Light Earthquake South of Dominica. Quake Reported Felt

At 8:17 PM Friday 17th January 2020, a Magnitude 4.4 (Md or Mt) earthquake occurred 39 kilometers southeast of Roseau, Dominica, and 55 kilometers north of Fort-de-France, Martinique.

This event occurred at an intermediate depth of 144 Kilometers. This information (above) is reviewed from the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean.

This earthquake was reported felt in St. Lucia, Martinique and Dominica. You can submit felt reports to the University of the West Indies Seismic Research Centre, the United States Geological Survey or the French Central Seismological Office.

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.

The United States Geological Survey registered this quake as a reviewed magnitude 4.8 (mb) at a similar depth of 140.1 kilometers, slightly further south and east from the SRC’s solution.

The French Seismological Central Office/Observatoire Volcanologique et Sismologique de Martinique also recorded this quake as a magnitude 4.3, at a depth of 139 kilometers.

An unofficial, non-authoritative organization in Dominica, Public Seismic Network Inc., Dominica, also published parameters for this quake, at a similar magnitude of 4.0 but notably shallower at 130 kilometers. This organization also located this quake at 15.078N, 61.185W, slightly more west and just south of the SRC’s solution.

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.

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.

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

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