In:
The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 105, No. 2_Supplement ( 1999-02-01), p. 1039-1039
Abstract:
For upslope propagation in an ocean environment, the place(s) where underwater acoustic field energy couples into the land seismic field is determined by the local water depth and the normal-mode composition of the acoustic energy, to first approximation. Therefore, the use of earthquake-generated T phases as natural probes of water-to-land coupling characteristics is aided by knowledge of their modal makeup. During the 1989 VAST experiment, conducted in 5000-m-deep water in the midlatitude Northeast Pacific Ocean (34.0 deg N, 140.0 deg W), the Marine Physical Lab deployed a 200-element, 3000-m-aperture vertical hydrophone array from R/P FLIP. Several earthquakes generated detectable T phases during the 11-day recording period and the modal composition of five such events, including one on land, have been determined. Because of the extended nature of the T-phase source region, the individual modes are uncorrelated, permitting an eigenanalysis of the data cross spectral matrix at a given frequency to provide approximate mode amplitude and eigenfunction information. Results indicate that for the predominant T-phase energy around 5 Hz, the first four or five modes are important, with the mode having largest amplitude often not being the lowest one. [Work supported by ONR and DSWA.]
Type of Medium:
Online Resource
ISSN:
0001-4966
,
1520-8524
Language:
English
Publisher:
Acoustical Society of America (ASA)
Publication Date:
1999
detail.hit.zdb_id:
1461063-2
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