January 2019: 67 Earthquakes Reported

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Over the course of January 2019, 67 earthquakes were reported by the Venezuelan Foundation for Seismological Research (FUNVISIS) & the University of the West Indies Seismic Research Centre (UWI SRC). It is important to distinguish between reported earthquakes versus recorded earthquakes, as this number is likely much higher. FUNVISIS publicly reports on recorded quakes larger than M2.5, whereas UWI SRC publicly reports on recorded quakes larger than M3.8, or smaller if a large population feels the quake.

Trinidad and Tobago, and the surrounding region is a very seismically active area. 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.

Of these 67 earthquakes in January 2019, 19 were larger than magnitude 3.8. and 26 were larger than magnitude 3.5.

This month recorded a higher than normal monthly total of earthquakes due to the M5.2 earthquake on January 7th 2019, and its subsequent aftershock sequence west of Trinidad, in the vicinity of Carúpano. 42 of the 67 earthquakes reported resulted from this earthquake and aftershock sequence. This activity occurred in a known earthquake zone where several small, conjugate faults interact with the main El Pilar Fault, triggering activity reminiscent of a seismic swarm.

The First Felt Earthquake of 2019

Magnitude M4.6 striking at 10:33AM 4th January 2019, widely reported felt across Northern Trinidad

At 10:33AM Friday 4th January 2019, a Magnitude 4.6 earthquake occurred 42 km NNW of Port of Spain, Trinidad and Tobago and 57.2 km NW of Arima, Trinidad and Tobago. This event occurred at a moderate depth of 40.0 kilometers. It was widely reported felt across Northern Trinidad and parts of Central Trinidad.

Based on the depth of this earthquake, it occurred just on the boundary of the Caribbean Plate and the subducting slab of the South American plate, within seismic zone 4.

The Largest Recorded Quake of January 2019

Magnitude M5.2 striking at 1:08AM 7th January 2019, widely reported felt across Northeastern Venezuela, with some felt reports across Western Trinidad

At 1:08AM Monday 7th January 2019, a Magnitude 5.2 earthquake occurred 14.9 KM SSE of Carúpano, Venezuela and 186.5 KM W of Port of Spain, Trinidad and Tobago. This event occurred at a moderate depth of 56.2 KM.

This event was reported felt across far western and southwestern areas of Trinidad, including Cedros and San Juan. Moderate to strong shaking was reported nearer to the epicenter in Carúpano, Río Caribe and Casanay Estado Sucre.

Please note that magnitude varies based on the reporting scientific agency. Other magnitudes are not incorrect, just different methodologies were used to arrive at the resulting magnitude. The USGS reported this earthquake at a shallower depth of 17.0 Kilometers and a magnitude of M4.6.

Based on the depth of this earthquake, it likely occurred in the seismic zone 2 along a rupture, albeit deep, on the El Pilar Fault, part of the Boconó-San Sebastian-El Pilar Fault system that runs across Northern Trinidad and Venezuela. This fault system is part of the larger South American plate moving parallel to the Caribbean Plate. This area typically has high seismicity. Strong earthquakes in this area have occurred in the past, with the largest being just over magnitude 7.0.

Other Quakes Larger than M3.8 Reported in January 2019

FAQ on January 2019 Earthquakes

If the general population didn’t feel the earthquake, why publish the information?

This is a common question or criticism from scientists, disaster preparedness officials and the general population alike. The intentions are not nefarious, but purely to educate. Time and time again, Trinbagoians take for granted lull periods between seismic events. Only when a strong to major quake strikes, then the general population remembers that they live in a seismically active area. In fact, the Paria Peninsula, northwest of Trinidad, is one of the most active seismogenic zones in the Eastern Caribbean. Earthquakes occur on a daily basis across T&T. The “Big One” can strike at any moment, without any prediction and has the potential to cause cataclysmic damage across the islands. However, with preparedness and awareness, we can become a earthquake-ready and earthquake-safe population.

Why does magnitude, depth and location vary between the USGS, UWI SRC & FUNVISIS?

Globally, earthquake monitoring agencies use different methods for processing earthquakes so often there are differences in the results. This is generally expected and accepted by the scientific community but can present some confusion for the general population.

The UWI Seismic Research Centre is the authoritative agency for seismic hazards in the English-speaking Eastern Caribbean and operates the widest and densest network of seismic stations in the region which, by extension, is likely to consistently yield the most accurate results for the islands under its area of responsibility, which includes Trinidad & Tobago.

The SRC is not currently being funded to operate a 24-hour facility, however the Centre has a courtesy, 24-hour response system since there are duty scientists who have agreed to be on call outside of working hours who may attend to events as they occur. In an effort to meet the public’s insatiable demand for more information within the shortest possible time frame, they have implemented an automated system which provides earthquake solutions often within minutes of the event and posts these to their social media accounts, usually well before other regional and international agencies. Results are reviewed by an analyst shortly thereafter and posted to their website.

There is usually a 10 km margin of error in latitude and longitude, but often tens of km in depth, between preliminary results and reviewed results (which is standard for monitoring agencies), magnitude tends to change as more data come to hand, even with manual processing.

Does an increase in the number small earthquakes decrease the chance of the “Big One” occurring?

Seismologists have observed that for every magnitude 6 earthquake there are about 10 of magnitude 5, 100 of magnitude 4, 1,000 of magnitude 3, and so forth as the events get smaller and smaller. This sounds like a lot of small earthquakes, but there are never enough small ones to eliminate the occasional large event.

It would take 32 magnitude 5’s, 1000 magnitude 4’s, OR 32,000 magnitude 3’s to equal the energy of one magnitude 6 event. So, even though we always record many more small events than large ones, there are far too few to eliminate the need for the occasional large earthquake. (Source: USGS)

If you have any questions, feel free to leave them in the comments below!

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