The 2018 Carúpano Earthquake and Northeastern Venezuela Seismicity

On 21 August 2018 at 21:31 UTC, a magnitude 7.3 earthquake struck 40 km east-northeast of Carúpano in Sucre state, Venezuela. The event occurred at a depth of 146.8 km, placing it well within the intermediate-depth seismic zone beneath the Caribbean–South American plate boundary.

Northeastern Venezuela lies at the southeastern margin of the Caribbean plate, where the oceanic lithosphere of the Atlantic subducts northwestward beneath the continental South American plate at rates of approximately 2 cm per year. This convergence produces the Lesser Antilles volcanic arc to the north and a broad zone of strike-slip and thrust faulting onshore. The El Pilar fault system and associated structures accommodate much of the lateral motion, while deeper seismicity reflects ongoing slab descent.

Intermediate-depth earthquakes like the 2018 event typically originate within the subducting slab, where phase changes and dehydration reactions generate brittle failure. The focal depth of 146.8 km is consistent with this environment and explains the limited surface damage despite the magnitude; most energy was released below the brittle upper crust.

Instrumental records indicate that this was the only magnitude 7 or greater earthquake in the immediate region since 2000. Earlier historic events, including damaging shocks in 1929 and 1766, demonstrate that the area has experienced strong shaking, yet the 2018 earthquake remains the largest instrumentally recorded since the start of the twenty-first century.

Post-event analysis by regional networks confirmed aftershock activity concentrated at depths greater than 100 km, further supporting a slab-related origin. No significant surface rupture was observed, consistent with the depth and focal mechanism.

References

USGS Earthquake Catalog
Global CMT Project
Venezuelan Foundation for Seismological Research (FUNVISIS) annual reports