9:12 AM: Light M4.1 Earthquake West of Trinidad.

At 9:12 AM on Wednesday 31st July 2019, a preliminary Magnitude 4.1 (Md or Mt) earthquake occurred 9.67 KM NW of Irapa, Venezuela and 123.68 KM W of Port of Spain, Trinidad and Tobago.

This event occurred at a shallow depth of 10 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. Quake parameters such as location, depth, and magnitude may change upon review from a seismologist at the SRC.

This event was not reported felt across Trinidad, and we’ve seen no felt reports for this event across northeastern Venezuela. You can submit your felt reports to the U.W.I. Seismic Research Center.

FUNVISIS' preliminary solution for the light quake west of Trinidad at 9:12 AM
FUNVISIS’ preliminary solution for the light quake west of Trinidad at 9:12 AM

The Venezuelan Foundation for Seismological Research (FUNVISIS) also recorded this earthquake, at a preliminary Magnitude 4.2 (MW) further south and west of UWI SRC’s preliminary solution. According to FUNVISIS, this quake occurred 15.28 KM SE of Irapa, Venezuela and 107.56 KM WSW of Port of Spain, Trinidad and Tobago at a depth of 25.6 kilometers.

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.

Based on the location and depth of this earthquake, it is tectonic in origin and occurred within seismic zone 1, the Paria Peninsula.

Earthquakes in Zone 1 occur in 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, where this quake occurred according to UWI SRC’s parameters, 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.

Based on the preliminary parameters from FUNVISIS, this quake could have also occurred within the northwestern Gulf of Paria. The Gulf of Paria is a very faulted, seismically complex area surrounding Trinidad. In this zone, Zone 3, 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.

Within 20 kilometers of the epicenter of the main earthquake, since 1960, there have been over 670 recorded events, at all depths. When looking at the depths where this quake occurred, due to the El Pilar Fault zone, since 1960, there have been over 200 quakes recorded above 50 kilometers depth, with the strongest recorded as a magnitude 5.1 on July 9th, 1997.

The most recent quake in the area, above M4.0, was on May 31st, 2019, at a magnitude 4.5. Interesting to note that just southeast of today’s M4.1/M4.2 event, the August 21st, 2019 M6.9 earthquake occurred. However, this event was due to the subduction of the South American Plate under the Caribbean plate at an intermediate to deep depth, whereas today’s event was due to strike-slip motion at shallower depths.

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.

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