High-frequency Po/So guided waves in the oceanic lithosphere: II―heterogeneity and attenuation
High-frequency Po/So guided waves in the oceanic lithosphere: II―heterogeneity and attenuation
复制标题
大洋岩石圈高频Po/So导波：II—非均质性和衰减
DOI：
10.1093/gji/ggu286
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
T. Fuirumura and Y.Zhao
中科院分区：
文献类型：
--
作者：
Kennett;B.L.N.;T. Fuirumura and Y.Zhao
在西太平洋，高频率的地震能量被带到离震源很远的地方。具有地幔岩石圈特征地震速度的PoandSphases具有复杂和拉长的波形，可以用随机非均匀性模型很好地解释。然而，在太平洋海盆东部，等效路径显示出弱的或缺失的So。这种导能一旦建立，就很难通过单纯的构造作用消除。即使岩石圈厚度的急剧变化或断裂带的复杂过渡也只会减弱地幔输送的波列，但Po和Sormain是不同的。相比之下，衰减的影响要严重得多，并且可以导致在通过几百公里后将相位抑制到低于噪声水平。因此，整个太平洋的PoandSo的不同特征可以通过较热区域（如扩张脊和弧后区域）的增强衰减与热状态直接相关。
In the western Pacific, high-frequency seismic energy is carried to very great distances from the source. ThePoandSophases with observed seismic velocities characteristic of the mantle lithosphere have complex and elongated waveforms that are well explained by a model of stochastic heterogeneity. However, in the eastern part of the Pacific Basin equivalent paths show mutedPoand weak, or missing,So. Once established, it is hard to eliminate such guidedPoandSoenergy in the mantle lithosphere by purely structural effects. Even sharp changes in lithospheric thickness or complex transitions at fracture zones only weaken the mantle ducted wave trains, butPoandSoremain distinct. In contrast, the effect of attenuation is much more severe and can lead to suppression of theSophase to below the noise level after passage of a few hundred kilometres. The differing characteristics ofPoandSoacross the Pacific can therefore be related directly to the thermal state via the enhanced attenuation in hotter regions, such as the spreading ridges and backarc regions.