Earthquake characteristics before eruptions of Japan's Ontake volcano in 2007 and 2014

Abstract

We detect earthquakes associated with Japan's Ontake eruptions in 2007 and 2014 using the match‐and‐locate method. Thirty‐seven times more events (4949) than the Japan Meteorological Agency (JMA) catalog (133) and 30 times more events (1880) than the JMA catalog (62) are detected during the eruptions of 2007 and 2014, respectively. The detected earthquakes are further classified into three different types: long‐period (LP) events, LP‐associated events, and volcano‐tectonic (VT) earthquakes. Both LP and LP‐associated events are observed in the two eruptions. We suggest that the observed intense seismicity before both eruptions indicates the rewaking of Ontake volcano and might be used to predict its impending eruption in the long term. The temporal persistence and spatial concentration of LP and LP‐associated events may be used to predict the eventual eruption and eruption location, and the maximum magnitude of the LP events may be used as an indicator of eruption magnitude.

Special issue “The phreatic eruption of Mt. Ontake volcano in 2014”

“…Kato et al (2015) and Zhang and Wen (2015) provide detailed descriptions of the hypocenters associated with the eruption. Maeda et al (2015) infer crack opening immediately before the eruption.…”

“…Ontake (1979, 1991, 2007, 2014 reflects repeated pressurization and breaching of the shallow hydrothermal system. In the absence of seismicity and associated fracturing, there is a fairly universal tendency for permeability to decrease due to mineral precipitation and other hydrothermal-alteration processes (Gleeson and Ingebritsen 2016).…”

“…The authors emphasize that hypocenter migration immediately before the eruption may reflect the movement of hydrothermal fluids to the surface. Zhang and Wen (2015) (Geophysical Research Letters) apply the match-and-locate method to detect and precisely locate seismic activity associated with the 2007 and 2014 eruptions. The results for 2007 show less variation in the epicenter location than those associated with the 2014 eruption, consistent with the results of Kato et al (2015).…”

Spatiotemporal Distribution of Microearthquakes and Implications Around the Seismic Gap Between the Wenchuan and Lushan Earthquakes

“…The detection procedure follows that in Zhang and Wen (, ) and is described briefly here. The time length of the template waveform is 3 and 1 s before and 2 s after the arrival time of the Sg phase.…”

“…Microseismicity studies have been conducted in a wide range of fields for different purposes, such as the identification of fault plane (Kao & Shan, ; Mori & Hartzell, ); the detection of tectonic tremor, low frequency earthquakes and very low frequency earthquakes (Ito et al, ; Obara, ; Peng & Gomberg, ; Shelly, ; Shelly et al, ); the studies of seismicity before and after a large earthquake (Cesca et al, ; Kato et al, ; Nakamura et al, ; Tang et al, ; Yao et al, ); the monitoring of microseismic events induced by hydraulic fracturing in oil and gas industry (Eisner et al, ; Liang et al, ; Maxwell et al, ); and monitoring volcanic activity (Battaglia et al, ; Lengliné et al, ; Zhang & Wen, ). Two major aspects are essential in microseismicity study: identifying weak signals with a low signal‐to‐noise ratio (SNR) and constraining locations of small events.…”