3D Seismic Velocity Models for Alaska from Joint Tomographic Inversion of Body-Wave and Surface-Wave Data
3D Seismic Velocity Models for Alaska from Joint Tomographic Inversion of Body-Wave and Surface-Wave Data
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DOI：
10.1785/0220200214
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发表时间：
2020-11
影响因子：
3.3
通讯作者：
A. Nayak;D. Eberhart‐Phillips;N. Ruppert;H. Fang;Melissa M. Moore;C. Tape;D. Christensen;G. Abers;C. Thurber
中科院分区：
文献类型：
--
作者：
A. Nayak;D. Eberhart‐Phillips;N. Ruppert;H. Fang;Melissa M. Moore;C. Tape;D. Christensen;G. Abers;C. Thurber
我们使用两种不同的方法，通过体波和环境噪声派生的面波数据的联合反演，提出了两个新的阿拉斯加地震速度模型。我们的工作利用了最近许多临时地震台网的数据，包括阿拉斯加可移动地震台阵、南阿拉斯加岩石圈和地幔观测网以及阿拉斯加两栖社区地震实验的陆上台站。第一个模型主要覆盖阿拉斯加中南部，并使用体波到达时间，瑞利波群速度图考虑了它们与周期相关的横向敏感性。第二个模型由体波到达时间和面波相位走时直接反演而成，覆盖了整个阿拉斯加州。这两个模型提供了∼0-100公里深度的三维纵波速度(Vp)和横波速度(VS)信息。这两种模式既有许多相似之处，也有不同之处。第一个模型根据地震速度和波速比提供了高速俯冲板块和低速地幔楔体的清晰图像。全州范围的模型提供了许多特征的更清晰的图像，如沉积盆地，德纳利火山缺口下的地幔楔形中的高速异常，布鲁克斯山脉下的下地壳中的低VP，以及兰格尔火山田下的雅库塔特地体东缘的低速。从同时重新定位的地震中，我们还发现阿拉斯加南部下方俯冲太平洋板块的深度似乎比以前的模型更深。
We present two new seismic velocity models for Alaska from joint inversions of body-wave and ambient-noise-derived surface-wave data, using two different methods. Our work takes advantage of data from many recent temporary seismic networks, including the Incorporated Research Institutions for Seismology Alaska Transportable Array, Southern Alaska Lithosphere and Mantle Observation Network, and onshore stations of the Alaska Amphibious Community Seismic Experiment. The first model primarily covers south-central Alaska and uses body-wave arrival times with Rayleigh-wave group-velocity maps accounting for their period-dependent lateral sensitivity. The second model results from direct inversion of body-wave arrival times and surface-wave phase travel times, and covers the entire state of Alaska. The two models provide 3D compressional- (VP) and shear-wave velocity (VS) information at depths ∼0–100 km. There are many similarities as well as differences between the two models. The first model provides a clear image of the high-velocity subducting plate and the low-velocity mantle wedge, in terms of the seismic velocities and the VP/VS ratio. The statewide model provides clearer images of many features such as sedimentary basins, a high-velocity anomaly in the mantle wedge under the Denali volcanic gap, low VP in the lower crust under Brooks Range, and low velocities at the eastern edge of Yakutat terrane under the Wrangell volcanic field. From simultaneously relocated earthquakes, we also find that the depth to the subducting Pacific plate beneath southern Alaska appears to be deeper than previous models.