On the possibility of the 2011 Tohoku-oki earthquake reactivating Shinmoe-dake volcano, southwest Japan: insights from strain data measured in vaults

• Main Authors: K. Yamazaki, M. Teraishi, S. Komatsu, Y. Sonoda, Y. Kano
• Format: Article
• Language: English
• Published: Copernicus Publications 2011-09-01
• Series: Natural Hazards and Earth System Sciences
• Online Access: http://www.nat-hazards-earth-syst-sci.net/11/2655/2011/nhess-11-2655-2011.pdf

The Shinmoe-dake volcano in southwest Japan, which produced its first major eruption in 52 yr on 26 January 2011 but had been quiescent since 1 March, re-erupted on 13 March. It was only two days after the occurrence of the <i>M</i> = 9.0 Tohoku-oki earthquake in eastern Japan. The coincidence of the two events raises the question of whether the earthquake triggered the volcanic activity. As a provisional but rapid assessment of this question, we examined high-resolution strain data at a site located 18 km from Shinmoe-dake. In terms of the Tohoku-oki earthquake, three points can be drawn from the strain data: (1) static strain changes were less than 0.05 × 10<sup>−6</sup>, which is too small to trigger an eruption; (2) the amplitudes of dynamic strain changes are on the order of 10<sup>−6</sup>, which may trigger seismicity or volcanic eruption; and (3) strain rates were not accelerated, which indicates no significant change in magma pressure. Comparing these results with reports of other eruptions coincident with seismic events, and considering a scenario in which a seismic event triggered an eruption, we tentatively conclude that the eruption on 13 March was not a triggered event. However, this conclusion may be revised after analyzing seismic data.