The seismic source parameters of the 1991 Costa Rica aftershock sequence: evidence for a transcurrent plate boundary

Fan Guangwei Fan, S. L. Beck, T. C. Wallace

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

The April 22, 1991, Valle de la Estrella, Costa Rica earthquake (Ms = 7.6) was a back-arc thrusting event associated with the underthrusting of the Caribbean plate beneath Central America. A network of three PASSCAL-type, portable instruments was deployed to monitor the aftershock activity in southern Costa Rica 2 to 6 weeks after the main shock. The focal mechanisms are generally in good agreement with P wave first-motion fault plane solutions determined from a local short-period network. The aftershocks show a clear spatial segmentation based on focal mechanism type. Most aftershocks near or southeast of the main shock were thrusting events with focal mechanisms similar to the main shock. In contrast, a cluster of aftershocks northwest of the main shock showed dominantly left-lateral, strike-slip motion on a northeasterly striking nodal plane. -from Authors

Original languageEnglish (US)
Pages (from-to)15,759-15,778
JournalJournal of Geophysical Research
Volume98
Issue numberB9
StatePublished - Jan 1 1993

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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