Historic Earthquakes

Near Dulce, New Mexico
1966 01 23 01:56:38.1 UTC (local 01/22)
Magnitude 5.1
Intensity VII

This earthquake affected to some extent almost every house in Dulce and damaged chimneys throughout the area. Property damage was estimated at about $200,000. The earthquake was caused by normal faulting on a fault striking approximately north-northwest, that probably had its maximum activity in Miocene time. Distribution of aftershock epicenters suggests that the main shock triggered aftershock activity on adjacent faults. The aftershock activity continued in the area for a year.

Property damage was most severe at the Dulce Bureau of Indian Affairs School and dormitory complex and the Dulce independent schools. Much plaster fell from ceilings in the dormitories, and several brick walls sustained vertical fractures that extended from ground to roof. Brick walls in the steam-heating plant were displaced from vertical alignment as much as 3 centimeters, and two boilers (each weighing 10 tons) were displaced about 0.6 centimeters at their bases. Also, an 18-meter-high smokestack buckled, and only guy wires prevented it from falling.

Huge masses of shale and sandstone fell down the slopes from nearby Dulce Point. In addition, several small cracks formed in fill across the frozen roads in the Dulce area, but there was no evidence of ground displacement or fissuring. Also felt in southern Colorado.

Abridged from Seismicity of the United States, 1568-1989 (Revised), by Carl W. Stover and Jerry L. Coffman, U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993.