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Rupture Directivity Analysis of the 2018 Hokkaido Eastern Iburi Earthquake and Its Seismotectonic Implication

Zang, Chong and Ni, Sidao and Shen, Zhichao (2019) Rupture Directivity Analysis of the 2018 Hokkaido Eastern Iburi Earthquake and Its Seismotectonic Implication. Seismological Research Letters, 90 (6). pp. 2121-2131. ISSN 0895-0695. https://resolver.caltech.edu/CaltechAUTHORS:20191003-113816784

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Abstract

The M_w 6.6 Hokkaido Eastern Iburi earthquake striking southern Hokkaido Island on 5 September 2018 was a disastrous and peculiar event. In contrast to the usually shallow crustal earthquakes, this event occurred at a hypocentral depth about 37 km, close to the Moho discontinuity. To infer the rupture feature of the 2018 Hokkaido earthquake, we determine focal mechanism and centroid depth of the event with inversion of teleseismic waveforms. The result reveals that the centroid (at depth about 26 km) of this thrust earthquake is shallower than the hypocenter, which suggests the upward rupture propagation and dominant rupture in the lower crust. We also investigate the causative fault and rupture directivity based on waveform modeling. The steeply dipping fault (70°) with strike in the north–south direction is preferred to be the causative fault. The total dimension of rupture is estimated to be about 30 km, based on the aftershock distribution and rupture directivity. We propose that a seismogenic model with low temperature and complex stress field in the lower crust above the subduction‐zone interface may explain this event.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1785/0220190131DOIArticle
ORCID:
AuthorORCID
Ni, Sidao0000-0003-2988-4850
Shen, Zhichao0000-0003-0458-5264
Additional Information:© 2019 Seismological Society of America. Published Online 2 October 2019. Thanks to three reviewers for careful reading and suggestions. The authors thank the Incorporated Research Institutions for Seismology Data Management Center (IRIS‐DMC) for providing seismic waveform data and Japan Meteorological Agency (JMA) for providing aftershock catalogs. The authors thank JMA, National Earthquake Information Center (NEIC), GeoForschungsZentrum (GFZ), and Global Centroid Moment Tensor (CMT) for providing point‐source parameters information. The authors also thank Global Volcanism Program (GVP) for their global volcano database. This study is supported by funding from the National Natural Science Foundation of China (41874068).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
National Natural Science Foundation of China41874068
Issue or Number:6
Record Number:CaltechAUTHORS:20191003-113816784
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191003-113816784
Official Citation:Chong Zang, Sidao Ni, Zhichao Shen; Rupture Directivity Analysis of the 2018 Hokkaido Eastern Iburi Earthquake and Its Seismotectonic Implication. Seismological Research Letters ; 90 (6): 2121–2131. doi: https://doi.org/10.1785/0220190131
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99056
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Oct 2019 23:05
Last Modified:29 Oct 2019 17:04

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