Low stress drop earthquakes in the rupture zone of the 1992 Nicaragua tsunami earthquake. Issue 19 (11th October 2016)

• Record Type: Journal Article
• Authors: Bilek, Susan L.; Rotman, Holly M. M.; Phillips, W. Scott
• Is Part Of: Geophysical research letters. Volume 43:Issue 19(2016)
• Page Start: 10, 180
• Page End: 10, 188
• Publication Date: 2016-10-11
• Subjects: tsunami earthquake -- stress drop -- Nicaragua; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL070409
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Tsunami earthquakes, events that generate larger than expected tsunami and are deficient in high‐frequency seismic radiation, are rare but hazardous to coastal populations. One model for these events is shallow rupture through low‐strength materials. We calculate seismic moment, corner frequency, and stress drop for 216 earthquakes (2.1 < Mw < 4.7, November 2005 to June 2006) within and external to the 1992 Nicaragua tsunami earthquake rupture zone to test the hypothesis that differences in fault zone properties defined the limits of the 1992 tsunami rupture zone and continue to produce spatial variations in earthquake source properties. Mean stress drop of events within the rupture area is 1.2 MPa, and 5.5 MPa for events just outside of the rupture zone, with similar magnitude earthquakes in each group. Our results demonstrate different source parameter characteristics for microseismicity in the region of a past tsunami earthquake. Key Points: Earthquake source parameters presented for 216 earthquakes along Pacific coast of Nicaragua and Costa Rica Stress drop is lower for earthquakes within the 1992 tsunami earthquake rupture zone Results suggest that microseismicity can provide indication of anomalous rupture zones