SASSIER22: Full-waveform tomography of the eastern Indonesian region that includes surface topography and the fluid ocean
SASSIER22: Full-waveform tomography of the eastern Indonesian region that includes surface topography and the fluid ocean
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SASSIER22：印度尼西亚东部地区的全波形断层扫描，包括表面地形和流体海洋
DOI：
10.1002/essoar.10511562.1
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Wehner D
中科院分区：
文献类型：
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作者：
Wehner D
我们提出了一个新的3-D地震结构模型的印尼东部地区及其周围地区的全波形反演（FWI），利用地震数据过滤在15 - 150秒之间的周期。SASSY 21-东南亚最近的3-D FWI层析模型-被用作起始模型，我们的研究区域的特点是特别好的数据覆盖范围，这有利于更精细的图像。我们使用的频谱元素求解器Salvus来确定完整的3-D波场，占流体海洋明确通过求解耦合系统的声波和弹性波方程。这在计算上更昂贵，但允许模拟水层内的地震波，这对于周期≤ 20 s变得很重要。我们调查路径依赖的影响，表面高程（地形和测深）和流体海洋合成波形，并比较我们的最终模型与常用的海洋负载近似得到的层析结果。此外，我们强调了我们的最终模型SASSIER 22的一些关键特征-经过34次L-BFGS迭代，揭示了地幔过渡区的详细异常，包括沿菲律宾海沟南部沿着的会聚双俯冲带，这在初始模型中并不明显。一个更详细的照明板下的北苏拉威西海沟揭示了一个明显的积极的波速异常下降到200公里的深度，符合地震活动的最大深度，和一个更分散，但asepressive积极的波速异常，继续到410公里的不连续。
We present a new 3-D seismic structural model of the eastern Indonesian region and its surroundings from full-waveform inversion (FWI) that exploits seismic data filtered at periods between 15 - 150 s. SASSY21 - a recent 3-D FWI tomographic model of Southeast Asia - is used as a starting model, and our study region is characterized by particularly good data coverage, which facilitates a more refined image. We use the spectral-element solver Salvus to determine the full 3-D wavefield, accounting for the fluid ocean explicitly by solving a coupled system of acoustic and elastic wave equations. This is computationally more expensive but allows seismic waves within the water layer to be simulated, which becomes important for periods ≤ 20 s. We investigate path-dependent effects of surface elevation (topography and bathymetry) and the fluid ocean on synthetic waveforms, and compare our final model to the tomographic result obtained with the frequently used ocean loading approximation. Furthermore, we highlight some of the key features of our final model - SASSIER22 - after 34 L-BFGS iterations, which reveals detailed anomalies down to the mantle transition zone, including a convergent double-subduction zone along the southern segment of the Philippine Trench, which was not evident in the starting model. A more detailed illumination of the slab beneath the North Sulawesi Trench reveals a pronounced positive wavespeed anomaly down to 200 km depth, consistent with the maximum depth of seismicity, and a more diffuse but aseismic positive wavespeed anomaly that continues to the 410 km discontinuity.