Two deadly earthquakes rocked northwestern Venezuela on June 24, 2026. In a remarkable sequence, a magnitude 7.2 foreshock was followed 39 seconds later by a magnitude 7.5 mainshock (the two separate USGS Shakemaps are shown below). The region has had many large historical earthquakes, so these events were not especially surprising. However, the high numbers of fatalities and injuries, along with widespread damage that includes the collapse of hundreds of buildings—among them a 22-floor residential high-rise — are staggering and tragic.

Shakemap from USGS for the magnitude 7.2, maximum intensity 8.767 earthquake

Northern Venezuela is within the broad boundary between the Caribbean and South American tectonic plates. The pair of major earthquakes originated within this boundary zone near the San Sebastian fault system. At this location, the Caribbean plate is moving eastward relative to South America at a rate of about 0.8 in/yr (20 mm/yr). Shallow strike-slip motion, where blocks of crust slip horizontally past each other, was recorded for both earthquakes. Modeling by the US Geological Survey shows that the 7.5 earthquake ruptured along a fault approximately 109 mi (175 km) long by 12 mi (20 km) wide.

Shakemap from USGS for the magnitude 7.5, maximum intensity 9.046 earthquake

On the Volcano Café website, a post by Albert, The 2026 Venezuela earthquakes, has excellent details about the tectonic setting and fault systems in the region, including many maps. Highly recommended reading!

Many smaller aftershocks have followed the June 24 earthquakes, including one of magnitude 4.8 on June 27. Typically, large mainshocks are followed by smaller aftershocks; often a smaller foreshock occurs within hours before a mainshock. When stress in the Earth’s crust is relieved by an earthquake, it changes the stress on nearby faults, often triggering aftershocks or another large earthquake. Several recent earthquakes in California show this pattern, including the 1992 Landers earthquake in Southern California, magnitude 7.3, that was followed about 3 hours later by a magnitude 6.5 earthquake in Big Bear Lake, 22 miles (35 km) to the east.

The strike-slip motion of the two Venezuela earthquakes occurs at fault settings in other parts of the world. California’s major fault systems, including the San Andreas and Hayward, have strike-slip motion. Several separate fault segments of varying lengths that are offset from each other are characteristic of strike-slip fault zones. If more than one segment ruptures, it can trigger another segment to break. This can double the duration of ground shaking and bring more structures to the point of collapse. An earthquake sequence like the two that occurred in Venezuela is rare, nonetheless, there is a low probability that this type of earthquake series could take place in California.

There is a practical lesson here: if you live in earthquake country, a moderate or even large earthquake could be a foreshock, and aftershocks could continue to cause damage during the days after the shaking from a mainshock ends.

 

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SOURCES

USGS information on June 24 and 27 earthquakes, Venezuela,   https://earthquake.usgs.gov/earthquakes/eventpage/us6000t7zc/executive https://earthquake.usgs.gov/earthquakes/eventpage/us6000t7zp/executive ; https://earthquake.usgs.gov/earthquakes/eventpage/us6000t8q8/executive

Shakemap from USGS for the magnitude 7.2, maximum intensity 8.767 earthquake; Wikimedia

Shakemap from USGS for the magnitude 7.5, maximum intensity 9.046 earthquake; Wikimedia