Arctic abyssalTphases: Coupling seismic energy to the ocean sound channel via under-ice scattering
作者:
Ruth Eta Keenan,
Lynn Renee Lineback Merriam,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1991)
卷期:
Volume 89,
issue 3
页码: 1128-1133
ISSN:0001-4966
年代: 1991
DOI:10.1121/1.400648
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Earthquakes along the mid-arctic ridge radiate earthborne compressional and shear waves that couple into the waterborne arctic acoustic channel and propagate asTphases. TheT-phase energy is transmitted above the epicenter through the seafloor at near-vertical angles. Scattering from the ice surface couples some of this energy into waterborne angles. At 5 Hz, the coupled energy is about 40 dB down from the incident levels, and at 15 Hz it is about 30 dB down. Scattering accounts for the characteristic spectral shape of the abyssalTphase that is more energetic at 15 Hz than 5 Hz. SeveralT-phase arrivals were recorded on hydrophones during the FRAM II experiment. From the measured acoustic levels, a transmission loss prediction between source and receiver, and the scattering conversion losses, the microearthquake acoustic source level in the water column is estimated to be about 250 dBre 1 μPa2-m/Hzat 5 Hz and 235 dBre 1 μPa2-m/Hzat 15 Hz. These levels lead to a crustal attenuation estimate of 0.52 dB/km at 5 Hz, which is consistent with FRAM II refraction measurements.
点击下载:
PDF
(948KB)
返 回