Amplitude Source Location Method With Depth‐Dependent Scattering and Attenuation Structures: Application at Nevado del Ruiz Volcano, Colombia
Amplitude Source Location Method With Depth‐Dependent Scattering and Attenuation Structures: Application at Nevado del Ruiz Volcano, Colombia
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具有深度相关散射和衰减结构的幅度源定位方法：在哥伦比亚内瓦多德尔鲁伊斯火山的应用
DOI：
10.1029/2019jb018156
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Acevedo Rivas Alvaro Esteban
中科院分区：
文献类型：
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作者：
Kumagai Hiroyuki;Londono John Makario;Maeda Yuta;Acevedo Rivas Alvaro Esteban
振幅源定位（ASL）方法，它使用高频振幅的基础上的假设各向同性辐射的S波，与包络波形模拟的深度依赖的散射和衰减结构在Nevado del Ruiz火山，哥伦比亚进行了测试。我们的测试结果表明，当使用双层衰减模型时，估计的ASL比使用均匀衰减模型时更准确，正如以前的研究中通常所做的那样。我们将ASL方法和两层衰减模型应用于2016年在Nevado del Ruiz记录的火山构造（VT）地震、长周期（LP）和超长周期（VLP）事件以及震颤的高频（5 - 10 Hz）带。结果表明，与均匀模型相比，两层模型的ASL和VT地震震源（使用起始到达时间确定）之间的差异较小。我们确定的LP和VLP事件和震颤的ASL沿着山顶火山口下方的NW倾斜平面分布，靠近和高于具有高PtoS波速度比的区域，该区域被解释为浅岩浆储存。这个平面可能代表了沿着巴勒斯坦断层系统的薄弱地带沿着。我们的研究结果表明，LP和VLP事件和震颤发生在岩浆上升沿着断裂系统。这项研究表明，ASL方法与深度相关的衰减模型是有用的，以提高估计的火山地震信号源位置的准确性。
The amplitude source location (ASL) method, which uses high‐frequency amplitudes based on the assumption of isotropic radiation ofSwaves, was tested with envelope waveforms simulated from depth‐dependent scattering and attenuation structures at Nevado del Ruiz volcano, Colombia. Our test results indicate that estimated ASLs are more accurate when a two‐layer attenuation model is used than when a homogenous attenuation model is used, as has commonly been done in previous studies. We applied the ASL method with a two‐layer attenuation model to the high‐frequency (5‐10 Hz) band of volcanotectonic (VT) earthquakes, long‐period (LP) and very long period (VLP) events, and tremor recorded in 2016 at Nevado del Ruiz. Results indicate that the differences between ASLs and VT earthquake hypocenters (determined using onset arrival times) were smaller for a two‐layer model compared to a homogeneous model. Our determined ASLs for LP and VLP events and tremor were distributed along a NW‐dipping plane beneath the summit crater, near and above a region with highPtoSwave velocity ratios that has been interpreted as shallow magma storage. This plane may represent weak zones along the Palestina fault system. Our results suggest that LP and VLP events and tremor occur during magma ascent along the fault system. This study demonstrates that the ASL method with a depth‐dependent attenuation model is useful to improve the accuracy of estimated source locations for volcanoseismic signals.