enough already ! 5.9 today :(
Posted by cypresstx on 1/11/2020, 5:56 pm
https://www.courthousenews.com/magnitude-5-9-shock-again-rocks-quake-stunned-puerto-rico/

https://earthquake.usgs.gov/earthquakes/eventpage/us70006ydb/executive

Tectonic Summary

The January 11, 2020, M 5.9 earthquake southwest of Puerto Rico is the latest in a series of strong earthquakes in the same region over the past 2 weeks. This sequence began with a M 4.7 earthquake late on December 28 and a M 5.0 event a few hours later. The largest event in this sequence to date is a M 6.4 earthquake on January 7, which was preceded a day earlier by a M 5.8 event. Since the late December 2019, close to 1,000 M 2+ earthquakes have occurred in this region (400 since the M 6.4 on January 7, the current mainshock), 50 of which were M 4+ (39 since current mainshock), and eight of which were M 5+ (5 since mainshock). The proximity of these events to Puerto Rico, and their shallow depth, mean that many of the M3 and above earthquakes have likely been felt on land.

The earthquakes in this series of events are occurring as the result of intraplate faulting in the offshore deformation zone bound by the Punta Montalva Fault on land and the Guayanilla Canyon offshore. These earthquakes have shown some variation in faulting, mixed between strike slip and normal faulting. The latest January 11, M 5.9 event occurred as the result of normal faulting, with slip on either a shallow plane dipping towards the northwest, or on a steep plane dipping towards the south. This mechanism is consistent with the January 7, M 6.4 mainshock, which demonstrated oblique-normal faulting, and many of the aftershocks since that time. Early events in this sequence, and some of the aftershocks since the M 6.4 event, occurred as the result of strike slip faulting on either a left-lateral plane oriented WNW-ESE, or on a right lateral plane oriented NNE-SSW.

Tectonics in Puerto Rico are dominated by the convergence between the North America and Caribbean plates, with the island being squeezed between the two. To the north of Puerto Rico, North America subducts beneath the Caribbean plate along the Puerto Rico trench. To the south of the island, and south of todays earthquake, Caribbean plate lithosphere subducts beneath Puerto Rico at the Muertos Trough. While large earthquakes in this region are rare, infrequent naturally occurring large earthquakes are expected given the active tectonic setting. The occurrence of this earthquake is also consistent with latest USGS aftershock forecasts after the M 6.4 event, which prior to this event indicated a 10% probability of a magnitude 6 or above earthquake within a week.
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Puerto Rico earthquakes - cypresstx, 1/7/2020, 4:50 am
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