The United States Geological Survey recorded
a Magnitude 4.8 Earthquake at a depth of 42 km roughly 50 km north of Puerto RIco, slightly before 4.15 pm local time (slightly before 8.15 pm GMT) on Friday 18 August 2017.
This was a moderate quake, and at some
depth as well as some way offshore, and there are no reports of any
casualties or serious damage, though the quake was felt across Peurto Rico.
The approximate location of the 18 August 2017 Puerto Rico Earthquake. USGS.
Puerto Rico is located at the northeastern fringe of the Caribbean
Tectonic Plate. The Atlantic Plate (strictly speaking, an extension of
the South American Plate which runs to the northeast of the Caribbean)
is being subducted beneath this. The subduction of the Atlantic Plate beneath the
Caribbean Plate is not a smooth process, with the two plates constantly
sticking together then breaking apart as the tectonic pressure builds
up, causing Earthquakes in the process, though since the boundary
between the two plates is some way to the north and east of the islands,
Earthquakes in this area tend to be both deep and offshore,
which lessens their destructive potential.
The subduction of the Atlantic Plate beneath the Caribbean Plate fuels the volcanoes of the Lesser Antilles Volcanic Arc. George Pararas-Carayannis.
Witness
accounts of quakes can help geologists to understand these events and
the rock structures that cause them. If you felt this quake (or if you
were in the area but did not, which is also useful information) you can
report it to the USGS here.
See also...
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