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Published November 2017 | Supplemental Material + Published
Journal Article Open

The 2016 Kumamoto M_w = 7.0 earthquake: a significant event in a fault-volcano system

Abstract

The 2016 Kumamoto earthquake sequence occurred on the Futagawa–Hinagu fault zone near the Aso volcano on Kyushu island. The sequence was initiated with two major (M_w ≥ 6.0) foreshocks, and the mainshock (M_w = 7.0) occurred 25 h after the second major foreshock. We combine GPS, strong motion, synthetic aperture radar images, and surface offset data in a joint inversion to resolve the kinematic rupture process of the mainshock and coseismic displacement of the foreshocks. The joint inversion results reveal a unilateral rupture process for the mainshock involving sequential rupture of four major asperities. The slip area of the foreshocks and mainshock and the aftershock loci form a detailed complementary pattern. The mainshock rupture terminates near the rim of the caldera, leaving a ~10 km long gap of aftershocks. This area is characterized by high temperature and low shear wave velocity, density, and resistivity, which may be related to the partially melted geothermal condition. Ductile material property near the volcano may act as a "material barrier" to the dynamic rupture. Topographic weight of the caldera increases compressional normal stress on the fault plane, which may behave as a "stress barrier." Long-term seismic hazard and deformation behaviors related to these two types of barriers are discussed in terms of the associated frictional mechanism. Significant postseismic creeps observed near the volcano area indicates a velocity strengthening frictional behavior near the rupture termination, which confirms that the "material barrier" mechanism is likely the dominant rupture termination mechanism.

Additional Information

© 2017 American Geophysical Union. Received 5 JUN 2017; Accepted 18 OCT 2017; Accepted article online 20 OCT 2017. Data analysis made use of GMT, SAC, and Matlab. The strong motion data are recorded by K-net and KiK-net and accessed through NIED. All original GEONET RINEX data are provided to Caltech by the Geospatial Information Authority (GSI) of Japan. Original ALOS-2 radar images are copyright 2016 by the Japanese Aerospace Exploration Agency (JAXA) and were provided under JAXA ALOS RA4 projects P1385, P1372, and P1303 and through the CEOS Disasters Seismic Pilot. This work contains Copernicus data from the Sentinel-1A satellite provided by the European Space Agency (ESA). Part of this research was supported by the NASA Earth Surface and Interior focus area and performed at the Jet Propulsion Laboratory, California Institute of Technology. We thank Mark Simons, Hiroo Kanamori, Jean-Philippe Avouac, Donald Helmberger, Jean-Paul Ampuero, Naofumi Aso, and Adriano Gualandi for their suggestive discussion. This work was supported in part by National Basic Research Program of China grant 2012CB417301 and NSF grant 1447107 awarded to Mark Simons and Jean Paul Ampuero.

Attached Files

Published - Yue_et_al-2017-Journal_of_Geophysical_Research__Solid_Earth.pdf

Supplemental Material - jgrb52388-sup-0001-2017JB014525_ds01.txt

Supplemental Material - jgrb52388-sup-0002-2017JB014525_ds02.txt

Supplemental Material - jgrb52388-sup-0003-2017JB014525_ds03.txt

Supplemental Material - jgrb52388-sup-0004-2017JB014525_SI.docx

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Additional details

Created:
August 21, 2023
Modified:
October 17, 2023