The 2003 Colima Earthquake and Regional Geology

The magnitude 7.6 earthquake that struck 16 km south-southwest of Cuyutlán, Mexico, on 22 January 2003 at 02:06 UTC originated at a depth of 24 km. This event remains one of the strongest recorded in the region since 2000 and was centered near the Pacific coast of Colima state. Cuyutlán lies within the Mexican subduction zone, where the Rivera Plate converges with and descends beneath the North American Plate. This tectonic setting produces frequent moderate-to-large earthquakes along the plate interface. The 2003 rupture occurred on the shallow portion of the megathrust, consistent with the area's history of interface events. The local geology features a narrow continental shelf, steep coastal slopes, and sedimentary basins that can amplify ground motion. Colima has experienced repeated strong shaking throughout recorded history. Notable predecessors include the great earthquakes of 1932 and 1941, both of which generated significant coastal damage and tsunamis. The 2003 event produced intense shaking across Colima and adjacent Jalisco, triggering landslides in the mountainous interior and liquefaction along low-lying coastal plains. Although the hypocenter was offshore, the proximity to populated centers resulted in structural damage to unreinforced masonry and older buildings. Post-event studies confirmed that the rupture propagated along a segment of the subduction interface previously identified as locked. Aftershock activity clustered both up-dip and down-dip of the mainshock, outlining an area roughly 100 km in length. No surface rupture was observed onshore, as expected for an offshore thrust event. The broader region continues to exhibit elevated seismic hazard. Ongoing convergence at rates of approximately 2–4 cm per year sustains the potential for future large earthquakes. Volcanic activity at Volcán de Colima, located roughly 150 km inland, is driven by the same subduction process and adds another layer of geologic risk through ash fall and lahars. Modern seismic networks operated by Mexican institutions have improved real-time monitoring since 2003, allowing faster characterization of similar events. Building codes in Colima now incorporate stricter seismic provisions, reflecting lessons from the 2003 shaking distribution.

References

USGS Earthquake Catalog Servicio Sismológico Nacional (Mexico) Global CMT Project subduction zone studies published in Geophysical Research Letters