The 2018 M7.5 Earthquake Northeast of Honduras

On January 10, 2018, at 02:51 UTC, a magnitude 7.5 earthquake struck approximately 203 km north-northeast of Barra Patuca, Honduras, at a depth of 19 km. This event stands as the sole strong earthquake (M7.0 or greater) recorded in the immediate region since January 1, 2000. The earthquake occurred within the Caribbean Plate's northern margin, where oblique convergence and transform faulting dominate. The Swan Islands Transform Fault and associated structures accommodate left-lateral shear between the Caribbean and North American plates. At 19 km depth, rupture likely occurred on a strike-slip or oblique-slip fault within the oceanic lithosphere of the Cayman Trough system. Such intermediate-depth events reflect the complex plate-boundary tectonics that extend from the Middle America Trench eastward into the Caribbean Sea. Honduras and its offshore waters have experienced recurrent seismicity tied to this plate-boundary regime. Historical records document damaging events in 1934 and 1982, both linked to the same transform system. The 2018 earthquake released accumulated strain along a segment that had remained relatively quiescent in the instrumental era, highlighting the irregular recurrence intervals characteristic of Caribbean transform faults. No significant foreshock activity was reported in the days preceding the mainshock. Aftershock sequences remained modest, consistent with the event's strike-slip mechanism and the relatively cool, brittle oceanic crust at the hypocentral depth. Regional seismic networks operated by Honduras and neighboring countries recorded the event clearly, aiding rapid assessment of ground-motion distribution across the Honduran platform and the Nicaraguan Rise. The geological framework of northeastern Honduras comprises Cretaceous to Tertiary sedimentary and volcanic rocks overlying older Caribbean basement. Offshore, the seafloor morphology reflects long-term transform motion, with linear ridges and pull-apart basins aligned parallel to the Swan Islands Fault. Updated bathymetric compilations confirm these structural trends continue uninterrupted through the epicentral area. Seismic hazard assessments for the Caribbean margin continue to incorporate the 2018 event as a calibration point for maximum credible magnitudes along the Swan Islands system. Ongoing geodetic monitoring with GPS stations on the Honduran mainland and the Bay Islands measures contemporary strain accumulation rates that align with long-term plate-motion models.

References

USGS Earthquake Catalog (event page for 2018-01-10 M7.5 Honduras) Global CMT Catalog (moment tensor solution for 2018 Honduras earthquake) Caribbean tectonic framework summaries from the Incorporated Research Institutions for Seismology (IRIS)