Variations and Controls on the Up- and Down-Dip Limits of the Central America Seismogenic Zone

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

EAR-0229876 Susan Y. Schwartz A first-order characterization of the seismogenic zone, including its geometry and up and down-dip limits is nearly established in northern and central Costa Rica. This was accomplished through the deployment of two onshore/offshore seismic networks directly above the seismogenic zone that were part of a MARGIN's funded multidisciplinary seismogenic zone experiment (CRSEIZE). This proposal seeks to: 1) use data collected during this experiment in conjunction with local network data to establish a similar first-order characterization of the seismogenic zone in Nicaragua; 2) perform a detailed investigation of the variations in the transition from inter to intra plate seismicity in northern Costa Rica and Nicaragua; and 3) evaluate thermal and mechanical models that have been proposed to control this transition. These golas will be accomplished by simultaneously inverting local travel time data in northern Costa Rica and Nicaragua to obtain an high resolution, three-dimensional, P and S wave velocity structure and accurate hypocentral locations. Earthquake locations coupled with focal mechanism determinations will allow the active seimogenic zone to be identified in southern Nicaragua, where the addition of stations from the northern Costa Rica (Nicoya) network greatly improves station coverage and hypocentral accuracy.