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Source depth dependence of micro-tsunamis recorded with ocean-bottom pressure gauges: The January 28, 2000 Mw 6.8 earthquake off Nemuro Peninsula, Japan

Earth and Planetary Science Letters

By:
, , , , , , and
DOI: 10.1016/S0012-821X(03)00040-2

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Abstract

Micro-tsunami waves with a maximum amplitude of 4-6 mm were detected with the ocean-bottom pressure gauges on a cabled deep seafloor observatory south of Hokkaido, Japan, following the January 28, 2000 earthquake (Mw 6.8) in the southern Kuril subduction zone. We model the observed micro-tsunami and estimate the focal depth and other source parameters such as fault length and amount of slip using grid searching with the least-squares method. The source depth and stress drop for the January 2000 earthquake are estimated to be 50 km and 7 MPa, respectively, with possible ranges of 45-55 km and 4-13 MPa. Focal depth of typical inter-plate earthquakes in this region ranges from 10 to 20 km and stress drop of inter-plate earthquakes generally is around 3 MPa. The source depth and stress drop estimates suggest that the earthquake was an intra-slab event in the subducting Pacific plate, rather than an inter-plate event. In addition, for a prescribed fault width of 30 km, the fault length is estimated to be 15 km, with possible ranges of 10-20 km, which is the same as the previously determined aftershock distribution. The corresponding estimate for seismic moment is 2.7??1019 Nm with possible ranges of 2.3??1019-3.2??1019Nm. Standard tide gauges along the nearby coast did not record any tsunami signal. High-precision ocean-bottom pressure measurements offshore thus make it possible to determine fault parameters of moderate-sized earthquakes in subduction zones using open-ocean tsunami waveforms. Published by Elsevier Science B. V.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Source depth dependence of micro-tsunamis recorded with ocean-bottom pressure gauges: The January 28, 2000 Mw 6.8 earthquake off Nemuro Peninsula, Japan
Series title:
Earth and Planetary Science Letters
DOI:
10.1016/S0012-821X(03)00040-2
Volume
208
Issue:
3-4
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Earth and Planetary Science Letters
First page:
305
Last page:
318