Teleseismic Scattered‐Wave Imaging Using a Large‐N Array in the Albuquerque Basin, New Mexico
Teleseismic Scattered‐Wave Imaging Using a Large‐N Array in the Albuquerque Basin, New Mexico
复制标题
新墨西哥州阿尔伯克基盆地使用大 N 阵列进行远震散射波成像
DOI：
10.1785/0220190146
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发表时间：
2019
影响因子：
3.3
通讯作者：
R. Aster
中科院分区：
文献类型：
--
作者：
T. Finlay;L. Worthington;B. Schmandt;N. R. Ranasinghe;S. Bilek;R. Aster
低成本连续记录无电缆自主地震仪（通常称为节点）的出现使得能够对地震波场进行密集的时空采样。我们创建虚拟源反射剖面使用P波从五个Sevilleta节点阵列实验记录在南部阿尔伯克基盆地的地震事件。盆地地质记录了一个结构复杂的历史，包括多个中生代造山作用，格兰德河裂谷延伸，并从中地壳岩浆体持续隆起。Sevilleta实验在2015年2月使用801个单通道垂直分量10 Hz地震检波器节点，以10300 m的间距部署了14天，从而使长期的区域稀疏地震仪网络更加密集。结果显示，沉积基底反射深度<5 km，并有许多次盆地结构。与大陆反射剖面联盟遗留的地壳尺度反射图像的比较表明，与裂谷盆地和上地壳的结构几何形状一致。通过将三维虚拟反射剖面与使用二维有限差分弹性波传播的合成测试进行比较，可以看出陡峭盆地边缘的P-瑞利散射很强。这些高振幅的转换在西部裂谷边缘附近的记录剖面中占主导地位，起源于洛马佩拉达断层，该断层是裂谷边界基底核断块和裂谷盆地沉积物之间的主要接触面。在近炮检距处，这些信号可能会干扰上地壳结构的解释，但它们相对较慢的时差相比，超声波P波多次波提供了清晰的时间分离，从沉积基底反射在大多数阵列。这些转换瑞利波信号的高信噪比表明，它们可能有助于限制裂谷盆地沉积物最上部101 km处的短周期（101 Hz）色散，具有很强的敏感性。
The advent of low‐cost continuously recording cable‐free autonomous seismographs, commonly referred to as nodes, enables dense spatiotemporal sampling of seismic wavefields. We create virtual source reflection profiles using P waves from five teleseismic events recorded by the Sevilleta node array experiment in the southern Albuquerque basin. The basin geology records a structurally complex history, including multiple Phanerozoic orogenies, Rio Grande rift extension, and ongoing uplift from a midcrustal magma body. The Sevilleta experiment densified the long term, regionally sparse seismograph network with 801 single channel vertical‐component 10 Hz geophone nodes deployed at ∼300 m spacing for 14 days in February 2015. Results show sediment‐basement reflections at <5 km depth and numerous sub‐basin structures. Comparisons to legacy crustal‐scale reflection images from the Consortium for Continental Reflection Profiling show agreement with structural geometries in the rift basin and upper crust. Comparisons of the teleseismic virtual reflection profiles to synthetic tests using 2D finite‐difference elastic wave propagation show strong P‐to‐Rayleigh scattering from steep basin edges. These high‐amplitude conversions dominate the record sections near the western rift margin and originate at the Loma Pelada fault, which acts as the primary contact between rift‐bounding basement‐cored fault blocks and rift basin sediments. At near offsets, these signals may interfere with interpretation of upper crustal structure, but their relatively slow moveout compared to teleseismic P‐wave multiples provides clear temporal separation from sediment‐basement reflections across most of the array. The high‐signal‐to‐noise ratio of these converted Rayleigh‐wave signals suggests that they may be useful for constraining short‐period (∼1 Hz) dispersion with strong sensitivity in the uppermost ∼1 km of the rift basin sediments.