HR: 1340h
AN: S13B-0195    [Abstracts]
TI: Exploring static stress changes along the Costa Rica margin following the March 25, 1990 M w 7.0 Nicoya Gulf earthquake
AU: * Elliott, C E
EM: celliott@nmt.edu
AF: Earth and Environmental Science Dept, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801 United States
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 United States
AU: Lithgow-Bertelloni, C
EM: crlb@umich.edu
AF: Department of Geological Sciences, University of Michigan 425 E. University Ave., Ann Arbor, MI 48109 United States
AU: Protti, M
EM: jprotti@una.ac.cr
AF: Observatorio Vulcanologico y Sismologico de Costa Rica (OVSICORI- UNA), Universidad Nacional, Apartado 2346-3000, Heredia, 2346-3000 Costa Rica
AU: Gonzalez, V
EM: vgonzale@una.ac.cr
AF: Observatorio Vulcanologico y Sismologico de Costa Rica (OVSICORI- UNA), Universidad Nacional, Apartado 2346-3000, Heredia, 2346-3000 Costa Rica
AB: Subduction zone seismicity occurs at some of the largest population centers in the world, increasing the need for greater understanding of the processes that occur in these areas. Among the complexities of the physical relationships involved in subduction zone processes is the role of subducting plate topography in slip and rupture. Subduction zone geometry and the role of bathymetric features, such as seamounts, vary with location. In Costa Rica it has been suggested that subducting seamounts decrease the degree of coupling, thus limiting earthquakes to maximum magnitudes of approximately 7.0. In March 25, 1990, a large earthquake (Mw =7.0, Ms = 6.8) occurred just to the southeast of the Nicoya Peninsula, in Costa Rica. Protti et al [1995], suggest that this event was produced by the subduction of a seamount. In addition, rupture did not occur toward the northwest, a region known as the Nicoya gap, thought to be an area of greater coupling. Inland of this area, seismic activity increased in some areas subsequent to the event, while decreasing in others, suggesting stress variations following this earthquake. We use Coulomb stress modeling to examine the stress changes due to this event, and compare with regional earthquake activity. Slip distribution for the earthquake is estimated from the rupture model as well as aftershocks within 24- 48 hours. We compare models of stress changes with earthquake activity along the megathrust zone as well as inland regions to explore the relationship between seismicity and stress variations in these regions.
DE: 7200 SEISMOLOGY
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Seismology [S]
MN: Fall Meeting 2005