HR: 13:40h
AN: T33E-01 INVITED    [Abstracts]
TI: Seismicity Along the South American Subduction Zone: Large Earthquakes, Tsunamis, and Subduction Zone Complexity
AU: * Bilek, S L
EM: sbilek@nmt.edu
AF: Earth and Environmental Science Dept., New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801,
AB: Earthquakes along the shallow South American subduction zone have variable rupture processes, including great (magnitude larger than Mw=8) events all along the margin as well as slow tsunami earthquakes in Peru. In addition, there is evidence of interaction between earthquake rupture processes and subducting plate complexity in this region, and I review here seismicity characteristics along the South American margin in light of subducting plate heterogeneity. Significant complexity exists on the subducting Nazca plate, including fracture zones and ridges such as the large Nazca Ridge. The Nazca Ridge enters the Peru-Chile trench at 15-16°S along Peru and appears to play a role in segmenting the seismic characteristics of the margin. Within the 20th century, large magnitude earthquakes have occurred in the region of the ridge subduction, as well as north and south of the feature, but no earthquake rupture has spanned the feature to adjacent regions, suggesting that the Nazca Ridge segments the margin. In addition, the Nazca fracture zone, a feature that subducts to the south of the Nazca Ridge, may have acted to slow down rupture during the Mw=8.4 Peru earthquake of 2001. Tsunami earthquakes, those events that produce large tsunami with respect to their size and typically have long rupture durations, occurred along the Peru section of the margin in 1960 and 1996. These may also be affected by subduction zone heterogeneity, as one mechanism for these tsunami earthquakes includes rupture through low velocity, near- trench interface materials. Presence of this low velocity material will influence other earthquake ruptures as well, and I will present results that suggest other slow events along the Peru section of the margin to the south of the 2 tsunami earthquakes.
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting