Preston Leiph A, Creager Kenneth C, Crosson Robert S, Brocher Thomas M, Trehu Anne M
Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA.
Science. 2003 Nov 14;302(5648):1197-200. doi: 10.1126/science.1090751.
We simultaneously invert travel times of refracted and wide-angle reflected waves for three-dimensional compressional-wave velocity structure, earthquake locations, and reflector geometry in northwest Washington state. The reflector, interpreted to be the crust-mantle boundary (Moho) of the subducting Juan de Fuca plate, separates intraslab earthquakes into two groups, permitting a new understanding of the origins of intraslab earthquakes in Cascadia. Earthquakes up-dip of the Moho's 45-kilometer depth contour occur below the reflector, in the subducted oceanic mantle, consistent with serpentinite dehydration; earthquakes located down-dip occur primarily within the subducted crust, consistent with the basalt-to-eclogite transformation.
我们同时反演了华盛顿州西北部折射波和广角反射波的走时，以获取三维压缩波速度结构、地震位置和反射体几何形状。该反射体被解释为俯冲的胡安德富卡板块的地壳 - 地幔边界（莫霍面），它将板内地震分为两组，这使得人们对卡斯卡迪亚板内地震的起源有了新的认识。在莫霍面45公里深度等值线之上倾方向的地震发生在反射体下方，即在俯冲的海洋地幔中，这与蛇纹石化脱水一致；在之下倾方向的地震主要发生在俯冲地壳内，这与玄武岩向榴辉岩的转变一致。
