HR: 11:30h
AN: U52A-05    [Abstracts]
TI: Multi-sensor investigation of the Sumatran Tsunami: observations and analysis of hydroacoustic, seismic, infrasonic, and tide gauge data
AU: * Bhattacharyya, J
EM: joydeep@bbn.com
AF: BBN Technologies, 1300 N. 17th Street Suite 400, Arlington, VA 22209
AU: Pulli, J
EM: jpulli@bbn.com
AF: BBN Technologies, 1300 N. 17th Street Suite 400, Arlington, VA 22209
AU: Gibson, R
EM: rgibson@bbn.com
AF: BBN Technologies, 1300 N. 17th Street Suite 400, Arlington, VA 22209
AU: Upton, Z
EM: zupton@bbn.com
AF: BBN Technologies, 1300 N. 17th Street Suite 400, Arlington, VA 22209
AB: We present an analysis of the acoustic signals from the December 26, 2004 Sumatra earthquakes, in conjunction with the seismic and tide gauge information from the event. The M9.0 mainshock and its aftershocks were recorded by a suite of seismic sensors around the globe, giving us information on its location and the source process. Recently installed sensor assets in the Indian Ocean have enabled us to study additional features of this significant event. Hydroacoustic signals were recorded by three hydrophone arrays, and the direction finding capability of these arrays allows us to examine the location, time and extent of the T-wave generation process. We detect a clear variation of the back-azimuth that is consistent with the spatial extent of the source rupture. Recordings from nearly co-located seismometers provide insights into the acoustic-to-seismic conversion process for T-waves at islands, along with the variation in signal characteristics with source size. Two separate infrasound arrays detect the atmospheric signals generated by the event, along with additional observations of the seismic surface wave and the T-phase. We will present a comparison of the signals from the mainshock, as a function of location and size, with those from aftershocks and similar events in the nearby region. Our acoustic observations compare favorably with model predictions of wave propagation in the region. For the hydroacoustic data, the azimuth, arrival time, and signal blockage characteristics, from three separate arrays, associate the onset of the signal with the mainshock and with a time extent consistent with the rupture propagation. Our analysis of the T-phase travel times suggests that the seismic-to-acoustic conversion occurs more than 100 km from the epicenter. The infrasound signal's arrival time and signal duration are consistent with both stratospheric and thermospheric propagation from a source region near the mainshock. We use the tide gauge data from stations around the Indian Ocean to identify the arrival time of the Tsunami. The acoustic and seismic signals associated with the earthquakes arrive at the remote stations significantly ahead of the Tsunami. We combine the information from the various sensors to investigate the ability of the acoustic stations to detect the Tsunami.
DE: 3099 General or miscellaneous
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4259 Ocean acoustics
DE: 4564 Tsunamis and storm surges
DE: 9340 Indian Ocean
SC: Union [U]
MN: 2005 Joint Assembly