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Dissipative intraplate faulting during the 2016 M_w 6.2 Tottori, Japan earthquake

Ross, Zachary E. and Kanamori, Hiroo and Hauksson, Egill and Aso, Naofumi (2018) Dissipative intraplate faulting during the 2016 M_w 6.2 Tottori, Japan earthquake. Journal of Geophysical Research. Solid Earth, 123 (2). pp. 1631-1642. ISSN 2169-9313. https://resolver.caltech.edu/CaltechAUTHORS:20180125-083816933

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Abstract

The 2016 M_w 6.2 Tottori earthquake occurred on 21 October 2016 and produced thousands of aftershocks. Here we analyze high-resolution-relocated seismicity together with source properties of the mainshock to better understand the rupture process and energy budget. We use a matched-filter algorithm to detect and precisely locate >10,000 previously unidentified aftershocks, which delineate a network of sharp subparallel lineations exhibiting significant branching and segmentation. Seismicity below 8 km depth forms highly localized fault structures subparallel to the mainshock strike. Shallow seismicity near the main rupture plane forms more diffuse clusters and lineations that often are at a high angle (in map view) to the mainshock strike. An empirical Green's function technique is used to derive apparent source time functions for the mainshock, which show a large amplitude pulse 2–4 s long. We invert the apparent source time functions for a slip distribution and observe a ~16 km^2 patch with average slip ~3.2 m. 93% of the seismic moment is below 8 km depth, which is approximately the depth below which the seismicity becomes very localized. These observations suggest that the mainshock rupture area was entirely within the lower half of the seismogenic zone. The radiated seismic energy is estimated to be 5.7 × 10^(13) J, while the static stress drop is estimated to be 18–27 MPa. These values yield a radiation efficiency of 5–7%, which indicates that the Tottori mainshock was extremely dissipative. We conclude that this inefficiency in energy radiation is likely a product of the immature intraplate environment and the underlying geometric complexity.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/2017JB015077DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2017JB015077/abstractPublisherArticle
ORCID:
AuthorORCID
Ross, Zachary E.0000-0002-6343-8400
Kanamori, Hiroo0000-0001-8219-9428
Hauksson, Egill0000-0002-6834-5051
Aso, Naofumi0000-0001-6255-7494
Additional Information:© 2018 American Geophysical Union. Received 6 OCT 2017; Accepted 19 JAN 2018; Accepted article online 24 JAN 2018; Published online 17 FEB 2018. The manuscript benefitted from constructive comments made by two anonymous reviewers. The authors are grateful to Doug Dreger and Ahyi Kim for their assistance with the Parkfield accelerograms and thank David Shelly for helpful discussions. The Hi-net, K-NET, KiK-net, and F-net data used in this study were provided by the National Research Institute for Earth Science and Disaster Prevention of Japan. The initial seismicity catalog was provided by the Japanese Meteorological Agency (JMA). The slip model and relocated seismicity catalog are provided in the supporting information. The Parkfield data are available from the Center for Engineering Strong Motion Data (strongmotioncenter.org). There are no real or perceived financial conflicts of interest for any author. The study was funded by the Gordon and Betty Moore Foundation, and NSF award EAR-1550704.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
NSFEAR-1550704
Subject Keywords:Earthquake source properties; Fault zone structure; Energy budget; Intraplate faulting; Tottori, Japan; Seismicity
Issue or Number:2
Record Number:CaltechAUTHORS:20180125-083816933
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180125-083816933
Official Citation:Ross, Z. E., Kanamori, H., Hauksson, E., & Aso, N. (2018). Dissipative intraplate faulting During the 2016 Mw 6.2 Tottori, Japan earthquake. Journal of Geophysical Research: Solid Earth, 123, 1631–1642. https://doi.org/10.1002/2017JB015077
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84515
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:25 Jan 2018 17:14
Last Modified:03 Oct 2019 19:19

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