Behind the Tremors: Understanding What Triggered Venezuela’s Deadly Quake

Caracas: Two powerful earthquakes that struck several areas of Venezuela, including the capital, Caracas, on Wednesday evening, proved particularly dangerous, causing numerous buildings to collapse. According to the US Geological Survey (USGS), a 7.2 magnitude earthquake struck first, followed just 39 seconds later by a powerful 7.5 magnitude tremor.

When and where did the earthquake occur?

According to the US Geological Survey (USGS), the first quake, measuring 7.1, was centered west of the community of Morón, located on the country's Caribbean coast, about 168 kilometers from Caracas. 

A few minutes later, a second, even larger, magnitude 7.5 earthquake struck, with a depth of 10 kilometers. The epicenter was 16 kilometers southwest of Morón. These tremors caused widespread devastation throughout the region. People took to the streets, building walls collapsed, and clouds of dust were seen rising.

Interior Minister Diosdado Cabello said that the tremor was felt in several states, with significant damage particularly in the Altamira area of  Caracas. He urged people to stay outdoors and be cautious of aftershocks.

Why did the earthquake happen?

Earthquakes are caused by the movement of the Earth's tectonic plates. Venezuela lies on the boundary between the Caribbean Plate and the South American Plate. The Caribbean Plate is moving eastward relative to the South American Plate at a speed of about 20 millimeters per year. 

This region is primarily a transform boundary, where plates slide past each other, such as the San Sebastian and El Pilar fault systems. When plates become stuck and stress builds up, sudden slippage occurs, causing earthquakes.

This time, the earthquake were shallow (10-13 km deep), so their impact was greater. Shallow earthquakes produce more vibrations at the surface. This region has been active for centuries. 

This doublet event (a foreshock followed immediately by a mainshock) released energy, a result of the region's complex geological structure. Subsidiary faults in the NW-SE direction are also active here, producing strike-slip motion.

What is the situation in Caracas?

In Caracas, people ran out of the shaking buildings. In many places, walls collapsed, leaving furniture visible from the street. Clouds of dust and collapsed buildings spread panic. Minister Cabello said some people were injured and urged people to clear the way for ambulances. He urged special care for children and the elderly.

Rescue teams are active, but the threat of aftershocks remains. This incident highlights the vulnerabilities of the country's aging buildings and earthquake-resistant infrastructure. Venezuela is already facing economic challenges, and relief and reconstruction will be a significant challenge.

What about Tsunami warning?

The US Pacific Tsunami Warning Center issued a tsunami alert for Puerto Rico and the Virgin Islands. Shallow-sea earthquakes can shake the ocean floor, creating large waves of water (tsunamis). This time, the epicenter was near the Caribbean coast, so nearby islands and coastal areas of Venezuela were at risk. The alert stated that sea level fluctuations and strong currents could occur.

However, the alert was later canceled because no major tsunami occurred. Tsunamis don't always occur; they depend on how shallow the earthquake was, the direction of the fault, and the extent of the seabed impact. This event demonstrated the importance of preparedness, especially in the Caribbean region, which is home to many small and large islands.