Open AccessThe deficient T waves of tsunami earthquakes
Author(s) -
Okal Emile A.,
Alasset PierreJean,
Hyvernaud Olivier,
Schindelé François
Publication year - 2003
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.1365-246x.2003.01853.x
Subject(s) - seismology , geology , tsunami earthquake , tsunami wave , magnitude (astronomy) , seismic wave , seismic energy , geophysics , physics , astronomy
SUMMARY 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 M 0 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.