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GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 20, 1977, doi:10.1029/2002GL015409, 2002

Along-strike variability in the seismogenic zone below Nicoya Peninsula, Costa Rica

A. V. Newman

Department of Earth Sciences, University of California Santa Cruz, Santa Cruz, California, USA


S. Y. Schwartz

Department of Earth Sciences, University of California Santa Cruz, Santa Cruz, California, USA


V. Gonzalez

Observatorio Vulcanológico y Sismológico de Costa Rica, la Universidad Nacional de Costa Rica, Heredia, Costa Rica


H. R. DeShon

Department of Earth Sciences, University of California Santa Cruz, Santa Cruz, California, USA


J. M. Protti

Observatorio Vulcanológico y Sismológico de Costa Rica, la Universidad Nacional de Costa Rica, Heredia, Costa Rica


L. M. Dorman

Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA


Abstract

At the subduction zone in northwestern Costa Rica, the seismogenic zone lies directly beneath the Nicoya Peninsula, allowing for near source seismic studies of earthquake activity. We located 650 earthquakes along the seismogenic plate interface using a dense seismic network in the vicinity of the Nicoya Peninsula. Using these data we constrained the updip limit of the seismogenic zone there and found a transition in depth, 10 km in the south to 20 km in the north, that occurs where the subducting oceanic crust changes from warmer Cocos-Nazca Spreading center (CNS) origin to colder East Pacific Rise (EPR) origin. We argue that the temperature of the incoming oceanic crust controls the seismogenic updip limit beneath Nicoya, Costa Rica; subducting colder oceanic crust deepens the seismogenic updip limit.

Published 25 October 2002.

Index Terms: 3015 Marine Geology and Geophysics: Heat flow (benthic) and hydrothermal processes; 7209 Seismology: Earthquake dynamics and mechanics; 7220 Seismology: Oceanic crust; 7230 Seismology: Seismicity and seismotectonics.

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Citation: Newman, A. V., S. Y. Schwartz, V. Gonzalez, H. R. DeShon, J. M. Protti, and L. M. Dorman (2002), Along-strike variability in the seismogenic zone below Nicoya Peninsula, Costa Rica, Geophys. Res. Lett., 29(20), 1977, doi:10.1029/2002GL015409.