Imaging a slow bilateral rupture with broadband seismic waves: The September 2, 1992 Nicaraguan tsunami earthquake

Aaron A. Velasco, Charles J. Ammon, Thorne Lay, Jiajun Zhang

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27 Scopus citations

Abstract

The spatio‐temporal rupture history of the September 2, 1992 Nicaragua tsunami earthquake (Ms=7.2; Mw=7.6) is analyzed using long‐period (157–288 s) Rayleigh and Love wave spectral inversions and an empirical Green function analysis of very broadband (10–250 s) body and surface waves. The event has a rupture duration exceeding 110 s with a slow (0.6–2.3 km/s) rupture velocity, and involves shallow dipping (6°–10°) thrust faulting at a shallow depth (≤ 10 km), with the latter being primarily responsible for the strong tsunami excitation. Two subevents dominate the source radiation, resulting from a slow asymmetric bilateral, 100–160 km long rupture. Long‐period surface wave directivity reveals a predominant rupture azimuth of 140° ± 30°, consistent with asymmetric extension of the bilateral rupture at an azimuth of 125° ± 30° resolved by the source time function analysis. An inverse Radon transform of the source time functions confirms the asymmetric bilateral rupture characteristics.

Original languageEnglish (US)
Pages (from-to)2629-2632
Number of pages4
JournalGeophysical Research Letters
Volume21
Issue number24
DOIs
StatePublished - Dec 1 1994

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

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