TY - JOUR
T1 - Stationarity of aftershock activities of the 2016 Central Tottori Prefecture earthquake revealed by dense seismic observation
AU - Iio, Yoshihisa
AU - Matsumoto, Satoshi
AU - Yamashita, Yusuke
AU - Sakai, Shin’ichi
AU - Tomisaka, Kazuhide
AU - Sawada, Masayo
AU - Iidaka, Takashi
AU - Iwasaki, Takaya
AU - Kamizono, Megumi
AU - Katao, Hiroshi
AU - Kato, Aitaro
AU - Kurashimo, Eiji
AU - Teguri, Yoshiko
AU - Tsuda, Hiroo
AU - Ueno, Takashi
N1 - Funding Information:
This study was partly supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan under its Earthquake and Volcano Hazards Observation and Research Program, and KAKENHI Grant Number 26109006. Acknowledgements
Funding Information:
We are grateful to the landowners and staffs of Misasa town and Kurayoshi city in the Tottori prefecture for their great help in the seismic observations. We are also grateful to the staff of the Tottori prefecture office for their great help and thoughtful arrangements for our study. We used seismic data from the National Research Institute for Earth Science and Disaster Prevention (NIED), the Japan Meteorological Agency (JMA), and Kyoto University. We are grateful for Airi Nagaoka (DPRI), Miwako Ando, Shin’ichi Tanaka, Takeo Yagi (ERI) who were in charge of the installation of observation stations, Satoshi Ikezawa, Hironori Otsuka, Ayaka Saiki, Chikaaki Fujita, Masataka Masuda, Koji Miyakawa (ERI) and students and staffs of SVO who were in charge of the preparation of instruments. We are grateful to Shigeki Horiuchi for his great help for data processing. We are grateful to the staff of the “Manten” project, Mie Tanaka, and Rie Mizushima for their great help in seismic observations and data processing. We are grateful to the lead guest editor and an anonymous reviewer for their thoughtful reviews and detailed comments. We would like to thank Editage (http://www.editage.com) for English language editing.
Publisher Copyright:
© 2020, The Author(s).
PY - 2020/12/1
Y1 - 2020/12/1
N2 - To clarify the relationship between earthquake occurrence and fluid, we analyzed data from a dense aftershock-observation network with 69 high-gain short-period seismographs installed immediately after the mainshock occurrence (October 21) in the aftershock area of the 2016 Central Tottori Prefecture earthquake. We determined the hypocenters and focal mechanisms of the aftershocks very precisely in the period from October 22 to December 15. We then investigated the temporal changes in the spatial distributions of hypocenters and T-axis azimuths of focal mechanisms. The distributions of aftershock hypocenters and T-axis azimuths are basically temporally stable, except those in limited portions in the shallow layer near the western edge of the aftershock area, where rapid decrease of aftershocks with T-axis azimuths of WSW to west was observed. If fluid rises from the lower crust due to fault rupture, the locations of aftershocks and focal mechanisms may change over time, especially in the deepest part of the aftershock region. However, the temporal change in these parameters was not apparent at depth. These observations suggest that the aftershock activity of the Central Tottori Prefecture earthquake was controlled mainly by stress concentration rather than strength reduction due to high fluid pressure.[Figure not available: see fulltext.].
AB - To clarify the relationship between earthquake occurrence and fluid, we analyzed data from a dense aftershock-observation network with 69 high-gain short-period seismographs installed immediately after the mainshock occurrence (October 21) in the aftershock area of the 2016 Central Tottori Prefecture earthquake. We determined the hypocenters and focal mechanisms of the aftershocks very precisely in the period from October 22 to December 15. We then investigated the temporal changes in the spatial distributions of hypocenters and T-axis azimuths of focal mechanisms. The distributions of aftershock hypocenters and T-axis azimuths are basically temporally stable, except those in limited portions in the shallow layer near the western edge of the aftershock area, where rapid decrease of aftershocks with T-axis azimuths of WSW to west was observed. If fluid rises from the lower crust due to fault rupture, the locations of aftershocks and focal mechanisms may change over time, especially in the deepest part of the aftershock region. However, the temporal change in these parameters was not apparent at depth. These observations suggest that the aftershock activity of the Central Tottori Prefecture earthquake was controlled mainly by stress concentration rather than strength reduction due to high fluid pressure.[Figure not available: see fulltext.].
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U2 - 10.1186/s40623-020-01161-x
DO - 10.1186/s40623-020-01161-x
M3 - Letter
AN - SCOPUS:85082876681
VL - 72
JO - Earth, Planets and Space
JF - Earth, Planets and Space
SN - 1343-8832
IS - 1
M1 - 42
ER -