An unusually high-magnitude earthquake has struck a remote area of Guyana at 3:05 PM, Sunday 31st January 2021. Preliminary data registers this quake between a moderate magnitude 5.7 to a strong magnitude 6.1, placing today’s quake as the strongest seismic event in modern records to strike Guyana.
There has been no reports of injuries or damage at this time.
Based on reviewed information from the United States Geological Survey, this magnitude 5.7 event struck at 9.7 kilometers deep, at a location of 2.644°N, 59.629°W. This places the event at 84.4 KM SE of Lethem, Guyana, 117.8 KM E of Boa Vista, Brazil, 402.1 KM SSW of Linden, Guyana. Based on its very shallow depth, strong to very strong shaking is possible.
As the event occurred in a remote area of Guyana and in South America, population centers were well displaced from the epicenter. Still, moderate to strong shaking was reported across parts of Guyana, northern-most areas of Brazil, and southeastern-most areas of Venezuela. You can submit felt reports to the University of the West Indies Seismic Research Centre or the United States Geological Survey.
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).
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.
The Venezuelan Foundation for Seismological Research (FUNVISIS) also recorded this quake at a magnitude 6.0 (Mw) at a shallow depth of 5.0 kilometers.
The European-Mediterranean Seismological Centre (EMSC) also recorded this quake at a magnitude 5.9 (M) at a shallow depth of 10.0 kilometers.
Earthquakes in this area of Guyana are rare. According to the USGS and EMSC, only three other quakes have occurred in this area, deeper and of a smaller magnitude than Sunday afternoon’s quake.
Because there are no nearby plate boundaries, this seismic event is considered an intraplate earthquake within the South American Plate. The term intraplate earthquake refers to a variety of earthquake that occurs within the interior of a tectonic plate; this stands in contrast to an interplate earthquake, which occurs at the boundary of a tectonic plate.
About 5% of earthquakes take place within a plate, away from plate boundaries. These intraplate events are caused by stresses within a plate. Since plates move over a spherical surface, zones of weakness are created. Intraplate earthquakes happen along these zones of weakness. The seismic events may take place along ancient faults or rift zones.
Earthquakes *cannot* be predicted – meaning the precise time, date, magnitude, depth, etc. cannot be known ahead of time based on current research and technology.
In Guyana, earthquakes are a rare phenomenon but certainly not unheard of. In the Eastern Caribbean, however, these seismic events are far more frequent. Earthquakes of this magnitude, up to M8.0 and greater, are possible across the Lesser Antilles 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.