Minor Earthquake Southwest of Dominica. No Shaking Reported.

At 11:10 AM Sunday 2nd February 2020, a Magnitude 3.9 (Md or Mt) earthquake occurred 35 kilometers South of Roseau, Dominica, and 56 kilometers northwest of Fort-de-France, Martinique.

This event occurred at an intermediate (and preliminary) depth of 153 Kilometers. This information (above) is preliminary from the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean. This event has not been reviewed by an analyst. It was automatically located by a seismological computational system and it may vary when new additional data are processed.

This earthquake was not reported felt. You can submit felt reports to the University of the West Indies Seismic Research Centre.

There is no tsunami threat.

There are four conditions necessary for an earthquake to cause a tsunami:

  1. The earthquake must occur beneath the ocean or cause material to slide in the ocean.
  2. The earthquake must be strong, at least magnitude 6.5.
  3. The earthquake must rupture the Earth’s surface and it must occur at shallow depth – less than 70 KM below the surface of the Earth.
  4. The earthquake must cause vertical movement of the seafloor (up to several meters).

None of these conditions occurred.

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 the uncertainty of that data. This is generally accepted within the scientific community.

Based on the location and depth of this earthquake, it is tectonic in origin and occurred within the Caribbean Plate, above the subducting South American plate to the east.

This quake occurred within a highly seismic area, with quakes occurring up to magnitude 7.3 since 1960, and a majority of quakes occurring below 100-kilometer depth, though weaker and shallower quakes have been recorded.

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

https://ttweathercenter.com/eq-faq/earthquake-prediction-forecasting

Generally, across the Eastern Caribbean, a seismically active area, earthquakes of this magnitude, up to M8.0 and greater, are possible 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.

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.

In Dominica, there is a period of volcanic unrest ongoing, which is effectively a period of elevated seismic activity. In our ongoing situation, unrest is particularly affecting the southern half of Dominica which began in December 2018.

Since the beginning of the unrest period, there have been several earthquakes recorded daily, with periodic intense bursts of quakes, some of which are felt by the population.

Although this quake was tectonic in origin, as the South American plate subducts under the Caribbean Plate, and not directly related to any one of the many volcanoes, this process of subduction is what feeds these volcanoes with magma.

The University of the West Indies Seismic Research Centre continues to monitor the unfolding situation.

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