[Updated] 10:35 PM – Earthquake Southwest of Trinidad. Shaking Reported.

Update: The UWI SRC has indicated that due to a technical error, an incorrect auto-solution was provided for the earthquake on Tuesday night. The data has been reviewed by a seismologist.

At 10:35 PM Tuesday 5th January 2021, a reviewed light Magnitude 4.1 (Md or Mt) earthquake occurred 64.2 km SSE of Güiria, Venezuela, 84.8 km WSW of San Fernando, Trinidad and Tobago, and 101.4 km SW of Port of Spain, Trinidad and Tobago. This event occurred at a depth of 49.51 kilometers.

Reviewed information from the University of the West Indies Seismic Research Centre concerning the M4.1 Earthquake west of Trinidad and Tobago.
Reviewed information from the University of the West Indies Seismic Research Centre concerning the M4.1 Earthquake west of Trinidad and Tobago.

Original Story

At 10:36 PM Tuesday 5th January 2021, a preliminary light Magnitude 4.2 (Md or Mt) earthquake occurred 23 km SSW of St. George’s, Grenada, 135 km NNW of Port of Spain, Trinidad and Tobago and 138 km NW of Scarborough, Trinidad and Tobago.

This event occurred at a depth of 10 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.

Other seismic research institutions place this quake in the Gulf of Paria. Given that shaking was reported across southwestern and northwestern Trinidad, this is the likely location. This post will be updated when additional information is provided by UWI SRC.

Preliminary information from the University of the West Indies Seismic Research Centre concerning the M4.2 Earthquake north of Trinidad and Tobago.
Preliminary information from the University of the West Indies Seismic Research Centre concerning the M4.2 Earthquake north of Trinidad and Tobago.

This event has been reported felt across northwestern (Diego Martin and Cascade) and southwestern (Siparia, Point Fortin) areas of Trinidad. Notably, there have been no felt reports in Grenada, given the preliminary location from the UWI SRC. 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 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.

Reviewed information from the United States Geological Survey concerning the M4.4 Earthquake west of Trinidad and Tobago.
Reviewed information from the United States Geological Survey concerning the M4.4 Earthquake west of Trinidad and Tobago.

The United States Geological Survey places this quake in the Gulf of Paria, west of T&T at a depth of 10 kilometers but a similar magnitude of 4.5 (mb).

Preliminary information from FUNVISIS concerning the M4.4 (UWI SRC M4.2) Earthquake west of Trinidad.
Preliminary information from FUNVISIS concerning the M4.4 (UWI SRC M4.2) Earthquake west of Trinidad.

The Venezuelan Foundation for Seismological Research (FUNVISIS) also recorded this quake at a magnitude 4.4 (Mw) at a shallow depth of 15.8 kilometres,, well south and west from the UWI SRC solution.

Based on felt reports and other seismic solutions (outside of the UWI SRC), This quake occurred in seismic zone 1, in the Paria Peninsula.

This quake occurred along one of the many strike-slip faults in the Gulf of Paria, in Seismic Zone Three.

The Gulf of Paria is yet another very faulted, seismically complex area surrounding Trinidad. At this zone, the extension of the Los Bajos fault from southwestern Trinidad, and the Warm Springs Fault from Central Trinidad meets the El Pilar fault. This complex network of faults also includes small, conjugate, or perpendicular faults.

High levels of seismic activity occur in this zone, with both shallow and moderate depth earthquakes, generally remaining less than 50 kilometers depth. The UWI SRC has stated during a Q&A of the earthquake swarm between January and February 2018, this location is capable of generating a magnitude 6.5 or greater earthquake.

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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