Last night at midnight (12:01am) was a 6.4 magnitude earthquake 77 kilometers from Quebradillas, Puerto Rico. This was followed by many other aftershocks ranging from 2.9 to 3.7 on the Richter scale (see http://es.earthquaketrack.com/r/puerto-rico/recent). Luckily, any fears of a possible tsunami were dismissed. Here are excerpts from an article from El Nuevo Día (in Spanish):
Some 70 aftershocks have been reported since the midnight 6.4 earthquake occurred in the fault at 19 degrees north, 77 kilometers away from Quebradillas, said geologist Francis Pérez of the Puerto Rico Seismic Network. “That number may continue to rise,” he said, specifying that there was no tsunami warning.
Moreover, Pérez said about 440 reports of tremors were reported by the Seismic Network after the initial 6.4 earthquake. They suggest that the quake was felt throughout the island. There were no records in the municipalities of Vieques and Culebra, said the geologist. This major earthquake occurred at 12:01am. “It was at the fault zone of 19 degrees north of Puerto Rico. That is below the fault known as the Puerto Rico Trench. It was at a depth of 36 kilometers. Being an event that is not too deep, it was expected that it was felt strongly. And being at such a large scale, we have had reports from all over Puerto Rico,” he explained.
Reports suggest that the intensity of the earthquake was V on the Mercalli scale. This record came from the town of Arecibo. This represents that it was “felt by nearly everyone, many were awakened by it. Some dishes, windows, etc., are broken, some houses have cracked masonry. Unstable objects overturned. Pendulum clocks stop. Swing doors open and close. Trees and bushes shake visibly. [. . .] That is the maximum intensity we have felt,” he said.
This fault at 19 degrees north of the island, where the earthquakes have been reported in the last few hours, “is quite active. Usually, when such a big earthquake happens, at faults that are active during the year, there is a period of settling. Hence we see many aftershocks. Many more will still add up to the ones that have been felt so far.”
This earthquake is the most intense one felt on the island since 1918, when an earthquake of 7.5 magnitude was reported in the Mona Passage fault, which left many collapsed buildings in the area of Mayagüez.