Wednesday, January 29th 2020, 6:30 am - This is the first Magnitude-7.0 or stronger earthquake in 2020
A powerful Magnitude-7.7 earthquake struck 125 kilometres NNW of Jamacia with a relatively shallow depth of 10 kilometres at 2:10 p.m. EST. on Tuesday, according to the U.S. Geological Survey (USGS).
Earthquakes of this magnitude are extremely hazardous and have the potential to collapse buildings and cause extensive damage. In the case of this quake, the USGS estimated "moderate shaking" was felt on parts of Cuba and Jamaica, but the offshore location of the epicentre lessened its damaging impact.
At least a dozen smaller quakes and aftershocks, including a Magnitude-6.1 about 50 km southeast of the Cayman Islands, have been reported since the initial major earthquake. The quake reportedly ripped open sinkholes in the Cayman Islands, but did not do serious damage to people or to property.
A press release from the Office of Disaster Preparedness and Emergency Management of Jamaica said at least two parishes in Western Jamaica reported structural damage to buildings, and one school was closed due to concerns over structural weakness.
Some high-rise buildings in Miami, Florida evacuated after shaking was felt across the downtown area, nearly 900 km to the north. Minor shaking was reported as far north as St. Petersburg, according to local media.
Aside from the strength of the quake, part of the reason the shaking may have been more widely felt is due to its location, along a fault running between the North American and Caribbean tectonic plates. The crust under the northern Caribbean Sea and eastern North America is very efficient at transmitting earthquake energy (seismic waves), allowing quakes to be felt more widely east of the Rockies.
The NWS Pacific Tsunami Warning Center issued tsunami alerts for coasts around the Caribbean, including Cuba, Mexico, Jamaica, and Honduras, and later reported a small tsunami signal (roughly 0.1 m in height) might have been observed at a gauge in the Cayman Islands. The Center ended all tsunami statements shortly before 5 p.m. eastern time, saying the threat had passed. The type of fault -- known as a transform boundary, where plates are sliding past one another, rather than dipping beneath or riding above -- isn't typically associated with tsunamis, although they are possible. Most tsunamis are generated by earthquakes along subduction zone faults, where the edge of one plate is diving down beneath another.
Here is the latest from the @CityofMiami EOC regarding the effects felt in #Miami related to the 7.7 magnitude #earthquake that hit near Cuba and Jamaica. https://t.co/4rtkrFsKOVMayor Francis Suarez on Twitter
Evacuated building in Miami after Jamaica earthquake. https://t.co/0WWdUy7auOJohnBelski on Twitter
@OfficialJoelF Downtown Miami. I was in the 27th floor at my work. My desk and window was like moving.Steve on Twitter
The Technological University of Havana José Antonio Echeverría experienced damage after the earthquake. Credit: Ernesto Villegas
Damage from apparent liquefaction has also been reported on Grand Cayman, as seen in the images below. During an earthquake, shaking can temporarily make wet, sandy soil lose strength and behave like a liquid.
Cayman Islands after the earthquake 1/2 https://t.co/qnnXLdSSOa𝑅𝒾𝒸𝒽 𝒜𝓊𝓃𝓉𝒾𝑒 𝑀 on Twitter
Cayman island after earthquakes truck Caribbean Jamaica and Cuba mostly affected #earthquakeKheno Campbell® on Twitter
The Cayman Islands are literally larger versions of Maiden Cay. https://t.co/BEjNEOhR0pHurtquake 🌏 🇯🇲 on Twitter
This is the first earthquake with a magnitude greater than 7.0 in 2020. Earthquakes of Magnitude 7.0 or higher are uncommon; typically, there are fewer than 18 times per year, according to the Incorporated Research Institutions for Seismology.
The last time that Jamaica experienced a Magnitude 7.0 or higher earthquake was over 300 years ago in 1692 when a 7.5-Magnitude tremor caused around 5,000 deaths. This earthquake is the sixth most powerful earthquake that the Caribbean has experienced.