25 Volcano seismology and monitoring for eruptions

Abstract

Seismology is considered one of the most useful tools for eruption forecasting and monitoring. Volcanoes are the sources of a great variety of seismic signals that behave differently than those from events on earthquake faults. Every recorded volcanic eruption is preceded by an increase in earthquake activity beneath or near the volcano and accompanied and followed by varying levels of seismicity. This chapter reviews some of the developments in volcano seismology that have led to an improved understanding of volcanoes and the volcanic processes that cause earthquakes and other seismicity. It also describes patterns and relationships in volcano seismology that form the physical basis of contemporary monitoring and forecasting. The key developments in volcano seismology are often driven by different types of seismic events that volcanoes produce. Some of the significant characteristics explored by volcano seismology include: (1) tomography and b value anomalies, which have identified large magmatic or near-magmatic structures, while low frequency events and volcanic tremor are associated with small scale movement of magma or water, (2) normal earthquake activity at volcanoes varies widely with a number of systematic trends, and (3) understanding and modeling of physical processes and study of many case histories helps to know about the next happening.