Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica
نویسندگان
چکیده
[1] Characterizing the hydration state of the forearc mantle wedge yields valuable information on frictional stability at the downdip edge of subduction megathrusts. Simultaneous inversion of Pand S-wave arrival times collected as part of the Costa Rica Seismogenic Zone Experiment yields 1D and 3D Pand S-wave velocity models (VP and VS) for the Nicoya Peninsula segment of the Middle America Trench. Nicoya Peninsula 1D velocity models show similar velocity gradients to country-wide 1D velocity models from 5–30 km depth but diverge at expected Moho depths due to proximity to the subducting Cocos plate. 3D VP values range from 7.2– 7.6 km/sec in the forearc mantle wedge. Receiver functions computed at Global Seismic Network station JTS in northwestern Costa Rica confirm these VP values, yield VP/VS of 1.85, and place the continental Moho at 36 ± 4 km depth. VP and VP/VS are consistent with 15–25% serpentinization of the forearc mantle wedge.
منابع مشابه
Active deformation near the Nicoya Peninsula, northwestern Costa Rica, between 1996 and 2010: Interseismic megathrust coupling
[1] We use campaign and continuous GPS measurements at 49 sites between 1996 and 2010 to describe the long-term active deformation in and near the Nicoya Peninsula, northwestern Costa Rica. The observed deformation reveals partial partitioning of the Cocos-Caribbean oblique convergence into trench-parallel forearc sliver motion and less oblique thrusting on the subduction interface. The norther...
متن کاملSeismic cycle and plate margin deformation in Costa Rica : GPS observations 1994 - 1997
GPS observations in Costa Rica from 1994-1997 reveal a complex pattern of motion consistent with the superposition of seismic cycle and secular plate margin deformation. In the south, velocity vectors are consistent with motion of the Panama Block plus postseismic deformation following the 1991 Limon earthquake, and interseismic strain due to partial locking of the Middle America Trench (MAT) t...
متن کاملeld research with undergraduate students: Three models for experiential learning projects investigating active tectonics of the Nicoya Peninsula, Costa Rica
International fi eld experiences offer exceptional opportunities for effective student learning in the geosciences. Over the 10 yr period between 1998 and 2008, more than 40 undergraduate students from 14 institutions participated in fi eld research investigating active tectonics on the Nicoya Peninsula, Costa Rica. Three different project models were used: (1) a month-long summer research proj...
متن کاملMantle hydration and Cl-rich fluids in the subduction forearc
In the forearc region, aqueous fluids are released from the subducting slab at a rate depending on its thermal state. Escaping fluids tend to rise vertically unless they meet permeability barriers such as the deformed plate interface or the Moho of the overriding plate. Channeling of fluids along the plate interface and Moho may result in fluid overpressure in the oceanic crust, precipitation o...
متن کاملGeodetic and seismic constraints on some seismogenic zone processes in Costa Rica
[1] New seismic and geodetic data from Costa Rica provide insight into seismogenic zone processes in Central America, where the Cocos and Caribbean plates converge. Seismic data are from combined land and ocean bottom deployments in the Nicoya peninsula in northern Costa Rica and near the Osa peninsula in southern Costa Rica. In Nicoya, inversion of GPS data suggests two locked patches centered...
متن کامل