Global observation of vertical‐CLVD earthquakes at active volcanoes
Global observation of vertical‐CLVD earthquakes at active volcanoes
复制标题
活火山垂直-CLVD地震的全球观测
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
G. Ekström
中科院分区：
文献类型：
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作者：
A. Shuler;M. Nettles;G. Ekström
一些最大和最异常的火山地震具有非双偶震源机制。在这里，我们研究了火山不稳定与以垂直张力或压力轴为主导的非双偶地震之间的联系，即垂直补偿-线性-矢量-偶极子（垂直- CLVD）地震。我们从全球质心矩张量项目的标准波表和面波表中确定了313次目标地震的震源机制，并确定了86次位于火山附近的浅层4.3≤MW≤5.8垂直- CLVD地震，这些地震在过去~100年里爆发过。大多数垂直CLVD地震发生在与玄武岩-安山岩层状火山或海底火山相关的俯冲带，尽管垂直CLVD地震也位于大陆裂谷和热点火山活动区域。垂直- CLVD地震与附近火山的许多类型的已证实或怀疑的喷发活动有关，包括火山地震群、喷涌和爆炸性喷发以及火山口崩塌。在研究的所有垂直- CLVD地震中，大约70%发生在附近火山有记录的火山不稳定时期。考虑到火山不稳定被低估，大多数靠近活火山的浅层垂直- CLVD地震可能与岩浆迁移或喷发过程有关。以垂直压力轴为主导的垂直- CLVD地震通常发生在火山喷发之后，而以垂直张力轴为主导的垂直- CLVD地震通常发生在火山不稳定开始之前。这些事件的发生可能有助于识别最近爆发的火山和将来可能爆发的火山。
Some of the largest and most anomalous volcanic earthquakes have non‐double‐couple focal mechanisms. Here, we investigate the link between volcanic unrest and the occurrence of non‐double‐couple earthquakes with dominant vertical tension or pressure axes, known as vertical compensated‐linear‐vector‐dipole (vertical‐CLVD) earthquakes. We determine focal mechanisms for 313 target earthquakes from the standard and surface wave catalogs of the Global Centroid Moment Tensor Project and identify 86 shallow 4.3 ≤ MW ≤ 5.8 vertical‐CLVD earthquakes located near volcanoes that have erupted in the last ~100 years. The majority of vertical‐CLVD earthquakes occur in subduction zones in association with basaltic‐to‐andesitic stratovolcanoes or submarine volcanoes, although vertical‐CLVD earthquakes are also located in continental rifts and in regions of hot spot volcanism. Vertical‐CLVD earthquakes are associated with many types of confirmed or suspected eruptive activity at nearby volcanoes, including volcanic earthquake swarms as well as effusive and explosive eruptions and caldera collapse. Approximately 70% of all vertical‐CLVD earthquakes studied occur during episodes of documented volcanic unrest at a nearby volcano. Given that volcanic unrest is underreported, most shallow vertical‐CLVD earthquakes near active volcanoes are likely related to magma migration or eruption processes. Vertical‐CLVD earthquakes with dominant vertical pressure axes generally occur after volcanic eruptions, whereas vertical‐CLVD earthquakes with dominant vertical tension axes generally occur before the start of volcanic unrest. The occurrence of these events may be useful for identifying volcanoes that have recently erupted and those that are likely to erupt in the future.