At 11:03 PM (local time) on Wednesday, September 28th, 2022, the United States Geological Survey recorded a strong magnitude 6.7 (Mi) earthquake in the South Atlantic Ocean.
The quake struck at a relatively shallow depth of 33.0 kilometers and was located at 60.6°S 20.0°W, approximately 2650.8 kilometers south-southwest of Tristan da Cunha, Saint Helena.
The Pacific Tsunami Warning Center issued a Tsunami Information Statement at 11:13 PM Wednesday advising that based on all available data, there is no tsunami threat to Caribbean Coasts from this earthquake.
There are four conditions necessary for an earthquake to cause a tsunami:
- The earthquake must occur beneath the ocean or cause material to slide within or into 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 a shallow depth – less than 70 kilometers below the surface of the Earth.
- The earthquake must cause vertical movement of the seafloor (up to several meters).
While conditions one, two and three were met, Wednesday night’s earthquake occurred along the South Sandwich Fracture Zone, a strike-slip boundary where the South American Plate and the Antarctic Plate slides past one another. Earthquakes along strike-slip fault generally do not create significant vertical movement.
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 range of the data’s uncertainty. This is generally accepted within the scientific community.
Read More
Earthquake Magnitude & Intensity
Can earthquakes be predicted or forecasted?
Earthquakes Near T&T
Trinidad and Tobago and the surrounding region are very seismically active. Across the Eastern Caribbean, over 2,200 earthquakes are recorded annually. Since 1990, the University of the West Indies Seismic Research Centre records an annual average of 280 earthquakes in the Trinidad and Tobago region (area bounded by 9.5°- 11.5°N & 59.5°W – 63.5°W). Of these 280 quakes, 50 of these seismic events are, on average, above magnitude 3.5.
Most earthquakes occur northwest of Trinidad in an area known as North of the Paria Peninsula, which has the second-highest seismicity in the Eastern Caribbean. According to the UWI SRC, approximately 65 events of magnitude 2.1 and above are located in the area annually.
However, the UWI SRC has said regional seismic and volcanic activity has been elevated for several years in their annual report for 2020 to 2021.
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 that great quakes (M8.0+) on the Richter Scale have occurred every century in the region. The probability of another event at that level is high since the last >M8.0 earthquake occurred in 1843. While it is impossible to say definitively when the next great quake would occur in the region, the time since the last one is now more than 170 years ago.
It is important to note seismic activity *cannot* be predicted – meaning the precise time, date, magnitude, depth, etc., cannot be known ahead of time based on current research and technology.
Now is the time to create or go over your earthquake preparedness plan and know what to do during, before, and after an earthquake.
Read More
In our region, earthquakes can strike at any time and any place, so it is important to know how to keep yourself safe when one strikes.
