3-D GRACE gravity model for the 2011 Japan earthquake

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• 作者：RAMBHATLA G SASTRY ; Mahendra K SONKER
• 关键词：GRACE gravity ; 2011 Tohoku ; Oki earthquake ; gravity pyramid model ; tsunamigenic earthquake
• 刊名：Journal of Earth System Science
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：126
• 期：1
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Earth Sciences, general; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics);
• 出版者：Springer India
• ISSN：0973-774X
• 卷排序：126

文摘

The GRACE mission has contributed to the seismic characterization of major earthquakes in offshore regions of the world. Here, we isolate satellite gravity signal (μGal range) for the Japan Earthquake of 2011 using a difference method. Contrary to the existing gravity models, we propose a unit vertical pyramid based five-layer 3-D thrust fault model, which extends to the hypocenter and honors the ocean water layer and sea floor upheaval also. Our model partly uses existing seismological information (hypocenter depth of 32 km, rupture length of 300 km and vertical slip of 4 m), provides a snapshot of episodic subduction of the Pacific Plate below the Atlantic Plate and its gravity response closely matches the observed gravity (RMS error of 3.4012×10−13μGal), fully accounting for co-seismic mass redistribution including sea surface deformation. Our inferred rupture length, rupture velocity, average seismic moment magnitude and momentum, respectively, are 300 km, 4.49 km/s, 1.152×1021−1.8816×1021 N m and 2.319×106 GNs, which fairly agree with the literature. Further, our model inferred momentum at the sea floor corresponds to an area pulse that led to Tsunami generation.