The network was installed to record local and regional earthquakes as part of a series of studies planned to better assess the hazard to Puerto Rico and the Virgin Islands from earthquakes, submarine slides, and tsunamis. The data collected by the temporary array were augmented by data collected by the permanent seismic stations of the Puerto Rico Seismic Network. The combined data sets will be used to locate earthquakes more accurately than is presently possible, because the accuracy of an earthquake location depends on the distance from the earthquake to the seismometers and on the geographical distribution of the seismometers. Many of the marine and land seismometers were placed at intervals of 15-25 km along two perpendicular arrays. The data from these arrays will be used to construct seismic-velocity maps of the Earth's crust under the arrays.
Seismic velocity is a good proxy for the types of rocks at depth.
USGS scientists also hope to learn about the attenuation of seismic energy from the earthquake at particular seismic stations. This study is being carried out jointly by the USGS Coastal and Marine Program in Woods Hole and by the Puerto Rico Seismic Network at the University of Puerto Rico. The three temporarily installed land seismometers were picked up by Russell Sell and Erich Roth at the end of the cruise. The marine component represents the largest number of OBSs to date in a single deployment, the first time that all newly designed USGS OBSs with external geophones were used, and the first time that USGS OBSs were deployed in a regional network to record earthquakes. The modified OBSs represent the culmination of several years of hard work by Greg Miller and Ray Davis to upgrade the instruments in order to improve their new mission of recording earthquakes better.