Seismic Structure of Marine Sediments and Upper Oceanic Crust Surrounding Hawaii
Seismic Structure of Marine Sediments and Upper Oceanic Crust Surrounding Hawaii
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DOI：
10.1029/2018jb016548
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
A. Doran;G. Laske
中科院分区：
文献类型：
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作者：
A. Doran;G. Laske
我们提出的模型的压缩和剪切速度结构的海洋沉积物和上地壳周围的夏威夷群岛。这些模型是通过分析海底柔度数据和测量沉积物-基岩界面处的Ps转换相位得出的。这些数据是从连续宽带海底地震仪加速度和压力记录中估计的，这些记录是在羽流-岩石圈海底地幔实验中收集的，这是一个孔径超过1,000公里的宽带和宽带仪器的两栖阵列。我们的图像结果从联合反演的遵守和Ps延迟数据使用非线性反演方案，从而从先验约束的偏差最小化。在我们的最终模型中，沉积物厚度从50米的远端站点增加到超过1.5公里的岛屿附近。沉积物剪切速度剖面表现出较大的区域变化。虽然沉积结构占大多数的顺应性信号，我们推断剪切速度的变化在最上层基岩的± 5%的顺序。我们还要求地壳最上层的泊松比值相对较高。较低的地壳速度通常被认为是北部和西部的岛屿，但似乎没有很好地与夏威夷膨胀测深。夏威夷东北部的一个强烈低速异常区可能与莫洛凯断裂带有关。
We present models of compressional and shear velocity structure of the oceanic sediments and upper crust surrounding the Hawaiian islands. The models were derived from analysis of seafloor compliance data and measurements of Ps converted phases originating at the sediment‐bedrock interface. These data were estimated from continuous broadband ocean bottom seismometer acceleration and pressure records collected during the Plume‐Lithosphere Undersea Mantle Experiment, an amphibious array of wideband and broadband instruments with an aperture of over 1,000 km. Our images result from a joint inversion of compliance and Ps delay data using a nonlinear inversion scheme whereby deviation from a priori constraints is minimized. In our final model, sediment thickness increases from 50 m at distal sites to over 1.5 km immediately adjacent to the islands. The sedimentary shear velocity profiles exhibit large regional variations. While sedimentary structure accounts for the majority of the compliance signal, we infer variations in shear velocity in the uppermost bedrock on the order of ±5%. We also require relatively high values of Poisson's ratio in the uppermost crust. Lower crustal velocities are generally seen to the north and west of the islands but do not appear well correlated with the Hawaiian Swell bathymetry. A region of strong low velocity anomalies to the northeast of Hawaii may be associated with the Molokai fracture zone.