The 2 earthquakes that struck Venezuela are known as a 'doublet.' Here's what to know about them

By — Dánica Coto, Associated Press Dánica Coto, Associated Press Leave your feedback Share Copy URL https://www.pbs.org/newshour/science/the-2-earthquakes-that-struck-venezuela-are-known-as-a-doublet-heres-what-to-know-about-them Email Facebook Twitter LinkedIn Pinterest Tumblr Share on Facebook Share on Twitter The 2 earthquakes that struck Venezuela are known as a 'doublet.' Here's what to know about them Science Jun 25, 2026 5:54 PM EDT SAN JUAN, Puerto Rico (AP) — The two powerful earthquakes that struck Venezuela's northern coast, killing more than 180 people, were an event known as a "doublet." Grow your mind Subscribe to our Science Newsletter to explore the wide worlds of science, health and technology. Doublet earthquakes happen when a pair of similar-sized quakes hit close in location and time, according to the U.S. Geological Survey. On Wednesday evening, a 7.2 magnitude quake hit first, followed by a magnitude 7.5 just 39 seconds later. The deadly one-two punch toppled buildings in Venezuela's capital, Caracas and beyond. Some 1,500 people were injured and thousands were reported missing. The coastal region of La Guaira, which is north of Caracas, experienced some of the heaviest damage and casualties, officials said. How rare are doublets? While not as common as a typical earthquake where a main shock is followed by much smaller aftershocks, doublets can happen anywhere in the world, Christine Goulet, director of the USGS earthquake science center in California, told The Associated Press. Doublets indicate a complex fault structure, like the one in Venezuela. Known as the Bocono fault, it runs along the backbone of the Venezuelan Andes for about 300 miles (500 kilometers). A previous doublet — of magnitudes 6.2 and 6.3 — struck an area west of Caracas in September 2025, killing at least one person and injuring more than 100 others. Most of the damage was reported in the states of Zulia and Lara. What caused Wednesday's double earthquake? Most earthquakes occur along plate boundaries, which is where tectonic plates meet. A rupture where the Caribbean and South American tectonic plates meet unleashed the two quakes this week. The doublet occurred where the Caribbean plate, located north of Venezuela, moves eastward relative to the South American plate at an average rate of 0.79 inches (2 centimeters) a year. "It's a large displacement," Goulet noted. "It's on the order of the San Andreas fault." The movement was a shallow strike-slip faulting, which occurs when two blocks of rock slide past one another horizontally. That kind of movement is not more dangerous by default, Goulet said. READ MORE: At least 188 people are dead in Venezuela after 2 earthquakes rocked the country's north "A more vertical motion can be more damaging," she said, adding that other factors, including the length of the rupture, determine the amount of damage. The boundary between the Caribbean and South American plates is less active than others, said David Naar,