Abstract
T waves recorded at hydrophone and seismic stations following the Papua New Guinea earthquake of 17 July 1998 and its aftershocks show that a small event at 09:02 GMT featured source properties incompatible with an elastic dislocation of appropriate body-wave magnitude (mb = 4.4). These include an exceptional duration (47 s at the Wake Island hydrophone station WK31), a spectrum rich in high frequencies (7 to 12 Hz), and a generally low spectral amplitude. These characteristics can be explained by the model of an underwater slump, accelerating from a standstill and eventually slowing down. The relocation of the 09:02 event is compatible with its location within an amphitheater inside which shipboard cruises in 1998 and 1999 documented the presence of a 4 - km3 geologically fresh slump. We propose that the slump took place at 09:02 on 17 July 1998, i.e., 13 minutes after the mainshock, and that it generated the locally catastrophic tsunami, whose properties (amplitude and distribution of runup; timing) could not be explained by a dislocation model.
Original language | English (US) |
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Pages (from-to) | 1843-1863 |
Number of pages | 21 |
Journal | Pure and Applied Geophysics |
Volume | 160 |
Issue number | 10-11 |
DOIs | |
State | Published - Oct 2003 |
Keywords
- Landslides
- T waves
- Tsunamis
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology