TY - JOUR
T1 - Coseismic slip model of offshore moderate interplate earthquakes on March 9, 2011 in Tohoku using tsunami waveforms
AU - Kubota, Tatsuya
AU - Hino, Ryota
AU - Inazu, Daisuke
AU - Ito, Yoshihiro
AU - Iinuma, Takeshi
AU - Ohta, Yusaku
AU - Suzuki, Syuichi
AU - Suzuki, Kensuke
N1 - Funding Information:
The authors thank the Earthquake Research Institute of the University of Tokyo for the use of tsunami data recorded by the cabled ocean-bottom pressure sensors of the observatory off Kamaishi. The coastal tide waveforms used in this study were recorded by the Japan Meteorological Agency (JMA), the Japan Coast Guard (JCG), the Ports and Harbors Bureau under the Ministry of Land, Infrastructure, Transport, and Tourism (MLIT), and the Port and Airport Research Institute (PARI). The authors wish to thank Dr. Tatsuhiko Saito of the National Research Institute for Earth Science and Disaster Prevention (NIED), for the Fortran code to calculate the tsunamis, as well as helpful comments. The authors deeply thank two anonymous reviewers for constructive comments on the manuscript. This study was supported by the research project “Research concerning Interaction between the Tokai, Tonankai, and Nankai earthquakes” of the Ministry of Education, Culture, Sports, Science and Technology , and by JSPS KAKENHI (A) Grant Numbers JP20244070 and JP26000002 . The figures in this paper were prepared using Generic Mapping Tools (GMT) ( Wessel and Smith, 1998 ). The authors used the English language editing service Editage ( www.editage.jp ).
Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2017/1/15
Y1 - 2017/1/15
N2 - We estimated the coseismic slip distribution associated with the Mw 7.2 and 6.5 foreshocks of the 2011 Tohoku-Oki earthquake based on analysis of the tsunami waveform records obtained just above their focal areas. The results show that the main rupture areas of each of the foreshocks do not overlap with each other, and show a distribution that is complementary to the postseismic slip area of the first Mw 7.2 foreshock as well as to the epicenters of smaller earthquakes during foreshock activity. After the second largest foreshock, seismicity increased in the area between the rupture area of the second largest foreshock and the mainshock epicenter, suggesting propagation of aseismic slip towards the mainshock epicenter. The calculated stress drop of the second largest foreshock was smaller than the largest one, implying strength reduction during the postseismic period of the largest foreshock. Based on a comparison of coastal tsunami records, it is suggested that the asperity ruptured in the M 7.0 earthquake in 1981 ruptured again during the largest foreshock in 2011, but it expanded to the updip side of the 1981 rupture area and became larger in magnitude, exemplifying the irregularity of earthquake recurrence in the area.
AB - We estimated the coseismic slip distribution associated with the Mw 7.2 and 6.5 foreshocks of the 2011 Tohoku-Oki earthquake based on analysis of the tsunami waveform records obtained just above their focal areas. The results show that the main rupture areas of each of the foreshocks do not overlap with each other, and show a distribution that is complementary to the postseismic slip area of the first Mw 7.2 foreshock as well as to the epicenters of smaller earthquakes during foreshock activity. After the second largest foreshock, seismicity increased in the area between the rupture area of the second largest foreshock and the mainshock epicenter, suggesting propagation of aseismic slip towards the mainshock epicenter. The calculated stress drop of the second largest foreshock was smaller than the largest one, implying strength reduction during the postseismic period of the largest foreshock. Based on a comparison of coastal tsunami records, it is suggested that the asperity ruptured in the M 7.0 earthquake in 1981 ruptured again during the largest foreshock in 2011, but it expanded to the updip side of the 1981 rupture area and became larger in magnitude, exemplifying the irregularity of earthquake recurrence in the area.
KW - 2011 Tohoku-Oki earthquake
KW - foreshock
KW - seafloor observations
KW - subduction zone
KW - tsunami
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U2 - 10.1016/j.epsl.2016.10.047
DO - 10.1016/j.epsl.2016.10.047
M3 - Article
AN - SCOPUS:85003475374
VL - 458
SP - 241
EP - 251
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
ER -