5:34 AM – Light Earthquake Northeast of Anguilla

At 5:34 AM Wednesday 13th May 2020, a light (preliminary) Magnitude 4.3 (Md) earthquake struck 149 km NNE of Basseterre, Saint Kitts and Nevis, 174 km NNW of Saint John’s, Antigua and Barbuda and 275 km NNW of Point-à-Pitre, Guadeloupe.

UWI SRC’s preliminary solution for the M4.3 earthquake at 5:43 AM Wednesday 13th May 2020

This event occurred at a preliminary depth of 10 Kilometers. This information is preliminary from the U.W.I. Seismic Research Centre, the authority for seismic and volcanological information in the Eastern Caribbean. Quake parameters such as location, depth, and magnitude may change upon review from a seismologist at the SRC.

This event has not been 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:

  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.

Though the University of the West Indies Seismic Research Centre’s solution remains preliminary, it’s the authoritative information for our region. The Centre not only as access to other seismic networks in the area, but their own dense network of seismometers and accelerometers to determine more precise and accurate quake parameters for seismic events in our region.

Nearly all international seismic monitoring agencies do not receive seismic data from FUNVISIS or UWI SRC. This means that in most cases, with reporting stations mainly north of T&T, the epicenter of quakes nearly always have a northward bias when it comes to latitude and longitude of a quake. It is also important to note that there is no exact location of a quake, as these seismic events occur due to a slip across a fault.

No matter how dense the seismic network is, there is always uncertainty which by the density of stations is reduced but never eliminated. When a solution is produced, the longitude and latitude are generated. All processing algorithms also provide the small and big axis of the eclipse with that location in the center, hence the location of an earthquake is not one point on the earth, but an area defined by those axes.

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.

Seismicity in this area is not uncommon, with 23 quakes occurring with 20 kilometers of the epicenter of this quake since the 1970s. The strongest events occurring within this 20-kilometer were two magnitude 5.0 quakes, occurring on February 21st, 1970, and November 27th, 1967. All other quakes in the past have generally registered below magnitude 5.0. Depths of earthquakes in this area are variable with quakes occurring up to 115-kilometer depth within the subducting slab of the North American plate under the Caribbean plate.

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.

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