Northern Venezuela is no stranger to large, damaging earthquakes. But the pair that tore through the region on Wednesday ranks as a rare catastrophe — a one-two punch representing one of the most powerful tectonic events to strike there in the past century.

At 6:04 p.m. local time, a magnitude 7.2 temblor struck to the west of the capital city of Caracas; this was followed just 39 seconds later by a magnitude 7.5 rupture. So-called doublets are uncommon, but not vanishingly so. In September 2025, just southwest of Wednesday’s doublet, a pair of quakes (magnitudes 6.2 and 6.3) caused widespread damage to buildings and injured more than 110 people.

The extent of the devastation is not yet clear, and scientists may yet revise their estimates of the quakes’ strength. Over the coming weeks, researchers will gather reams of geologic data and build up a detailed picture of the twin temblors.

But they already have an idea as to why these quakes took place in such a remarkably short time and why they were so damaging. Here’s what they know so far about these catastrophic earthquakes, and what to expect in the days to come.

Why was one strong quake immediately followed by another?

During a sequence of earthquakes, the most powerful among them — in this case, the magnitude 7.5 event — is considered to be the main shock, which would make the magnitude 7.2 event the “foreshock.”

These two quakes together are known as a doublet, because of their back-to-back nature at nearly the same location and probably on the same fault, or a closely related group of faults. But Wednesday’s pair was peculiar.

“Most doublets don’t occur quite this close together in time,” said Brandon Bishop, a seismologist at Saint Louis University. “Delays of hours to a few days are much more common.”

The timing is almost certainly not a coincidence. “It is very likely that the first triggered the second one,” said Harold Tobin, the director of the Pacific Northwest Seismic Network at the University of Washington.

The ferocious seismic waves unleashed by the initial rupture may have convulsed an adjacent, locked-up section of the fault, which triggered the second quake. Although these two quakes might be considered separate events, “this could be regarded as one earthquake that went on for 50 seconds or so,” said Stephen Hicks, a seismologist at University College London in England.

Instead of a pause between the two events, it may be better to think of this disaster as a near continuous rupture that “cascaded into this bigger beast,” he added.

Why were these earthquakes so destructive?

Although a magnitude 7.2 event sounds just a little less severe than a magnitude 7.5 quake, this scale isn’t linear. According to scientists, the second quake released almost three times as much energy as the first.

Other factors conspired to make this doublet particularly devastating.

“Both earthquakes are relatively shallow,” said Dr. Bishop. That means that the potency of the seismic waves wasn’t much diminished by the time they coursed across the Earth’s surface.

The quakes took place in the Yaracuy Valley, which is filled with loose sediments — the very sort that amplify shaking. This led to landslides and even liquefaction, a temporary state in which soil behaves like a fluid.

And as the fault rupture moved eastward, in the direction of the capital city, Caracas “got a direct hit,” said Dr. Hicks.

Is this area prone to earthquakes?

This region is a messy geologic jigsaw puzzle. The Caribbean tectonic plate is moving eastward relative to the South American plate by less than an inch per year. In one section, the Caribbean plate has also been forced under the South American plate, causing parts of the latter to fragment.

Within a 155-mile vicinity of Wednesday’s earthquakes, there have been seven magnitude 6 or greater earthquakes in the past century. And around the epicenters of this week’s doublet, there are three known significant faults mapped out: the Boconó Fault, the El Guayabo Fault and the Morón Fault.

The magnitude 7.5 event appears closest to El Guayabo, while the magnitude 7.2 earthquake seems nearest to Morón. But with the uncertainties involved, all three are suspects — and more than one could have ruptured.

This complexity makes untangling the root cause of Wednesday’s quakes somewhat troublesome. But early indications are that the fault, or faults, that ruptured did so in a strike-slip fashion, meaning two blocks of the crust slipped in a side-to-side manner with respect to each other.

“Strike-slip faults tend to produce strong seismic shaking, especially near to and along the length of the fault that moved,” Dr. Tobin said.

“This is analogous to the East Anatolian Fault that devastated Turkey a few years ago, Haiti in 2010, or the San Andreas Fault,” he added.

Will there be any significant aftershocks?

They are already taking place. According to the forecasts by the U.S. Geological Survey, the region will be rattled by myriad smaller quakes (magnitudes 3 to 5) over the next week.

Within this time frame, there is a 24 percent chance of a magnitude 6 event striking the area, and a 3 percent chance of another magnitude 7 quake taking place.

“Normally, aftershocks occur most frequently right after a big one, then tail off exponentially over days to weeks to years,” said Dr. Tobin. That means the chaos and fear gripping the nation right now is likely to continue well into the future.