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Published October 2007 | Published + Erratum + Supplemental Material
Journal Article Open

Seismically and geodetically determined nondouble-couple source mechanisms from the 2000 Miyakejima volcanic earthquake swarm

Abstract

The volcanic eruption on Miyakejima, Japan, in 2000 was marked by the largest earthquake swarm ever recorded in Japan, a seismicity migration accompanying a dike intrusion as the dike propagated from Miyakejima to the northwest, and formation of a caldera on Mount Oyama on Miyakejima. In this study, we propose a seismic source model which can be used to model both seismic and geodetic displacements from volcanic earthquakes. Our model, the "crack + double-couple" (CDC) model, combines tensile opening with shear slip along a single fault plane. We find that this model can fit both seismic and GPS data from the 1 July and 30 July earthquakes, the largest two in the Miyakejima sequence. The results of our GPS inversions for these two earthquakes are consistent with the seismic mechanisms and aftershock locations, and the GPS mechanisms successfully forward predict the observed regional seismograms. The 1 July earthquake, located near the northwest tip of the dike, has a large opening component and a geodetic moment about 5 times larger than that inferred from the seismic data alone. The source process for this event consists of tensile failure, which occurred quickly, and a much slower accumulation of shear slip. We apply the CDC model to 16 additional earthquakes from this sequence and find that the CDC model fits the seismic data for these earthquakes at least as well as established seismic moment tensor models.

Additional Information

Copyright 2007 by the American Geophysical Union. Received 9 November 2006; revised 24 May 2007; accepted 4 June 2007; published 25 October 2007. Hypocenter information comes from the Japan Meteorological Agency (JMA) with special help from Fumiko Tajima. The EVT7 hypocenter was relocated by Shin'ichi Sakai of the Earthquake Research Institute, University of Tokyo. Geodetic data came from the Geographic Survey Institute of Japan (GSI), and seismic data were provided by the F-net Broadband Seismograph Network. Contribution 9162 of the Caltech Seismological Laboratory. Minson, S. E., D. S. Dreger, R. Bürgmann, H. Kanamori, and K. M. Larson (2008), Correction to "Seismically and geodetically determined nondouble-couple source mechanisms from the 2000 Miyakejima volcanic earthquake swarm", J. Geophys. Res., 113, B10303, doi:10.1029/2008JB005933.

Attached Files

Published - jgrb15222.pdf

Supplemental Material - jgrb15222-sup-0001-t01.txt

Supplemental Material - jgrb15222-sup-0002-t02.txt

Supplemental Material - jgrb15222-sup-0003-t03.txt

Supplemental Material - jgrb15222-sup-0004-t04.txt

Supplemental Material - jgrb15222-sup-0005-t05.txt

Supplemental Material - jgrb15222-sup-0006-t06.txt

Supplemental Material - jgrb15222-sup-0007-t07.txt

Supplemental Material - jgrb15222-sup-0008-t08.txt

Supplemental Material - jgrb15222-sup-0009-t09.txt

Supplemental Material - jgrb15222-sup-0010-t10.txt

Supplemental Material - jgrb15222-sup-0011-t11.txt

Supplemental Material - jgrb15222-sup-0012-t12.txt

Supplemental Material - jgrb15222-sup-0013-t13.txt

Supplemental Material - jgrb15222-sup-0014-t14.txt

Erratum - jgrb15867.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023