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Fault parameters and tsunami excitation of the May 23, 1989, MacQuarie Ridge Earthquake

Satake, Kenji and Kanamori, Hiroo (1990) Fault parameters and tsunami excitation of the May 23, 1989, MacQuarie Ridge Earthquake. Geophysical Research Letters, 17 (7). pp. 997-1000. ISSN 0094-8276. doi:10.1029/GL017i007p00997.

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The Macquarie Ridge earthquake of May 23, 1989, is one of the largest events in the last decade. Furthermore, it is the largest strike-slip earthquake ever recorded instrumentally. We analyzed long-period surface waves and body waves recorded at global networks (GDSN, IRIS, GEOSCOPE, and IDA) to estimate the fault parameters and computed tsunamis from the estimated parameters. The Centroid Moment Tensor (CMT) solution from surface waves shows that the mechanism is almost pure strike-slip with one of the nodal planes parallel to the strike of the Macquarie Ridge. The seismic moment is 1.6 × 10^(21) Nm (× 10^(28) dyn•cm) and the corresponding moment magnitude is M_w =8.1. Teleseismic P and S waves from 10 stations with good azimuthal coverage are used to model the temporal and spatial distribution of the subevents. Four subevents are located sequentially from south to north along the ridge system in about 30 sec. All of them have a mechanism similar to the CMT solution. The fault length is estimated to be about 120 km from the subevent and the aftershock distributions. The rapture propagates from south to north at a relatively high speed. The average slip on the fault depends on the estimate of the fault width, but is probably larger than 9 m. A large strike-slip earthquake like this event produces significant vertical displacements on the ocean bottom and excites tsunamis. Computation of tsunamis using the estimated fault parameters predicts that small tsunamis are expected at Australia and New Zealand. In fact, small tsunamis were observed on the southern coast of Australia.

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URLURL TypeDescription
Satake, Kenji0000-0002-3368-3085
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1990 The American Geophysical Union. Paper number 90GL00714. Received January 31, 1990; Accepted March 15, 1990. We thank Barbara Romanowicz and Goran Ekstrom for providing us with GEOSCOPE data, Helen Anderson and Terry Webb for providing us with tide gauge data from New Zealand and related information, and Heidi Houston for reviewing the manuscript. This work was supported by USGS grant No 14-08-001-G1356 and NSF grant EAR-89-15987. KS is supported by Fellowship for Research Abroad from Japan Society for the Promotion of Science. Contribution No. 4833, Division of Geological and Planetary Sciences, California Institute of Technology.
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Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
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Caltech Division of Geological and Planetary Sciences4833
Issue or Number:7
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Official Citation:Satake, K., & Kanamori, H. (1990). Fault parameters and tsunami excitation of the May 23, 1989, MacQuarie Ridge Earthquake. Geophysical Research Letters, 17(7), 997-1000. doi: 10.1029/GL017i007p00997
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51305
Deposited By: Joanne McCole
Deposited On:05 Nov 2014 22:50
Last Modified:10 Nov 2021 19:08

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