On the shallow volcanic response to remote seismicity

It is a primary goal within the volcano monitoring community to develop improved observational data assessments and early warning for hazardous eruptions. It has become increasingly apparent over the past three decades that volcanic activity may be modulated by large earthquakes (e.g., Hill, et al., 1993), even at great distances. In many cases, the influence has been minor, including the perturbation of hydrothermal systems and expressed by changes in temperature, gas flux, or seismicity (Cox et al., 2015). For a small number (~4%) of large earthquakes (> Mw 7), a moderate or large eruption (>VEI 2; Volcanic Explosivity Index) may occur (e.g., Linde and Sacks, 1998; Manga and Brodsky, 2006). It is clear that the volcano monitoring community needs to focus on unrest processes related to large remote earthquakes, and how these relationships can be exploited to improve safety. A new contribution by Namiki et al. (p. 67 in this issue of Geology), uses analogue and computer simulations to understand the propagation of cracks under the dynamic stress from passing seismic waves. The work utilized a range of edifice aspect ratios, fluid characteristics, and external source excitations to develop an understanding of crack propagation and fluid flow as an analogue to natural volcanic systems. The experimental results demonstrated the importance of external seismic waves as a driver of volcanic edifice resonance and subsequent propagation of variably buoyant cracks. It is useful to outline the relevant mechanisms within shallow volcanic systems, and some of the ways that Namiki et al.’s work could be exploited to promote new research and to enhance volcano monitoring outcomes.