Deep low-frequency earthquake activity associated with the 2018 eruptions in the Kirishima volcanic complex, Japan
Deep low-frequency earthquake activity associated with the 2018 eruptions in the Kirishima volcanic complex, Japan
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DOI：
10.1186/s40623-022-01723-1
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发表时间：
2022-11-30
影响因子：
3
通讯作者：
Kato, Aitaro
中科院分区：
文献类型：
--
作者：
Kurihara, Ryo;Kato, Aitaro
在日本雾岛火山复合体中发生了深度为10-30 km的深低频（DLF）地震。在这里，我们调查了与2018年喷发相关的DLF地震活动，将这些DLF地震与2011年喷发相关的地震进行了比较，并提供了这两次喷发期间岩浆流体Ascension的推论。我们将一种新的匹配滤波器方法应用于2017-2018年期间的连续波形数据，以全面检测2018年爆发周围的DLF地震活动。这种新方法可以使用一个单一的地震台站检测微震的基础上的一个指数，计算作为产品的互信息和相关系数来衡量模板和目标波形之间的相似性。我们使用2010-2011年的波形数据进行了相同的分析，以与2011年爆发相关的DLF地震活动进行比较。在2017-2018年期间，我们在大约25公里的深度检测到75次DLF地震，而在2010-2011年期间，我们在类似深度检测到1302次DLF地震。虽然2017-2018年检测到的事件数量很少，但我们在2017年3月和7月确定了两个DLF地震活动群。2017年3月的火山群与地表的泥盆和喷流孔的出现相吻合，而2017年7月的火山群与地壳变形的开始相吻合，这表明深部岩浆库的膨胀。此外，DLF地震的发生率在2018年3月爆发后略有增加。尽管与2018年喷发相关的DLF地震发生率远低于2011年喷发，但2018年喷发期间DLF地震略有增加，这意味着2018年深部岩浆流体Ascension与浅层火山活动之间存在联系，这与2011年喷发期间观察到的情况相似。DLF地震与地表火山活动之间如此密切的时间关系表明，火山管道内的压力扰动从深部迅速传播。
Deep low-frequency (DLF) earthquakes have occurred at depths of 10-30 km in the Kirishima volcanic complex, Japan. Here, we investigate the DLF earthquake activity that was associated with the 2018 eruptions, compare these DLF earthquakes with those associated with the 2011 eruptions, and provide inferences on magmatic fluid ascension during these two eruptions. We apply a new matched-filter method to the continuous waveform data from the 2017-2018 period to comprehensively detect the DLF earthquake activity surrounding the 2018 eruptions. This new method can detect microearthquakes using a single seismic station based on an index that is computed as the product of mutual information and the correlation coefficient to measure the similarity between the template and target waveforms. We perform the same analysis using the 2010-2011 waveform data for comparison with the DLF earthquake activity associated with the 2011 eruptions. We detect 75 DLF earthquakes at approximately 25 km depth during the 2017-2018 period, whereas we detect 1302 DLF earthquakes at similar depths during the 2010-2011 period. Although the number of detected 2017-2018 events is small, we identify two swarms of DLF earthquake activity in March and July 2017. The March 2017 swarm coincides with the appearance of mud pots and jet fumaroles at the surface, and the July 2017 swarm coincides with the initiation of crustal deformation, which indicates the inflation of a deep magma reservoir. Furthermore, the occurrence rate of DLF earthquakes increased slightly after the March 2018 eruptions. Although the occurrence rate of DLF earthquakes associated with the 2018 eruptions was much lower than that associated with the 2011 eruptions, the slight increase in DLF earthquakes during the 2018 eruptions implies a connection between the deep magmatic fluid ascension and shallow volcanic unrest in 2018, which is similar to that observed during the 2011 eruptions. Such a close temporal relationship between the DLF earthquakes and surface volcanic activity suggests that the pressure disturbance within volcanic conduits propagates rapidly from depth.