Quantification of hydrophone records of the 2004 Sumatra Tsunami

Emile A. Okal*, Jacques Talandier, Dominique Reymond

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The 2004 Sumatra-Andaman tsunami was recorded by hydrophones of the International Monitoring System at Site H08 near Diego Garcia, notably in frequency bands extending outside the range of the Shallow Water Approximation. Despite the severe high-pass filtering involved in this instrumentation, we show that the spectral amplitudes recovered around T = 87 s can be successfully explained by generation from the seismic source, in the framework of the normal mode theory of tsunami excitation. At the lower frequencies characteristic of more conventional tsunami waves (800 to 3200 s), the signal is probably present in the hydrophone records, but reliable deconvolution of its spectral amplitude is precluded by the fact that the instrumental filters lowered the tsunami signal to the level of resolution of the instrument digitizer. In the context of distant tsunami warning, hydrophone records could provide useful insight into high-frequency tsunami components, and even at lower, more conventional, frequencies, provided that an unfiltered channel could be recorded routinely.

Original languageEnglish (US)
Pages (from-to)309-323
Number of pages15
JournalPure and Applied Geophysics
Volume164
Issue number2-3
DOIs
StatePublished - Mar 2007

Funding

This research was supported by the National Science Foundation, under Grant CMS-03-01054 and by Commissariat à 1’Energie Atomique. We thank Roger Bowman for information on the frequency responses at H08. Several figures were drafted using the GMT software (WESSEL and SMITH, 1991).

Keywords

  • Hydroacoustics
  • Normal mode theory
  • T waves
  • Tsunami

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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