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Strain anomalies induced by the 2011 Tohoku Earthquake (Mw 9.0) as observed by a dense GPS network in northeastern Japan
| Title: | Strain anomalies induced by the 2011 Tohoku Earthquake (Mw 9.0) as observed by a dense GPS network in northeastern Japan |
| Authors: | Ohzono, Mako Browse this author | | Yabe, Yasuo Browse this author | | Iinuma, Takeshi Browse this author | | Ohta, Yusaku Browse this author | | Miura, Satoshi Browse this author | | Tachibana, Kenji Browse this author | | Sato, Toshiya Browse this author | | Demachi, Tomotsugu Browse this author |
| Keywords: | Coseismic strain anomaly | | 2011 Tohoku Earthquake | | structural heterogeneity | | strain concentration zone |
| Issue Date: | 2012 |
| Publisher: | Terra Scientific Publishing Company |
| Journal Title: | Earth, Planets and Space |
| Volume: | 64 |
| Issue: | 12 |
| Start Page: | 1231 |
| End Page: | 1238 |
| Publisher DOI: | 10.5047/eps.2012.05.015 |
| Abstract: | We have evaluated an anomalous crustal strain in the Tohoku region, northeastern Japan associated with a step-like stress change induced by the 2011 off the Pacific coast of Tohoku Earthquake (Mw 9.0). Because the source area of the event was extremely large, the gradient of the observed eastward coseismic displacements that accompanied uniform stress change had a relatively uniform EW extension in northeastern Japan. Accordingly, the deformation anomaly, which is determined by subtracting the predicted displacement in a half-space elastic media from the observed displacement, should reflect the inhomogeneity of the rheology, or stiffness, of the crust. The difference of the EW extension anomaly between the forearc and backarc regions possibly indicates a dissimilarity of stiffness, depending on the crustal structure of the Tohoku region. The Ou-backbone range - a strain concentration zone in the interseismic period - shows an extension deficit compared with predictions. A low viscosity in the lower crust probably induced a relatively small extension. Meanwhile, the northern part of the Niigata-Kobe tectonic zone, another strain concentration zone, indicates an excess of extensional field. This is probably caused by a low elastic moduli of the thick sedimentation layer. The detection of strain anomalies in the coseismic period enables a new interpretation of the deformation process at strain concentration zones. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/54521 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 大園 真子
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