This event occurred at a depth of 72 Kilometers. This information has been reviewed by seismologists at France’s Réseau National de surveillance sismique.
Note that this quake likely fell below the magnitude 3.8 threshold for public reporting from the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean.
This event was not reported felt. 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:
- The earthquake must occur beneath the ocean or cause material to slide in the ocean.
- The earthquake must be strong, at least magnitude 6.5.
- 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.
- The earthquake must cause vertical movement of the seafloor (up to several meters).
These conditions were not met.
Based on the location and depth of this earthquake, it is tectonic in origin. In this area, the South American plate is beginning to 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 40-45 kilometers depth. Based on the depth of the event provided by RéNaSS, this quake occurred within the subducting South American plate.
Within 20 kilometers of the epicenter of this earthquake, since the 1970s, there have been 17 recorded events with varying depths – from 0 KM to 200 KM, with the majority of quakes occurring below a 55-kilometer depth.
Based on records going back to the 1970s the largest quake that occurred in this area was recorded as magnitude 4.4 (Md) quakes, occurring on February 12th, 2020, exactly one year from the 2021 quake. All other quakes have registered below magnitude 4.0 in the area.
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.