High‐frequency seismic attenuation of oceanic P and S waves in the western Pacific
High‐frequency seismic attenuation of oceanic P and S waves in the western Pacific
复制标题
西太平洋海洋纵波和纵波的高频地震衰减
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
D. Walker
中科院分区：
文献类型：
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作者：
R. Butler;C. Mccreery;L. Frazer;D. Walker
对千岛群岛地震的海洋P和S数据进行了分析，该地震发生在威克岛附近1500公里长的海底水听器阵列部署的趋势上，对西太平洋高频地震衰减产生了限制。对群速度在8.2 ~ 3.0 km/s之间、频率在2.5 ~ 22.5 Hz之间时的空间衰减和Q值进行了测定。在所有频率上，海洋P比海洋S衰减更大，这表明岩石圈中存在显著的整体衰减，或者海洋P以泄漏模式传播。海洋P和S的表观衰减与距离有关，在30°Δ以外的衰减较小。海洋P的表观Q随频率增加，如Q ~ ƒ0.7，从2.5 Hz的约300增加到17.5 Hz的1500。海洋S的表观Q随频率Q ~ ƒ1.1的增加而增加，从2.5 Hz时的约400增加到22.5 Hz时的3000。
Analyses of oceanic P and S data from an earthquake in the Kuril Islands which occurred along the trend of a 1500-km-long ocean bottom hydrophone array deployment near Wake Island have yielded constraints on high-frequency seismic attenuation in the western Pacific. Spatial attenuation and Q were determined for group velocities between 8.2 and 3.0 km/s and for frequencies between 2.5 and 22.5 Hz. There is greater attenuation of oceanic P than oceanic S at all frequencies suggesting either the presence of significant bulk attenuation in the lithosphere or that oceanic P propagates as a leaky mode. The apparent attenuation of oceanic P and S is distance-dependent, with lower attenuation beyond 30° Δ. The apparent Q of oceanic P increases with frequency as Q ∼ ƒ0.7, from about 300 at 2.5 Hz to 1500 at 17.5 Hz. The apparent Q of oceanic S increases with frequency as Q ∼ ƒ1.1, from about 400 at 2.5 Hz to 3000 at 22.5 Hz.