Abstract—Long-period earthquakes and tremors, on a par with volcano-tectonic earthquakes, are one of two main classes of volcano-seismic activity. It is believed that long-period volcanic seismicity is associated with pressure fluctuations in the magmatic and hydrothermal systems beneath volcanoes and can therefore be used as a precursor of the impending eruptions. At the same time, the physical mechanism of the long-period seismicity is still not fully understood. In this work, we have studied the long-period earthquakes that occur at the crust–mantle boundary beneath the Klyuchevskoi volcanic group in Kamchatka in order to establish their recurrence law—the relationship between the magnitude and frequency of occurrence of the events. In the region under study, the earthquakes pertaining to this type are most numerous and characterize the state of the deep magma reservoir located at the crust–mantle boundary. The changes in the seismic regime in this part of the magmatic system can be one of the early precursors of eruptions. For a more thorough characterization of the frequency–magnitude relationship of the discussed events, we compiled a new catalog of the deep long-period earthquakes based on the matched-filter processing of continuous seismograms recorded by the network stations of the Kamchatka Branch of the Geophysical Survey of the Russian Academy of Sciences in 2011–2012. For these earthquakes, we also used a magnitude determination method that provides the estimates close to the moment magnitude scale. The analysis of the obtained catalog containing more than 40 000 events shows that the frequency–magnitude relationships of the earthquakes markedly deviate from the Gutenberg–Richter power-law distribution, probably testifying to the seismicity mechanism and peculiarities of the sources that differ from the common tectonic earthquakes. It is shown that the magnitude distribution of the deep long-period earthquakes is, rather, described by the distributions with characteristic mean values such as the normal or gamma distribution.

中文翻译：

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堪察加半岛 Klyuchevskoi 火山群下长期深地震的重现

摘要：长周期地震和地震与火山构造地震一样，是火山地震活动的两大类之一。人们认为，长期火山地震活动与火山下方岩浆和热液系统的压力波动有关，因此可以用作即将爆发的前兆。同时，对长周期地震活动的物理机制仍未完全了解。在这项工作中，我们研究了发生在堪察加半岛 Klyuchevskoi 火山群之下的壳幔边界的长周期地震，以建立它们的复发规律——事件发生的震级和频率之间的关系。在研究区域，属于这种类型的地震数量最多，并且表征了位于壳幔边界的深部岩浆储层的状态。岩浆系统这部分地震区的变化可能是喷发的早期先兆之一。为了更彻底地描述所讨论事件的频率-震级关系，我们根据地球物理勘察加分部网络站记录的连续地震图的匹配滤波处理编制了一个新的深部长周期地震目录。俄罗斯科学院2011-2012年调查。对于这些地震，我们还使用了一种震级确定方法，该方法提供了接近矩震级尺度的估计值。对获得的4万余次地震目录的分析表明，地震的频级关系明显偏离古腾堡-里希特幂律分布，可能证明了不同于普通地震的震源机制和特征。构造地震。结果表明，深部长周期地震的震级分布是由正态分布或伽马分布等具有特征均值的分布来描述的。