On August 21, 2018 a magnitude 7.3 earthquake struck just off the northern coast of Venezuela, near Cariaco, Sucre. The earthquake is thought to be the largest in the country since the 1900 San Narciso earthquake. It prompted evacuations in Caracas, and caused shaking in Colombia, Guyana, Brazil, Grenada, Dominica, Barbados, St. Vincent and the Grenadines, St. Lucia, and Trinidad and Tobago, the last of which also suffered damage and brief phone and power outages from about 100 miles away. A tsunami was not expected, though the Pacific Tsunami Warning Center warned of wave potential, and an alert had been broadcast for tsunami waves along coastlines. In terms of damage, concrete fell from the unfinished Tower of David skyscraper, blocking the sidewalk and closing traffic.
According to the governor of Sucre State, there were initially no reports of fatalities in the area. Though several sources from the Venezuelan government reported no injuries, there were reports of injuries in a shopping centre in Cumaná, close to the epicentre, when an escalator collapsed. Later, five people were confirmed dead, after heart attacks during the quake from shock. Interior Minister Néstor Reverol maintained that there were no fatalities.
The earthquakes follow a series of related earthquakes two weeks earlier in neighbouring Colombia, including brief shakes of 6.1 and 5.8 magnitude on August 7.
Earthquake
The epicentre is reported to be just east of Carúpano, and at a depth of . The Venezuelan capital, Caracas, is around from this site, and still shook, as did Bogotá, the Colombian capital nearly away. The United States Geological Survey reported the quake as 7.3 (after an initial report of 6.8), though the Colombian Geological Service reported it as 7.0. The Venezuelan Interior Minister Néstor Reverol reported that the earthquake was 6.3. The U.S. Pacific Tsunami Warning Center instead reported the quake as 7.4.
Venezuela's coast at Cariaco lies on the El Pilar fault of the Caribbean and South American plates, with the latter subducting under the former when the fault turns perpendicular to the coastline. Though Caracas is a long distance from the epicentre, because it is still on the fault line at the San Sebastian fault the tremor was still quite powerful. A seismologist from the University of Southampton said that the two plates usually experience "horizontal differential motion" (the Caribbean plate moves eastward, the South American plate moves westward, and they strike and catch against each other) but that the earthquake being so deep indicated that it was not "directly related to transform faulting [or] strike-slip faulting", suggesting that the quake may have been caused by the "edge of the South American plate that is subducting under the Lesser Antilles arc" being involved.
CNN reported that someone based in Güiria, 43 miles from the epicentre, felt three aftershocks. A seismograph at Virginia Tech, a university in the northern United States, registered the earthquake. The University of the West Indies Seismic Research Centre recorded aftershocks throughout the region from shortly after the main quake.
Witnesses and news sources report that during the quake, people were reluctant to leave some buildings, in particular banks because they were "desperate to withdraw the limited notes they're authorised to claim in the cash-strapped country" so "didn't want to leave".
Irregularity
Multiple experts remarked on how the seismological activity that caused the earthquake was unusual. Juan Cigala, from the Seismology Department of the Iquique Emergency Center, Mexico, explained that the earthquake was "an exceptional event" and also "expressed surprise" at the subsequent earthquake as well as aftershocks of over 4.0 magnitude, something that "hasn't happened before". He summarised that "the Earth is behaving in a different way".
Cigala also mentioned that the direction of the forces from the plates contacting was unusual, explaining why the earthquake was felt for thousands of miles in multiple directions. He added that this, as well as the continual plate movement since the earthquake, means there will "continue to be telluric events in the area", and a likelihood of more quakes.
Damage
Bogotá International Airport was briefly closed to check for runway damage.