Fault‐Associated Magma Conduits Beneath Volcán de Colima Revealed by Seismic Velocity and Attenuation Tomography Studies
Fault‐Associated Magma Conduits Beneath Volcán de Colima Revealed by Seismic Velocity and Attenuation Tomography Studies
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地震速度和衰减断层扫描研究揭示了科利马火山下方与断层相关的岩浆管道
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发表时间：
2019
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影响因子：
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通讯作者：
Mamdoh S. Alajmi
中科院分区：
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作者：
I. Sychev;I. Koulakov;I. Egorushkin;S. Zhuravlev;M. West;S. El Khrepy;N. Al‐Arifi;Mamdoh S. Alajmi
我们展示了利用科利马火山复合体 (CVC) 区域地震速度和衰减进行的层析成像研究的结果。我们的数据集包括科利马地区 CODEX 网络临时地震台和区域测绘里维拉俯冲带 (MARS) 网络的一些台站记录的当地地震体波，这两个地震台均于 2006 年至 2008 年部署。我们获得了 CVC 区域下方地壳中地震速度和衰减的三维分布。在浅层，我们观察到 CVC 以南有一个巨大的负异常，与中科利马地堑的位置一致。这种异常可能代表碎片雪崩沉积物，以及为目前活跃的科利马火山喷发提供水源的浅层岩浆库。相比之下，内华达科利马火山大厦由坚硬的火成岩构成，与浅层的高速和低衰减异常有关。在更深的剖面中，具有高Vp/Vs、低Vs和高S波衰减的主要异常对应于区域性塔马祖拉断层的位置。由于这代表了地壳的机械弱化区域，因此它可能形成供给 CVC 的通道。速度和衰减模型都表明，与断层相关的管道将岩浆从地幔穿过下地壳输送到 15 公里的深度。然后，一小部分岩浆可能会继续上升，在 CVC 南翼下方形成浅层储层。
We present the results of tomographic studies using seismic velocity and attenuation in the area of the Colima Volcanic complex (CVC). Our dataset comprises body waves from local earthquakes recorded by the temporary seismic stations of the CODEX network in the Colima area and a few stations of the regional Mapping the Rivera Subduction Zone (MARS) networks, both deployed in 2006–2008. We obtain three‐dimensional distributions of seismic velocities and attenuation in the crust beneath the CVC area. At shallow depths, we observe a large negative anomaly to the south of CVC, coinciding with the location of the Central Colima Graben. This anomaly may represent debris avalanche deposits, as well as shallow magma reservoirs feeding the eruptions of the presently active Volcán de Colima. In contrast, the volcano edifice of Nevado de Colima, which is built of rigid igneous rocks, is associated with high‐velocity and low‐attenuation anomalies at shallow depths. In the deeper section, a major anomaly with high Vp/Vs, low Vs, and high S wave attenuation corresponds to the location of the regional Tamazula fault. As this represents a mechanically weakened zone of the crust, it may form the pathway that feeds CVC. Both velocity and attenuation models show that the fault‐associated conduit brought magma from the mantle through the lower crust to a depth of 15 km. Then, a light fraction of magma may continue to ascend, forming shallow reservoirs beneath the southern flank of CVC.