The quake was centered about 10 miles west of Trinidad and 20 miles northwest of Raton, New Mexico on the northern side of Picketwire Valley, on the between Butte and Reilly Creeks, near Cokedale. (See a topoZone location map). The focal depth for the quake was fixed at 5.0 km beneath the surface for quick processing and we do not have a fault plane solution for this event as of yet.

Foreshocks and aftershocks
A foreshock registering M3.4 was recorded about 23 minutes before the main jolt. It was centered a few miles to the southeast near Trinidad Reservoir.

Two quakes measuring M3.4 and M3.5 were recorded slightly to the south last week on August 28, 2001. These were the first tremors detected in the area since a trio of M3s struck in 1996.

The last quake to register in the M4 range occurred in 1973 and the largest quake measured M4.6 and happened in 1966. A "good jolt" happened in 1878, same year as the Charleston, S.C. M7.8 earthquake, that was sharply felt but there is no mention of the estimated magnitude.

See a list of southern Colorado earthquakes near Trinidad.

Felt reports
The main M4.0 shock was widely felt in Picketwire Valley from Trinidad, Secundo and Valdez. Many people reported a "rippling" of floors and walls, jiggling of windows and a few light items toppling from tables or shelves. A few pictures also fell from walls. There was no word of items breaking. The M3.4 aforeshock was also felt.

Additional notes
The Trinidad earthquake series continued on the next day.

Additional seismic information links:

• Seismo-Watch Links to Colorado Activity
• NEIC Earthquake Report Page.

Seismograms of the earthquake series from nearby stations:

• There are no nearby seismograph stations in the region.

Mainstream media news reports:

• Earth-shaking tremors felt in Trinidad, The Pueblo Chieftain Online, Wednesday September 05, 2001
• Also read about another recent Colorado earthquake below:
  • Colorado quakes nothing like California’s - Vail Daily News, September 2, 2001