Abstract
Gorely is one of the most active volcanoes in Kamchatka with a rich magmatic and eruptive history reflected in its composite structure. In 2013–2014, a temporary network of 20 seismic stations was installed on Gorely for one year. During the four months of its high degassing rate, seismic activity was mostly expressed in the form of a long-period (LP) seismic tremor. In this study, we have developed a workflow based on the combination of back-projection (BP), cluster analysis, and matched-filter (MF) methods. By applying it to continuous seismic records for the study period, we were able to identify discrete LP events within the tremor sequence automatically and individually investigate their properties. A catalog obtained using the BP detection algorithm consist of 1741 high-energy events. Cluster analysis revealed that the entire variety of LP earthquakes in this catalog could be grouped into five families, which are sequentially organized in time. Utilizing templates of these families in the MF search resulted in the complementary catalog of 80,615 low-energy events. The long-term occurrence of highly repetitive LP events in the same location may correspond to resonating conduits behaving in response to the high-pressure gases flowing from the decompressed magma chamber up to the volcano’s crater.
Highlights
Processes in active magma systems can set in motion different types of seismic sources occurring either through abrupt fractures of rocks, or oscillations of magma containing reservoirs, or as a combination of these two processes [1,2]
In the scope of this study, we investigate the LP earthquakes beneath the active Gorely Volcano in Kamchatka
The primary purpose of this study is to further investigate the processes in the magmatic system beneath the Gorely volcano during the period of intense degassing activity in late 2013
Summary
Processes in active magma systems can set in motion different types of seismic sources occurring either through abrupt fractures of rocks, or oscillations of magma containing reservoirs, or as a combination of these two processes [1,2]. In contrast to previously performed tomography study, here we use the continuous seismic records of the temporary network to study the distributions and properties of LP earthquakes beneath Gorely Both the massive size of the dataset and the high expected occurrence-rate of these events urged us to develop the following three-step workflow: (1) identification of the most potent LP events by the back-projection detection technique, (2) cluster analysis of obtained catalog in order to group events with similar waveforms into several families, each represented by corresponding master event, (3) extension of the catalog to low-energy LP events by matched-filter detection technique using waveforms of the master events as a template. We provide a possible interpretation of the resulting LP seismicity properties in terms of volcanic processes
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