Quasi-static slip on the plate boundary associated with the 2003 M8.0 Tokachi-oki and 2004 M7.1 off-Kushiro earthquakes, Japan |
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| Authors: | Naoki Uchida Satoshi Yui Satoshi Miura Toru Matsuzawa Akira Hasegawa Yoshinobu Motoya Minoru Kasahara |
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| Institution: | aResearch Center for Prediction of Earthquakes and Volcanic Eruptions, Tohoku University, Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578, Japan;bInstitute of Seismology and Volcanology, Hokkaido University, N10S8 Kita-ku, Sapporo 060-0810, Japan;cGeographical Survey Institute, 1Kitasato, Tsukuba 305-0811, Japan |
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| Abstract: | We analyzed small repeating earthquakes recorded over a 13-year period and GPS data recorded over an 8-month period to estimate interplate quasi-static slip associated with the 2003 Tokachi-oki earthquake (M8.0) and the 2004 off-Kushiro earthquake (M7.1). The repeating-earthquake analysis revealed that the slip rate near the source region of the Tokachi-oki earthquake was relatively low (< 5 cm/year) prior to the earthquake; however, in the last 3 years leading up to the event, a minor acceleration in slip occurred upon the deeper extension of the coseismic slip area of the earthquake. Repeating-earthquake and GPS data indicate that large amounts of afterslip occurred around the rupture area following the earthquake; the afterslip mainly propagated to the east of the coseismic slip area. We also infer that the occurrence of the 2004 off-Kushiro earthquake, located about 100 km northeast of the epicenter of the Tokachi-oki earthquake, was advanced by the afterslip associated with the Tokachi-oki earthquake. |
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| Keywords: | Small repeating earthquake GPS data analysis Quasi-static slip Afterslip Subduction tectonics |
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