The Trinidad area has a history of natural earthquakes and lies within the Raton Basin. For more information on idividual events see the Earthquake and Late Cenozoic Fault and Fold Map Server.

In 1966, a 4.5 magnitude earthquake was reported northeast of Trinidad. In 1973, a swarm of four earthquakes ≤4.2 magnitude was reported west of Trinidad. In 1983, a magnitude 3.2 earthquake was reported northeast of Trinidad. In 1996, a series of three earthquakes ≥3.2 magnitude hit northeast of Trinidad. In 2001 an earthquake swarm was observed . Activity ceased for a decade. In 2011 an earthquake swarm occurred with significant damage in surrounding communities. A complete report is available at: Trinidad, Colorado Earthquakes

Magnitude 4.6 Earthquake - Segundo, Colorado - September 5, 2001 @ 10:52 AM

Image:  V. Matthews. Click image to enlarge

This Mw 4.6 earthquake caused minor damage.  The epicenter was ultimately determined to be near the town of Segundo (13 miles SW of Trinidad, Colorado).  

This earthquake activity near Trinidad resulted in investigation and research by the Colorado and US Geological Surveys.  Because of this seismic event and the subsequent earthquake swarm, the Colorado Geological Survey acquired a permanent seismograph station east of Trinidad.  This instrument is also connected to the National Earthquake Information Center network.


Magnitude 5.3 Earthquake  - Trinidad, Colorado - August 22, 2011 @ 11:46 PM

Image: M. Morgan Click image to enlarge

A Mw 5.3 earthquake was recorded by U.S. Geological Survey seismometers, locating the epicenter approximately 9 miles (+/- 7.8 miles) WSW of Trinidad, Colorado.

Early reports by local news media indicated that significant damage to buildings had occurred in the towns of Segundo and Valdez, 15 miles west of Trinidad on Colorado State Highway 12. Prior to the Mw 5.3 event, three smaller events were also recorded in the same vicinity, the largest being an Mw 4.6 event at 5:30 PM MDT.

The Colorado Geological Survey investigated both of these events and provided scientific information for affected communities.  In both occurrences, CGS collaborated with, and cooperated with, the Colorado Division of Emergency Management, the Colorado Oil and Gas Conservation Commission, and the National Earthquake Information Center (USGS).

References:
Earthquake Rock Talk (Matthews, 2002) 
Investigation of an Earthquake Swarm - Trinidad, Colorado, August-October 2001 (Mark E. Meremonte and others, 2002)
Preliminary Damage Report of the Mw 5.3 Earthquake in Trinidad, Colorado, August 23, 2011 (Morgan and Morgan, 2011)


Colorado Geological Survey