At 8:29 AM Saturday 14th August 2021, a major (preliminary) magnitude 7.2 earthquake struck the Haitian Peninsula approximately 12.2 KM NE of Saint-Louis du Sud, Sud, Haiti, 33.2 KM ENE of Les Cayes, Sud, Haiti, and 42.6 KM WSW of Miragoâne, Nippes, Haiti.
Though earthquake parameters are expected to change in the coming hours as more data comes to hand, this major earthquake struck at a depth of 10 kilometers, centered on land at 18.352°N 73.480°W.
According to the United States Geological Survey (USGS) and the European-Mediterranean Seismological Centre (EMSC), light to moderate shaking was reported across Jamaica, Cuba, Southeastern Bahamas, the Tucks, and Caicos and the Dominican Republic. Strong to severe shaking has been reported in Haiti, with violent shaking reported near the epicenter of the quake.
The Pacific Tsunami Warning Center, responsible for issuing tsunami threat messages for the Caribbean Region, stated in a Tsunami Information Statement at 8:38 AM, “Based on all available data, there is no significant tsunami threat from this earthquake. However, there is a very small possibility of tsunami waves along coasts located nearest the epicenter.”
However, in their second update, the Pacific Tsunami Warning Center is now warning that tsunami waves between 1.0 meters and 3.0 meters are possible. The PTWC advises “Actual amplitudes at the coast may vary from forecast amplitudes due to uncertainties in the forecast and local features. Maximum tsunami amplitudes on atolls or small islands and at locations with fringing or barrier reefs will likely be much smaller than the forecast indicates.”
In their final update, at 10:14 AM AST, the tsunami threat has passed for the area, though abnormal tidal fluctuations are possible over the next several hours near the quake’s epicenter.
Aftershocks have been reported felt in Haiti, with the largest so far occurring at 8:49 AM at a preliminary magnitude of 5.2.
According to the USGS, there high numbers of casualties are probable with significant damage likely.
Note that different seismic monitoring agencies use different methods, or several methods, for processing quake parameters across the globe. Each method has its limitations and will likely produce different results within the ranges of the data’s uncertainty. This is generally accepted within the scientific community.
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.
Seismic waves from the 8:29 AM Haitian earthquake are rolling across Trinidad and Tobago. These waves are too small to be felt, normal for large earthquakes and generally are only detected by very sensitive instruments (seismometers). pic.twitter.com/ldoIlegbhh— Kalain Hosein (@KalainH) August 14, 2021
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.