Rare Back-to-Back Major Earthquakes Prompt National Emergency in Venezuela
Venezuela has declared a national state of emergency after two powerful earthquakes, measuring 7.2 and 7.5 magnitude respectively, struck just 39 seconds apart this past Wednesday.
This unusual geologic event, known as a seismic doublet, is extremely rare. Even so, similar occurrences have been documented across multiple regions worldwide, and ongoing research into these events helps scientists expand their understanding of how tectonic stress shifts through the Earth’s crust and how separate geological faults interact.
Per data from the U.S. Geological Survey (USGS), both quakes had their epicenters northwest of the Venezuelan town of Yumare, near the city of Morón, and roughly 160 kilometers (99 miles) west of the national capital Caracas. The two quakes struck at depths of 20.3 kilometers and 10 kilometers respectively, and shaking was felt across most of northern Venezuela as well as in several neighboring Caribbean countries.
This sequence is classified as a severe seismic doublet: a phenomenon defined as two similarly sized earthquakes hitting nearby locations almost at the same time. According to USGS estimates, the probability that an earthquake will be followed by a larger quake in the same region within a seven-day window is only around 5 percent.
One of the most impactful seismic doublets in recent modern history occurred roughly three years ago across Turkey and Syria, where a 7.6-magnitude quake was followed shortly by a 7.8-magnitude event. Research into that disaster concluded the doublet formed after tectonic stress built up over more than two centuries along the fault that produced the first quake. When that fault ruptured, the released stress shifted to an adjacent fault, triggering the second major rupture in rapid succession.
How Do Seismic Doublets Form?
Experts believe a nearly identical process unfolded in Venezuela. Mark Allen, a professor of earth sciences at Durham University, explained in comments shared by SMC Spain that “it is likely that the first earthquake caused a segment of the fault to rupture and transferred the stress to another fault, which in turn ruptured, triggering the second earthquake.”
Allen added that the unique geological traits of the epicenter region played a key role in the event. “The events appear to have taken place at the plate boundary between South America and the Caribbean. In this region, the plates move laterally relative to one another, similar to what occurs along the San Andreas Fault in California,” he said.
This tectonic setting is prone to strike-slip earthquakes, which form when two blocks of the Earth’s crust slide horizontally along a fault and suddenly release stress that accumulated over long periods of time. Unlike subduction earthquakes, which occur when one tectonic plate slides beneath another, strike-slip earthquakes typically originate much closer to the Earth’s surface. Because the energy released travels a shorter distance before reaching populated areas, this creates more intense shaking and a higher risk of widespread damage.
Allen warned that these same conditions create ongoing hazard for the Caracas region: “there is a risk of further earthquakes (aftershocks) in the Caracas region. The Venezuelan capital is located in an area prone to seismic activity, and it is possible that local faults have been subjected to additional stress following the recent events.”
This warning aligns with USGS assessments, which note that after major earthquakes of this scale, seismic activity can continue for days, weeks, or even longer. While aftershock frequency drops over time, powerful damaging events remain possible.
As of the latest official counts, the two Venezuelan earthquakes have killed at least 164 people and injured nearly 1,000 more. USGS projections estimate the final death toll could reach as high as 10,000 to 100,000, driven by factors including the intensity of the quakes and the inherent vulnerability of the region, from poor construction quality to high population density in affected areas.
This article was adapted from original reporting published by WIRED en Español, and has been translated and edited from the original Spanish version.
