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Puerto Rico Seismic Activity (December 2019 to May 2020)

posted Jan 15, 2020, 12:16 PM by Abel Mendez   [ updated May 2, 2020, 5:04 PM ]
Last Update: Sat May  2 20:00:47 2020

These plots show a general summary of the seismic activity in the southwest of Puerto Rico from December 15, 2019 until today. Data includes all magnitudes earthquakes (mag > 1.0)*, including automatic detections, from the USGS Earth Quake Catalog

Figure #1. Number of daily earthquakes as a function of time.


Figure #2. Magnitude of earthquakes (red line) and daily mean magnitude (black line) as a function of time.


Figure #3. Magnitude of earthquakes as a function of time of day.


Figure #4. Daily mean (black) and total energy (red) of earthquakes converted to the magnitude scale as a function of time.


Figure #5. Lomb-Scargle Periodogram of the magnitude of earthquakes. This plot shows the periodic signals observed, not predicted, in all the data shown in previous figures. Those signals about the blue dotted line are more significant.

Figure #6. The expected decay rate of the number of earthquakes since the M6.4 Jan 07 event.



Figure #7. Integrated seismic energy deposited by all the earthquakes mag ≥ 4 near Puerto Rico in the last 120 years. Actual earthquakes used to generate this plot are shown in grey.


Table #1. The "equivalent magnitude" of major earthquakes (mag ≥ 5.0) for Guayanilla, Ponce, Utuado, Mayagüez, Arecibo, Vega Baja, San Juan, and Fajardo. This "equivalent magnitude" gives a general sense of the perceived magnitude of a particular earthquake assuming it happened near your location instead. For example, the 6.4 earthquake of January 7 released about the same surface energy on San Juan as a 4.8 earthquake 10 km below San Juan.


A decrease in the numbers (red boxes in figure 1) and an increase in the mean magnitude for mag > 1.0 (black line of figure 2) of earthquakes in the last 3 to 5 days is artificial. The data lacks low magnitude quakes in the last days since they take longer to be processed. Data and live interactive maps are available from the USGS.

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