The deficient T waves of tsunami earthquakes

Emile A. Okal, Pierre Jean Alasset, Olivier Hyvernaud, François Schindelé

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

We develop an algorithm quantifying the energy flux of T phases recorded at island stations following major teleseismic events, which we further scale by the seismic moment Mo of the earthquake, to define a T-phase efficiency, Γ. We apply this concept to a set of six recognized tsunami earthquakes, which generated tsunamis larger than expected from their conventional seismic waves. Through comparison with nearby reference events the T waves of which were recorded at the same sites, we find that the tsunami earthquakes exhibit a deficiency in Γ ranging from 1.5 to 2.5 orders of magnitude. This result settles a 50 yr old controversy on the possible correlation between T-wave generation and tsunami genesis. The deficient character of the T waves from tsunami earthquakes readily supports the proposed model of an exceedingly slow rupture velocity for this class of events, and the close examination of T wave trains supports the concept of a jerky rupture in at least two cases. The computation of Γ is straightforward in real time, and could become a valuable contribution to real-time tsunami warning in the far field.

Original languageEnglish (US)
Pages (from-to)416-432
Number of pages17
JournalGeophysical Journal International
Volume152
Issue number2
DOIs
StatePublished - Feb 2003

Keywords

  • Hydroacoustics
  • Slow earthquakes
  • T waves
  • Tsunamis

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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