HR: 0800h
AN: DI51A-0289    [Abstracts]
TI: High-precision relative earthquake locations in the Tonga-Kermadec subduction zone and implications for the mechanisms of deep-focus earthquakes
AU: * Yu, W
EM: yu@mantle.geo.sunysb.edu
AF: Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, N.W., Washington D.C., 20015, United States
AU: Wen, L
EM: Lianxing.Wen@sunysb.edu
AF: Department of Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, United States
AB: High-precision determination of earthquake location is important to the understanding of the physical mechanisms of the earthquakes. Using repeating seismic events is a powerful tool for determining high- precision relative locations of the events and studying temporal property change of the Earth. In this study, we focus on studying the repeating events occurring in the Tonga-Kermadec subduction zone, the most seismically active region for producing deep-focus earthquakes. We assemble seismic data for more than 7600 earthquakes occurring in the Tonga-Kermadec subduction zone in the time span of 1990-2006, with mb greater than 4.6. 119 high-quality repeating events are found among 115000 potential event pairs. The depth distribution of the repeating events is bimodal, with 64 in the top 100 km, 50 at a depth below 500 km, and 5 between 100 km and 500 km. For the shallow repeating earthquakes (event depth less than 100 km), the minimum and maximum recurrence intervals are 3 months and 14.5 years, respectively. The closest separation of the repeating events is in the same location, but different in depth by 0.5 km. For the deep-focus repeating events (event depth greater than 500 km), the recurrence interval ranges from 7 days to 13 years. The closest separation of the events is 2.4 km in horizontal space and 1 km in depth. For the intermediate-depth repeating earthquakes, the minimum and maximum recurrence intervals are 1.3 years and 7 years, respectively. The closest separation of the repeating events is 7.8 km in horizontal space and 6 km in depth. Among all the discovered deep-focus repeating events, five have different earthquake radiation patterns. The best one has occurrence interval of 5.1 years, separated by 10 km in horizontal space and 16 km in depth. We will discuss in detail the geographic and depth distributions, repeating pattern, relative location of the repeating earthquakes, as well as implications for various proposed mechanisms for deep-focus earthquakes.
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Study of the Earth's Deep Interior [DI]
MN: 2007 Fall Meeting