HR: 08:45h
AN: OS31A-04    [PDF]
TI: T waves from the 1998 Papua New Guinea earthquake and its aftershocks: Timing the tsunamigenic slump
AU: Synolakis, C E
EM: costas@usc.edu
AF: Univ. Southern Calif., Dept. of Civil Engineering, Los Angeles, CA 90089 United States
AU: * Okal, E A
EM: emile@earth.nwu.edu
AF: Northwestern Univ., Locy Hall, Evanston, IL 60208 United States
AB: 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 (m sub b = 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-km**3 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 run-up; timing) could not be explained by a dislocation model.
DE: 4259 Ocean acoustics
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting