HAZ-2011-01 Preliminary Damage Report of the August 22, 2011 Mw 5.3 Earthquake near Trinidad, Colorado

A brief preliminary report compiled within 24 hours of the largest seismic event in the preceding 44 years in Colorado, it is illustrated with many detailed images of the ensuing damage. Additional information on this earthquake is available on RockTalk: Case Study: The Trinidad, Colorado Earthquakes. Digital PDF download. HAZ-2011-01D

Supersedes OF-11-06.

From the report:

At 11:46 PM MDT on August 22nd, 2011, a Mw 5.3 earthquake was recorded by U.S. Geological Survey seismometers and located 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.

On the morning of August 23rd, the Colorado Geological Survey dispatched geologists to the area to document the damage related to the largest earthquake in Colorado within the last 44 years. Locations with observed structural damage included (from most severe to least): Segundo, Valdez, Cokedale, and Trinidad. The following sections highlight the damage and witness testimonies documented by the CGS at each area.