Very strong earthquake out of the coast of Puerto Rico – also felt in the Dominican Republic

Last update: January 13, 2014 at 11:46 am by By Ashish Khanal

Update 11:43 UTC : Many people living in the coastal areas auto-evacuated their houses in search for higher ground. An idea earthquake-report.com welcomes as waiting for official alerts always has a small risk.

Update 09:17 UTC : There were also power cuts who where restored shortly after the quake. Due these power cuts the Puerto Rico Seismic Network ceased operations a few seconds after the earthquake occurred !
Many people left their houses in search for higher grounds

Understanding the January 13 Puerto Rico earthquake
The January 13, 2014 M 6.4 earthquake north of Puerto Rico occurred as a result of oblique-thrust faulting. Preliminary faulting mechanisms for the event indicate it ruptured either a structure dipping shallowly to the south and striking approximately east-west, or a near-vertical structure striking northwest-southeast. At the location of this earthquake, the North America plate moves west-southwest with respect to the Caribbean plate at a velocity of approximately 20 mm/yr, and subducts beneath the Caribbean plate at the Puerto Rico Trench.  The location, depth and mechanism of the earthquake are consistent with the event occurring on this subduction zone interface.
While the Puerto Rico Trench is known to be a significant seismic hazard, and is capable of hosting M8+ earthquakes, moderate-to-large events on the subduction zone are rare.
Over the past century, three such events have occurred nearby to the January 13, 2014 earthquake – a M 6.6 event in 1915, just to the east of the 2014 event; a M 7.0 earthquake 70 km to the west in 1917; and a M 7.6 earthquake in 1943 just northwest of the 2014 earthquake. Two earthquakes occurred in the Mona Passage approximately 100 km to the southwest of the 2014 earthquake in 1916 (M 7.0) and 1918 (M 7.3), while the 1946 M 7.9-8.0 Hispaniola earthquake struck 230 km to the west, also on the North America slab interface. The July 1943 North Mona Passage earthquake did not cause significant damage in Puerto Rico, though it did spawn a small tsunami, and was the first in a series of large events in the broader northern Caribbean region between central Hispaniola and Puerto Rico over the following decade, including the larger 1946 earthquake. The 1946 event is known to have caused significant damage in both Hispaniola and Puerto Rico, including destruction from a subsequent tsunami.

Update 06:53 UTC : Some minor damage is reported from Puerto Rico. Nothing serious, but people are mentioning cracks in walls.

Twitter damage image from Puerto Rico

Update 05:06 UTC : USGS has lowered the shaking intensity after recalculations. We do confirm that the new numbers are much more reflecting what our readers are telling us.

Update 05:04 UTC : NO reports of serious damage has reached us so far. Broken falling objects are reported bu that happens often in case of moderate shaking.

Update 04:59 UTC : It would be wise NOT to swim in the ocean the next hours as strong currents could have been generated by the earthquake. Almost nobody will do so as it is night at the moment in Puerto Rico

Update 04:58 UTC : The earthquake occurred in the deep Ocean Trench. This was not the strongest earthquake in the area so far. As can be seen on our bottom map, a M7.3 Magnitude earthquake happened right below Puerto Rico in 1918!

Official Tsunami statement of the PTWC :
A DESTRUCTIVE WIDESPREAD TSUNAMI THREAT DOES NOT EXIST BASED ON  HISTORICAL EARTHQUAKE AND TSUNAMI DATA.
HOWEVER – THERE IS THE SMALL POSSIBILITY OF A LOCAL TSUNAMI THAT  COULD AFFECT COASTS LOCATED USUALLY NO MORE THAN A HUNDRED  KILOMETERS FROM THE EARTHQUAKE EPICENTER. AUTHORITIES IN THE  REGION NEAR THE EPICENTER SHOULD BE MADE AWARE OF THIS  POSSIBILITY.

Update 04:39 UTC : The pictures below are showing the theoretical shaking intensity. In general we can say that this was a lucky escape for Puerto Rico. 30 km more to the south and serious damage could have been expected at the Northern Puerto Rico coast.

Update : The shaking intensities as reported by our readers in Puerto Rico are leveraging a light to moderate shaking – weak shaking in the Dominican Republic

NO risk for a tsunami

Theoretical calculations from USGS are expecting a strong shaking at the northern coast of Puerto Rico

56km (35mi) N of Hatillo, Puerto Rico
58km (36mi) NNE of Isabela, Puerto Rico
59km (37mi) NNW of Arecibo, Puerto Rico
67km (42mi) NNW of Barceloneta, Puerto Rico
96km (60mi) NW of San Juan, Puerto Rico

Most important Earthquake Data:

Magnitude : 6.5

from:    http://earthquake-report.com/2014/01/13/strong-earthquake-hatillo-puerto-rico-on-january-13-2014/