A week after the first small steam-driven explosive eruption of Soufriere Hills volcano in Monsterrat on July 18, 1995, a team of scientists from the U.S. Geological Survey was dispatched to assist in the monitoring effort led by the Univeristy of the West Indies. The USGS team helpted to install seismic stations, seismographs (above), tiltmeters, and a data acquisition and analysis system for locating earthquakes and tracking seismic energy release. Magma reached the surface about 9 weeks later and built a lava dome that continued to grow for the next few years.

Earthquake activity beneath a volcano is the most common precursor to an eruption. Unfortunately, the pattern of earthquakes (type, location, frequency, magnitude) recorded by seismic networks before many recent eruptions has varied significantly from one volcano to another and even from one eruption to another at the same volcano. Scientists must draw upon experience gained at many active volcanoes in the world and use other monitoring methods to intepret seismic activity and provide timely warnings of an eruption.