I found an article regarding this topic on the USGS website.
The area northeast of Puerto Rico is characterized by frequent swarms of seismic tremors lasting a week or two at a time. One such swarm in 2001 included three earthquakes with moment magnitudes of 5.5 to 6. Although the cause of these recurring swarms is unknown, a study of earthquake hypocenters (points where earthquake ruptures begin), using data from OBSes deployed by the USGS in 2005, suggests that the tremors originate along the subduction zone between the North American and Caribbean tectonic plates.
source
I was unaware this region was so seismically active.
If confirmed by analysis of the recently acquired OBS data, the locations of the tremors at the plate interface may have profound implications about the capability of the Puerto Rico Trench to generate large earthquakes. Additionally, the tectonic setting of the Puerto Rico Trench is sometimes compared to that of the Sumatra subduction zone, the site of the earthquake that triggered the devastating Indian Ocean tsunami of December 2004. This similarity has caused great interest in the assessment of potential tsunami hazard to the United States east coast and the northeastern Caribbean from a large subduction-zone earthquake along the Puerto Rico Trench.
All five OBSes recorded data during the entire 6-month deployment. As it happened, the region was unusually active, with three swarms and at least 518 earthquakes. The OBS data are currently being merged with seismic data recorded on land in Puerto Rico and the Virgin Islands...
I'm no scientist, but I did have a vivid dream four nights ago (while I was staying at a Holiday Inn Express
) in which I saw massive waves
crashing on the beach of what I was told was Aruba. That is what drew my attention to this thread.
