At 5:28 PM Friday 3rd April 2020, a preliminary Magnitude 4.2 (Md or Mt) earthquake occurred 161 km NW of Basseterre, Saint Kitts and Nevis, 238 km NW of Saint John’s, Antigua and Barbuda and 252 km E of Fajardo, Puerto Rico.
This event occurred at a shallow depth of 5.0 Kilometers. This information (above) 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 not reported felt at the time of posting. Based on its depth, and proximity to Anguilla, St. Martin, and Sint Maarten, felt reports are expected. 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).
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.
Seismicity in this area is not uncommon, with 23 quakes occurring with 20 kilometers of the epicenter of this quake since 1940. The strongest event occurring within this 20-kilometer area was a magnitude 5.6 on January 17th, 1941. All other quakes in the past have generally registered below magnitude 5.0, with the exception of a M5.2 quake on May 28th, 1966. Depths of earthquakes in this area are variable with quakes occurring up to 120-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.