2:48 PM – Minor M3.9 Earthquake NW of Trinidad

At 2:48 PM Wednesday 23rd December 2020, a preliminary minor Magnitude 3.9 (Md or Mt) earthquake occurred 33.2 km NE of Macuro, Venezuela, 39.3 km NW of Port of Spain, Trinidad and Tobago and 76.4 km NW of San Fernando, Trinidad and Tobago.

This event occurred at a depth of 42.72 Kilometers. This information (above) is preliminary by the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean. This information may change when additional data is processed by a seismologist.

Preliminary information from the University of the West Indies Seismic Research Centre concerning the M3.9 Earthquake northwest of Trinidad and Tobago.
Preliminary information from the University of the West Indies Seismic Research Centre concerning the M3.9 Earthquake northwest of Trinidad and Tobago.

Very minor cracks have been reported across parts of Northern Trinidad, with small cracks appearing on some homes in Maracas, St. Joseph, and Five Rivers, Arouca.

Minor plaster damage in Five Rivers, Arouca following Wednesday afternoon's earthquake near Trinidad.
Minor plaster damage in Five Rivers, Arouca following Wednesday afternoon’s earthquake near Trinidad.

This event has been reported felt across the northern half of Trinidad. Most reported a rumble proceeded by a short jolt. 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.

Seismic signal recorded at Grenville, Grenada for the light magnitude earthquake northwest of Trinidad Wednesday afternoon.

Note that across the globe, different seismic monitoring agencies use different methods, or several methods, for processing quake 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.

This quake occurred in seismic zone 1, in the Paria Peninsula.

Seismic zone one is a complex, and without a doubt, the most seismically active area near Trinidad. Within zone one, the South American plate is beginning to rapidly descend into the Earth’s mantle as the detached oceanic lithosphere exists at depths between 50 to 300 kilometers. (Russo et al. 1993). This zone is one of the most active seismogenic sources in the Eastern Caribbean and has the potential to generate earthquakes up to Magnitude 8.0.

At shallower levels the North Coast Fault Zone, as well as the El Pilar Fault, part of the Boconó-San Sebastian-El Pilar Fault system, run across Zone 1. These fault systems compensate for the stress built up as the Caribbean plate slides past the South American plate. Hence, most of these earthquakes from these fault systems are shallow to moderate between 0 to 70 kilometers.

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 quakes (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.

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