HR: 0800h
AN: T21B-0598    [Abstracts]
TI: Analysis of Stress Field in Caribean Continental Plate - Southern Costa Rica zone - from CMT Solutions
AU: * Zevallos, I
EM: ivanzev@gmail.com
AF: Ivan Zevallos, Urb. Entel Peru D-4, Arequipa, 1234-660, Peru
AU: Quintero, R
EM: rqinter@una.ac.cr
AF: Ronnie Quintero, Campus Omar Dengo apartado 2346-3000, Heredia, 2346-3000, Costa Rica
AU: JImenez, W
AB: During the of period 1984 – 2007, 51 earthquakes were registered with magnitudes above 5.1 mb in southern Costa Rica. Depth distribution of hypocenters shows shallow (0 – 20 km) earthquakes located in continental area; intermediate depth hypocenters (20 – 60 km) corresponding to subduction of the Coco plate under the Caribean plate; and just one earthquake have focus under 60 km depth. We choose hypocenters shallower than 100 km because our goal is to study intraplate stresses. Centroid Moment Tensor solutions for subduction zone earthquakes have inverse fault mechanism. But, in continental area there are evidences of strike slip and normal fault mechanisms. Direction of main stress (σ3) at the southern continental zone is NE-SW; in the Pacific ocean border region, the main stresses are oriented parallel to the coast line; inside the valley region, mechanisms are predominantly strike slip with σ1 in the near N-S direction. This is a complex stress field, with rotation of main stresses in a short space. σ1 is vertical in some continental areas due to influence of elevated terrain. Stress axis paralell to coast line maybe also due to gravitational body force.
DE: 5475 Tectonics (8149)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting