TEMPORAL AND SPATIAL DISTRIBUTION OF SEISMIC SWARMS OF THE NORTHEASTERN PUERTO RICO - VIRGIN ISLANDS

The Puerto Rico Seismic Network (PRSN) has been monitoring seismic activity and locating earthquakes in the Puerto Rico-Virgin Islands (PRVI) region for more than 30 years. Peculiar heightened seismic activity has been recorded regularly northeast of the PRVI region. These frequent seismic activities are swarms and/or sequences that do not have a clear explanation as to their nature or occurrence. The seismic activity is typically characterized by numerous low-magnitude events spanning one day to several weeks. The combination of low magnitude events and the lack of seismic stations north or above the seismic activity result in an inability to properly determine nucleation depth and faulting mechanism. Attempts to dilucidate their nature has come from the deployment of Ocean Bottom seismographs (OBS) in 2005 and 2007. Here we present a history of these swarms and seismic sequences as a function of time and relate their different magnitudes events as a function of depth as located through PRSN's interactive iterative procedure. We also compare locations from swarms occurring in 2007 to those results obtained from the OBS re-location study.