At least two homes will have to be rebuilt in remote Southern Guyana following Sunday’s moderate M5.6 earthquake near the Guyana-Brazil border.
The United States Geological Survey has reviewed seismic data and has published their reviewed earthquake parameters, placing this quake at a very shallow depth of 7.2 kilometers, with the magnitude now at 5.6. According to the USGS, strong to very strong shaking was possible near the quake’s epicenter, with light to moderate shaking further from the epicenter.
Since the initial event at 3:05 PM Sunday, at least 10 aftershocks between magnitude 2.5 and 4.5 have occurred in the region. However, some communities in South Rupununi, which are close to the epicenter of the earthquake, still experienced continuous tremors over the last few days, according to the Guyana Chronicle.
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The strongest shaking was felt in the South Rupununi area, where several buildings and earthen surfaces were damaged. Speaking with the Guyana Chronicle, Regional Chairman of Region Nine, Brian Allicock, explained that the communities of Katoonarib, Sawariwau, and Aishalton were among those more seriously affected: a few houses collapsed, and some roads were cracked.
“What happened [on Sunday], that lasted for quite a while in Aishalton. The vibrations, very ugly vibrations, lasted for about one minute and it got a lot of people scared and houses were damaged.”
In the community of Katoonarib, which is approximately an hour’s drive away from Aishalton, Thomas related that there had been these intermittent tremors, which have been of much concern to the community.
Region 9 Authorities Respond
The authorities in Region Nine (Upper Takutu/Upper Essequibo) will assist in rebuilding two houses that were destroyed in the villages of Sawariwau and Katoonarib in Deep South Rupununi.
The Civil Defence Commission (CDC), in a statement on Tuesday, said it continues to monitor the impact of the earthquake. In the meantime, Regional Executive Officer Karl Singh informed the CDC that the region would assist in rehabilitating damaged homes. Construction materials were being deployed to the communities on Tuesday.
“Based on the assessments conducted across the Regions, the Upper Takutu-Upper Essequibo (Region 9) which shares a border with Brazil was hardest hit.”
The Regional Disaster Response System was activated, and assessments revealed damages to the two homes and a few earth surface cracks. The CDC stated that while the team was on the ground, loud rumbling sounds were heard about three times from different directions around the communities on Monday.
“There are no reports of loss of human lives. Residents reported that years ago this sound was heard, and it felt like “movement” of the earth,” the CDC said.
Meanwhile, the Regional Chairman, Bryan Allicock further revealed that the village of Sawariwau, which is closer to the Brazilian border, has been experiencing tremors for years.
The CDC will now be partnering with the Minister of Natural Resources to conduct further analysis, observation, and assessments to gain a comprehensive perspective of the Region’s susceptibility to seismic hazard.
The CDC is also in discussion with the Seismic Research Center of the University of the West Indies and the Caribbean Disaster Emergency Management Agency to provide technical support if the need arises. The result of these assessments could determine future actions, which can include but not limited to conducting earthquake preparedness and response planning, and training, evacuation drills, and exploring the possibility of developing earthquake-resilient infrastructure codes for that Region and, by extension, Guyana, the CDC stated.
Guyana is located in what is known as a stable continental region. This means that earthquakes are not expected to be frequent, devastating occurrences. However, it does not mean that Guyana is completely safe from earthquakes and should ensure that it plans well for such potentially devastating occurrences.
Because there are no nearby plate boundaries, this seismic event is considered an intraplate earthquake within the South American Plate. The term intraplate earthquake refers to a variety of earthquake that occurs within the interior of a tectonic plate; this stands in contrast to an interplate earthquake, which occurs at the boundary of a tectonic plate.
About 5% of earthquakes take place within a plate, away from plate boundaries. These intraplate events are caused by stresses within a plate. Since plates move over a spherical surface, zones of weakness are created. Intraplate earthquakes happen along these zones of weakness. The seismic events may take place along ancient faults or rift zones.
Earthquakes *cannot* be predicted – meaning the precise time, date, magnitude, depth, etc. cannot be known ahead of time based on current research and technology.
In Guyana, earthquakes are a rare phenomenon but certainly not unheard of. In the Eastern Caribbean, however, these seismic events are far more frequent. Earthquakes of this magnitude, up to M8.0 and greater, are possible across the Lesser Antilles 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.