8:23PM: Minor M3.9 Earthquake Southeast of Grenada

At 8:23PM Tuesday 2nd April 2019, a Magnitude 3.9 (Md or mt) earthquake occurred 11.89 Kilometers Southeast of St. George’s, Grenada and 138.6 KM NW of Scarborough, Trinidad and Tobago. This event occurred at a moderate depth of 97.0 Kilometers. This information was reviewed by an analyst from the University of the West Indies Seismic Research Centre.

Note that across the globe, different seismic monitoring agencies use different methods, or several methods, for processing earthquake parameters. Each method has its limitations and will likely produce different results within the ranges of uncertainty of that data. This is generally accepted within the scientific community.

Related: Earthquake Magnitude & Intensity

This event was not reported felt. However, you can submit felt reports to the University of the West Indies Seismic Research Centre.

Based on the location and depth of this earthquake, it likely occurred within the subducting slab of the South American plate. Across the Eastern Caribbean, the South American plate rapidly descends into the Earth’s mantle as the detached oceanic lithosphere exists at depths between 50 to 300 kilometers. (Russo et al. 1993). This subduction is what causes volcanism across the Eastern Caribbean islands.

This earthquake is not related to the Kick’em Jenny submarine volcano north-northeast of Grenada. Kick’em Jenny’s alert level remains at yellow. The largest magnitude events in this specific area, near this depth, have topped out at Magnitude 5.5, occurring in 2017 and 1985.

Earthquakes *cannot* be predicted – meaning the precise time, date, magnitude, depth etc. cannot be known ahead of time based on current research and technology.

Related: Earthquake Prediction and Forecasting

Generally, in the Eastern Caribbean, a seismically active area, earthquakes of this magnitude, up to M8.0 and greater, are possible in area, and this statement has been repeated by seismologists at the U.W.I. Seismic Research Centre for decades.

Each year, over 2,200 seismic events are recorded in the Eastern Caribbean. On average, the Eastern Caribbean has seen a pattern of major (M7.0-M7.9) quakes every 20 to 30 years. That pattern has stayed true. The last major (M7.0-7.9) quake occurred north of Martinique in 2007. 

Historical patterns indicate great earthquakes (M8.0+) on the Richter Scale have occurred every century or so in the region. The probability of another event at that level is high since the last >M8.0 earthquake occurred in 1843.

Related: Earthquake Safety

Now is the time to create or go over your earthquake preparedness plan and know what to do during, before and after an earthquake. See here for more details.

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