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Indian Ocean ridge seismicity observed with a permanent hydroacoustic network
Author(s) -
Hanson Jeffrey A.,
Bowman J. Roger
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021931
Subject(s) - seismology , induced seismicity , geology , ridge , seamount , bathymetry , indian ocean , hotspot (geology) , bathymetric chart , mid ocean ridge , oceanography , paleontology , basalt
The distribution of earthquakes along the Indian Ocean ridge system between January 18 and October 20, 2003 is investigated using data from two hydrophone stations of the International Monitoring System's global network. Coherent array processing of earthquake‐induced hydroacoustic T‐waves is used to determine precise arrival times and back azimuths that allow automatic location of the earthquakes. We observed 4725 events throughout the Indian Ocean Basin. Here, we examine 1146 earthquakes from the Central and Southeast Indian Ridge. Source level estimates from the hydroacoustic signals indicate that the hydroacoustic network is at least one magnitude unit more sensitive than the seismic network for Indian Ocean ridge earthquakes. The seismicity primarily clusters at ridge transform offsets. Events are observed off the ridge axis near Boomerang and St. Pierre Seamounts, the active expression of the Amsterdam‐St. Paul Hotspot. Seismic gaps are observed at several ridge segments with anomalous bathymetric highs.