This deployment is one of a series of studies planned to better assess the hazard from earthquakes, submarine slides, and tsunamis to Puerto Rico and the Virgin Islands. The data collected by the temporary array will be augmented by data collected by the permanent seismic stations of the Puerto Rico Seismic Network. The combined data 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 geographic 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 beneath the arrays.
Seismic velocity is a good proxy for the types of rocks at depth.
We also hope to learn about the attenuation of seismic energy from the earthquake at particular seismic stations. The internal components of each instrument are tested extensively before being loaded onto the ship. The study is co-funded by the CMGP, the Puerto Rico Department of Natural and Environmental Resources, the Sea Grant Office at the University of Puerto Rico in Mayaguez, and by the President's Office of the University of Puerto Rico. The marine component represents the largest number of OBSs deployed to date in a single emplacement, the first time that all newly designed USGS OBSs with external geophones were deployed, and the first time that USGS OBSs were deployed in a regional network to record earthquakes. Uri ten Brink about the goals of the cooperative experiment and the instruments.