujiwara ◽  
◽  
Nobuyuki Morikawa ◽  
Toshihiko Okumura ◽  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Strong Motion ◽  
Seismic Hazard Assessment ◽  
Tohoku Earthquake ◽  
Lessons Learned ◽  
2011 Tohoku Earthquake ◽  
Hazard Maps ◽  
The 2011 Tohoku Earthquake ◽  
Seismic Hazard Maps

Under the guidance of the Headquarters for Earthquake Research Promotion of Japan, we have been carrying out seismic hazard assessment for Japan since the 1995 Hyogo-ken Nanbu Earthquake and have made the National Seismic Hazard Maps for Japan to estimate strong motion caused by earthquakes that could occur in Japan in the future, and show estimated results on these maps. The Hazard Maps consist of two kinds of maps. One kind is a probabilistic seismic hazard map that shows the relation between seismic intensity value and its probability of exceedance within a certain period. The other kind is a scenario earthquake shaking map. In order to promote the use of the National Seismic Hazard Maps, we have developed an open Web system to provide information interactively, and have named this system the Japan Seismic Hazard Information Station (J-SHIS). The 2011 Tohoku Earthquake (Mw9.0) was the largest such event in the recorded history of Japan. This megathrust earthquake was not considered in the National Seismic Hazard Maps for Japan. Based on lessons learned from this earthquake disaster and on experience we have had in the seismic hazardmapping project of Japan, we consider problems and issues to be resolved for seismic hazard assessment and make proposals to improve seismic hazard assessment for Japan.

Empirical Fragility Curves of Buildings in Northern Miyagi Prefecture During the 2011 off the Pacific Coast of Tohoku Earthquake

2016 ◽  
Vol 11 (6) ◽  
pp. 1253-1270 ◽  
Author(s):  
Hao Wu ◽  
◽  
Kazuaki Masaki ◽  
Kojiro Irikura ◽  
Susumu Kurahashi ◽  
...  
Keyword(s):  
Pacific Coast ◽  
Fragility Curves ◽  
Ground Motions ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Kobe Earthquake ◽  
The Pacific ◽  
Miyagi Prefecture

In this study, empirical fragility curves expressed in terms of relationship between damage ratio indices of buildings and ground motion indices were developed in northern Miyagi prefecture located in near-field areas during the 2011 off the Pacific coast of Tohoku Earthquake. The ground motion indices were evaluated from observed ground motions at strong-motion stations and estimated at sites at which no strong-motion accelerometers were deployed during the mainshock. The ground motions at the non-instrumental sites were estimated using the empirical Green’s function method based on bedrock motions inverted from observed records on surfaces from small events that occurred inside the source fault, transfer functions due to underground velocity structures identified from microtremor H/V spectral ratios, and a short-period source model of the mainshock. The findings indicated that the empirical fragility curves as functions of Japan Meteorological Agency (JMA) instrumental seismic intensity during the 2011 Tohoku Earthquake almost corresponded to those during the 1995 Kobe Earthquake and the seven disastrous earthquakes that occurred between 2003 and 2008. However, the empirical fragility curves as functions of peak ground velocity were the lowest. A possible reason for this is that the response spectra of the ground motions in the period ranging from 1.0 s to 1.5 s were small during the 2011 Tohoku Earthquake. Another reason could be the seismic resistant capacities of buildings in the studied districts involved during the 2011 Tohoku Earthquake exceeded those in the cities affected during the 1995 Kobe Earthquake.

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