Investigation on the Postseismic Deformation Associated with the 2011 Tohoku Earthquake Based on Terrestrial and Seafloor Geodetic Observations: To Evaluate the Further Seismic Hazard Potential on the Plate Interface Beneath the Northeastern Japanese Islands

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.

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Coseismic and postseismic deformation estimation of the 2011 Tohoku earthquake in Kanto Region, Japan, using InSAR time series analysis and GPS

Remote Sensing of Environment ◽

10.1016/j.rse.2015.07.016 ◽

2015 ◽

Vol 168 ◽

pp. 374-387 ◽

Cited By ~ 4

Author(s):

Tamer ElGharbawi ◽

Masayuki Tamura

Keyword(s):

Time Series ◽

Time Series Analysis ◽

Tohoku Earthquake ◽

2011 Tohoku Earthquake ◽

Postseismic Deformation ◽

The 2011 Tohoku Earthquake ◽

Series Analysis ◽

Kanto Region

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Spatio-temporal characteristics of frictional properties on the subducting Pacific Plate off the east of Tohoku district, Japan estimated from stress drops of small earthquakes

Earth Planets and Space ◽

10.1186/s40623-020-01326-8 ◽

2021 ◽

Vol 73 (1) ◽

Author(s):

Takuji Yamada ◽

Meitong Duan ◽

Jun Kawahara

Keyword(s):

Stress Drop ◽

Tohoku Earthquake ◽

Pacific Plate ◽

2011 Tohoku Earthquake ◽

Plate Interface ◽

The 2011 Tohoku Earthquake ◽

Frictional Properties ◽

Frictional Strength ◽

Spatio Temporal ◽

Stress Drops

AbstractThe east coast of the Tohoku district, Japan has a high seismicity, including aftershocks of the 2011 M9 Tohoku earthquake. We analyzed 1142 earthquakes with $$4.4 \le M_{W} \le 5.0$$ 4.4 ≤ M W ≤ 5.0 that occurred in 2003 through 2018 and obtained spatio-temporal pattern of stress drop on the Pacific Plate that subducts beneath the Okhotsk Plate. Here we show that small earthquakes at edges of a region with a large slip during the 2011 Tohoku earthquake had high values of stress drop, indicating that the areas had a high frictional strength and suppressed the coseismic slip of the 2011 Tohoku earthquake. In addition, stress drops of small earthquakes in some of the areas likely decreased after the 2011 Tohoku earthquake. This indicates that the frictional strength decreased at the areas due to the following aftershocks of the 2011 Tohoku earthquake, consistent with a high aftershock activity. This also supports that the frictional properties on a subducting plate interface can be monitored by stress drops of small earthquakes, as pointed out by some previous studies.

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Spatio-temporal Characteristics of Frictional Properties on the Subducting Pacific Plate Off the East of Tohoku District, Japan Estimated from Stress Drops of Small Earthquakes

10.21203/rs.3.rs-39395/v1 ◽

2020 ◽

Author(s):

Takuji Yamada ◽

Meitong Duan ◽

Jun Kawahara

Keyword(s):

Stress Drop ◽

Tohoku Earthquake ◽

Pacific Plate ◽

2011 Tohoku Earthquake ◽

Plate Interface ◽

The 2011 Tohoku Earthquake ◽

Frictional Properties ◽

Frictional Strength ◽

Spatio Temporal ◽

Stress Drops

Abstract The east coast of the Tohoku district, Japan has a high seismicity, including aftershocks of the 2011 M9 Tohoku earthquake. We analyzed 1142 earthquakes with $4.4 \le M_{W} \le 5.0$ that occurred in 2003 through 2018 and obtained spatio-temporal pattern of stress drop on the Pacific Plate that subducts beneath the Okhotsk Plate. Here we show that small earthquakes at edges of a region with a large slip during the 2011 Tohoku earthquake had high values of stress drop, indicating that the areas had a high frictional strength and suppressed the coseismic slip of the 2011 Tohoku earthquake. In addition, stress drops of small earthquakes in some of the areas likely decreased after the 2011 Tohoku earthquake. This indicates that the frictional strength decreased at the areas due to the following aftershocks of the 2011 Tohoku earthquake, consistent with a high aftershock activity. This also supports that the frictional properties on a subducting plate interface can be monitored by stress drops of small earthquakes, as pointed out by some previous studies.

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