According, to reports issued by the Puerto Rico Seismic Network, an earthquake measuring a magnitude of 4.6 on the Richter scale was felt throughout Puerto Rico and the British Virgin Islands on yesterday (Tuesday, July 21, 2009) afternoon at approximately 3:00pm. The report indicated that the epicenter was located near 19.26 north latitude and 64.77 west longitude, or 75 km north east of Anegada, at a depth of 21 kilometers.
The Virgin Islands is in a seismically active zone, which makes the region vulnerable to earthquakes. Puerto Rico has also had at least four strong earthquakes since the beginning of its colonization, in 1670, 1787, 1867, and 1918. These were all thought to have had an approximate magnitude between 7.5 and 8.00 (in 1787) on the Richter scale. Two of these produced tsunamis and all produced major devastation. One of these, like yesterday’s earthquake, had its epicenter in the Anegada Passage.
People who felt the earthquake yesterday can assist the Department of Disaster Management and the Puerto Rico Seismic Network in determining its intensity by logging on to http://pasadena.wr.usgs.gov/shake/ous/html/BritishVirginIslandsForm.shtml and completing an electronic form.
Photo of Anegada from http://www.nwmangum.com/Caribbean.html