At 7:21 PM Sunday 24th January 2021, a preliminary moderate Magnitude 5.5 (Md or Mt) earthquake occurred 174 km NW of Basseterre, Saint Kitts and Nevis, 192 km E of Fajardo, Puerto Rico and 210 km E of Humacao, Puerto Rico.
This event occurred at a depth of 112 Kilometers. This information (above) is preliminary by the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean. This information may change when additional data is processed by a seismologist.
This post will be updated when additional information is provided by UWI SRC.
This event was widely reported felt across the Leewards and the western Greater Antilles, including the British and U.S. Virgin Islands, St. Kitts and Nevis, Anguilla, St Martin, St. Barthelemy, Antigua and Barbuda, and surrounding islands. You can submit felt reports to the University of the West Indies Seismic Research Centre.
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 United States Geological Survey places this quake in a similar location to the UWI SRC, at a slightly weaker magnitude at M5.2, at a depth of 111.2 KM.
The European-Mediterranean Seismological Centre places this quake in a similar location to the UWI SRC, at a depth of 100 kilometers and a magnitude of 5.2.
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.