11:26 PM – Moderate Earthquake Felt Across T&T, Southern Windwards

At 11:26 PM Monday 6th April 2020, a moderate (reviewed) Magnitude 5.3 (Md or Mt) earthquake struck 53.15 KM NW of Scarborough, Trinidad and Tobago, 97.08 KM SW of St. George’s, Grenada and 112.82 KM NW of Port of Spain, Trinidad and Tobago.

UWI SRC's reviewed solution for the M5.3 earthquake at 11:26 PM Monday 6th April 2020
UWI SRC’s reviewed solution for the M5.3 earthquake at 11:26 PM Monday 6th April 2020

This event occurred at a depth of 22 Kilometers. This information is reviewed by the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean.

This event has been reported felt across parts of Trinidad, Tobago, Grenada, Northeastern Venezuela, St. Lucia and St. Vincent and the Grenadines as a small jolt, lasting no longer than 5-15 seconds. You can submit felt reports to the University of the West Indies Seismic Research Centre, the United States Geological Service and the European-Mediterranean Seismological Center.

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).

These conditions were not met.

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.

USGS’ reviewed solution for tonight’s earthquake.
USGS’ reviewed solution for tonight’s earthquake.

The United States Geological Survey (USGS) also recorded this quake, at a reviewed Magnitude 5.2 (mww) further west of the UWI SRC’s preliminary solution. According to the USGS, this quake occurred at a slightly deeper depth of 31 kilometers.

EMSC’s reviewed solution for tonight’s earthquake.
EMSC’s reviewed solution for tonight’s earthquake.

The European-Mediterranean Seismological Center (EMSC) also recorded this quake, at a preliminary Magnitude 5.2 (mb) in a similar location to UWI SRC and the USGS. According to the EMSC, this quake occurred at a depth of 30.0 kilometers.

Based on the location and depth of this earthquake, it is tectonic in origin. In this area, 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).

In this location, the subducting slab is at approximately 50 kilometers depth, but based on the depths provided by UWI SRC, USGS and EMSC, this quake occurred within the overriding Caribbean Plate. Occurring near the Wadati–Benioff zone, where the subducting slab (South American Plate) interacts with the overriding slab (Caribbean Plate).

Within 20 kilometers of the epicenter of this earthquake, since 1960, there have been 76 recorded events with varying depths – from 0 KM to 138 KM.

Based on records going back to the 1960s, if the location of this quake doesn’t drastically change, this will be one of the strongest quakes within the 20-kilometer radius in recent, recorded history. The largest quake that occurred in this area was recorded as magnitude 5.6 (Md) quakes, occurring on April 2nd, 1997 at 2:14 AM. All other quakes have registered below magnitude 5.0.

If you expand that radius to 45 kilometers, we also encounter a magnitude 6.1 that occurred on April 22nd, 1997 closer to Tobago at a 11.162N and 61.091W with another moderate quake, at Magnitude 5.7 on November 5th, 2019 further north at 11.83N, 61.06W.

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.

Facebook Comments