Magnitude 7.6 earthquake strikes offshore fault near the Cayman Islands

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A relatively shallow, left-lateral strike-slip event struck on a fault zone that bounds the Caribbean plate.
 

By Ross S. Stein, Temblor, Inc., and Shinji Toda, Tohoku University
 

At 6:23 p.m. local time, a magnitude 7.6 earthquake in the Caribbean Sea struck north of Honduras, near the Cayman Islands (Figure 1). The left-lateral strike-slip earthquake’s epicenter was about 130 miles (209 kilometers) southwest of George Town, the capital city of the Cayman Islands. The remote event fortunately caused no damage or injuries as of this writing.

According to the U.S. Geological Survey’s finite fault model, the rupture was about 60 kilometers long.
 

Figure 1. Map of Caribbean plate faults. Earthquakes from the U.S. Geological Survey. Credit: Temblor, CC BY-NC-ND 4.0
Figure 1. Map of Caribbean plate faults. Earthquakes from the U.S. Geological Survey. Credit: Temblor, CC BY-NC-ND 4.0
 
 

This transform fault zone has ruptured in a half dozen shocks with magnitudes greater than or equal to 7 since 1900. Saturday’s earthquake ruptured the offshore section, called the Swan Islands Fault Zone. The most destructive prior earthquake was the 1976 magnitude 7.5 Guatemala earthquake, which struck the onshore Motagua fault that crosses the country, contributing to its seismic hazard.
 

Figure 2. Coulomb stress transfer calculations for the 2025 magnitude 7.6 earthquake that struck near the Cayman Islands in the Caribbean. Credit: Temblor, CC BY-NC-ND 4.0
Figure 2. Coulomb stress transfer calculations for the 2025 magnitude 7.6 earthquake that struck near the Cayman Islands in the Caribbean. Credit: Temblor, CC BY-NC-ND 4.0

 

Here, we use Coulomb Stress calculations to determine how stress has been transferred as a result of Saturday’s earthquake (Figure 2). We show that the rupture brings the adjacent portions of the Swan Islands fault closer to failure. So, aftershocks, and potentially progressive mainshocks, are likely in these sites over the next days to decades. The nearby rift that connects the Swan Islands fault to the Oriente fault — which sits to the north and runs parallel — also appears promoted toward failure. Due to its short extent, it could be the site of smaller shocks in the future.
 

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