The 'tsunami earthquake' of 1932 June 22 in Manzanillo, Mexico: Seismological study and tsunami simulations

Emile A. Okal*, José C. Borrero

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

We conduct a detailed seismological study of the large Colima, Mexico earthquake of 1932 June 3 and of its aftershocks of June 18 and 22. The latter (Event III) generated a tsunami more devastating than that of the main shock despite much smaller seismic magnitudes, thus qualifying as a so-called 'tsunami earthquake'. Relocation based on published arrival times shows that Event III took place up-dip of the main shock. The analysis of the spectral amplitude of mantle surface waves yields low-frequency moments of 24, 5.2 and 4 times 1027 dyn cm, respectively, with Event III featuring a moment growing with period, which expresses the source slowness characteristic of 'tsunami earthquakes'. This is confirmed by a deficient energy-to-moment ratio, as derived from high-frequency P waves recorded at Pasadena. Near-field hydrodynamic simulations show that the effects of the main shock's tsunami are well modelled by a standard seismic source, whereas the stronger tsunami from Event III can be modelled by rupture along a splay fault in a mechanically deficient material. All our results then fit the model for 'tsunami earthquake' aftershocks proposed for the Kuril Islands by Fukao in 1979.

Original languageEnglish (US)
Pages (from-to)1443-1459
Number of pages17
JournalGeophysical Journal International
Volume187
Issue number3
DOIs
StatePublished - Dec 2011

Keywords

  • Earthquake source observations
  • Pacific Ocean
  • Tsunamis

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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