SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography
SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography
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SASSY21：东南亚岩石圈和下伏地幔的 3D 地震结构模型，来自多尺度伴随波形断层扫描
DOI：
10.1002/essoar.10507767.1
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发表时间：
2021
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
我们提出了东南亚岩石圈和下伏地幔的第一个大陆尺度地震模型，该模型是通过伴随波形层析成像（通常称为全波形反演或FWI）获得的，使用的地震数据在20到150 s的周期内进行滤波。基于从13,000个独特的源-接收器对收集的>3,000小时的分析波形数据，我们通过从一维参考模型开始的迭代非线性反演来成像各向同性P波速度，径向各向异性S波速度和密度。在每次迭代中，通过滞弹性地球确定完整的三维波场，并考虑地形、水深和海洋载荷的影响。我们的数据选择旨在通过单独考虑体波到达来最大限度地提高对深部结构的敏感性。SASSY 21是我们在7个周期带上进行87次迭代后的最终模型，能够解释来自未包括在反演中的事件和接收器的真振幅数据。通过对Hessian矢量积的分析，估计了反演参数之间的权衡。SASSY 21揭示了下至地幔过渡带的详细异常，包括多个俯冲带。最突出的特征是（印度-）澳大利亚板块下降到印度尼西亚之下，这是一个连续的板沿着180°弯曲的班达弧。层析成像证实了坦博拉山下方板块中存在一个洞，并在婆罗洲北方下方定位了一个高S波速度区，该区域可能与中新世中晚期的俯冲终止有关。在婆罗洲东海岸下面还发现了一个以前未被发现的特征，这可能是苏拉威西形成后俯冲过程、分层或俯冲的标志。
We present the first continental‐scale seismic model of the lithosphere and underlying mantle beneath Southeast Asia obtained from adjoint waveform tomography (often referred to as full‐waveform inversion or FWI), using seismic data filtered at periods from 20 to 150 s. Based on >3,000 hr of analyzed waveform data gathered from ∼13,000 unique source‐receiver pairs, we image isotropicP‐wave velocity, radially anisotropicS‐wave velocity and density via an iterative non‐linear inversion that begins from a 1‐D reference model. At each iteration, the full 3‐D wavefield is determined through an anelastic Earth, accommodating effects of topography, bathymetry and ocean load. Our data selection aims to maximize sensitivity to deep structure by accounting for body wave arrivals separately.SASSY21, our final model after 87 iterations across seven period bands, is able to explain true‐amplitude data from events and receivers not included in the inversion. The trade‐off between inversion parameters is estimated through an analysis of the Hessian‐vector product.SASSY21reveals detailed anomalies down to the mantle transition zone, including multiple subduction zones. The most prominent feature is the (Indo‐)Australian plate descending beneath Indonesia, which is imaged as one continuous slab along the 180° curvature of the Banda Arc. The tomography confirms the existence of a hole in the slab beneath Mount Tambora and locates a highS‐wave velocity zone beneath northern Borneo that may be associated with subduction termination in the mid‐late Miocene. A previously undiscovered feature beneath the east coast of Borneo is also revealed, which may be a signature of post‐subduction processes, delamination or underthrusting from the formation of Sulawesi.