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Consecutive Ruptures on a Complex Conjugate Fault System During the 2018 Gulf of Alaska Earthquake
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  • Shinji Yamashita,
  • Yuji Yagi,
  • Ryo Okuwaki,
  • Kousuke Shimizu,
  • Ryoichiro Agata,
  • Yukitoshi Fukahata
Shinji Yamashita
University of Tsukuba, University of Tsukuba, University of Tsukuba, University of Tsukuba

Corresponding Author:[email protected]

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Yuji Yagi
University of Tsukuba, University of Tsukuba, University of Tsukuba, University of Tsukuba
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Ryo Okuwaki
University of Tsukuba, University of Tsukuba, University of Tsukuba, University of Tsukuba
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Kousuke Shimizu
University of Tsukuba, University of Tsukuba, University of Tsukuba, University of Tsukuba
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Ryoichiro Agata
Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology, Japan Agency for Marine-Earth Science and Technology
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Yukitoshi Fukahata
Kyoto University, Kyoto University, Kyoto University, Kyoto University
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Abstract

We developed a flexible finite-fault inversion method for teleseismic P waveforms to obtain a detailed rupture process of a complex multiple-fault earthquake. We estimate the distribution of potency-rate density tensors on an assumed model plane to clarify rupture evolution processes, including variations of fault geometry. We applied our method to the 23 January 2018 Gulf of Alaska earthquake by representing slip on a projected horizontal model plane at a depth of 33.6 km to fit the distribution of aftershocks occurring within one week of the mainshock. The obtained source model, which successfully explained the complex teleseismic P waveforms, shows that the 2018 earthquake ruptured a conjugate system of N-S and E-W faults. The spatiotemporal rupture evolution indicates irregular rupture behavior involving a multiple-shock sequence, which is likely associated with discontinuities in the fault geometry that originated from E-W sea-floor fracture zones and N-S plate-bending faults.
16 Mar 2021Published in Scientific Reports volume 11 issue 1. 10.1038/s41598-021-85522-w