Earthquake ID:  210 Date: 01/23/1966
Intensity:  VII
Time: 1:56 AM
Magnitude:  5.5
Earthquake Depth: 3  (kM)
Magnitude USGS:  5.5
Latitude: 37
Magnitude Other:  5.1 HDP-2 Longitude: -107
Earthquake Information:
The Colorado-New Mexico border region was rocked by a moderate earthquake on January 23, 1966 that centered near Dulce, New Mexico. Felt effects and intensities for the earthquake were described by von Hake and Cloud (1968) and intensities for the USCGS quarterly series “Abstracts of Earthquake Reports”. Figure 31 is an isoseismal map of the event prepared from the available felt reports. It indicates the quake was felt over a rectangular-shaped region covering about 27,000 km 2. Von Hake and Cloud (1968) reported a felt area of 39,000 km 2 for this event. Between January 22 and January 28 (local time) the USCGS seismological center in Albuquerque recorded 119 events in the Dulce area. Three temporary seismographs were installed in the Dulce area on January 28th. During the first week of operation 218 earthquakes were recorded, all located in a small area near Dulce. 532 aftershocks were recorded during 30 days of monitoring, with hypocentral depths of about 5 to 10 km (Hoffman and Northrop, 1977). Earthquake activity continued at a high rate for about a year following the main shock. Minor activity continues to be instrumentally detected in the Dulce area. There are discrepancies in the epicentral locations for many of the aftershocks following the Dulce earthquake in the various catalogs. We have attempted to include in Table 1 all events that occurred within Colorado or on the border with New Mexico. Nearly every house in Dulce was damaged to some degree by the earthquake, but the princi-pal damage was to structures at the Bureau of Indian Affairs (BIA) complex and local schools. Damage was estimated at $200,000, but no deaths or injuries were reported. The BIA dormitories suffered extensive damage to interior and exterior walls. The steam-heating plant for the BIA school was severely damaged. Older homes in the Dulce area experienced considerable structural damage, but new homes suffered mostly only cosmetic damage. A number of chimneys were damaged, especially those 0.3 to 0.7 meters high. Considerable rockfall occurred on buttes in the area. Photographs of some of the damage are contained in von Hake and Cloud (1968). A maximum intensity of VII was originally reported for this quake in Dulce, but Hoffman and Northrup (1977) suggest a VII to VIII or VII+ rating may be more appropriate. Intensity VI damage was reported in several locations along the Colorado-New Mexico border. Earthquake magnitude was originally determined at mb 5.5. Later studies by Herrmann and others (1980) reported a magnitude of mbLg 5.1 magnitude for the main shock.
Location Map: (click on image for full size view)
Location Map for Earthquake ID 210
47 - Herrmann, R.B., Dewey, J.W., and Park, S.K., 1980, The Dulce, New Mexico earthquake of 23 January 1966: Seismological Society of America Bulletin, v. 70, no. 6, p. 2171-2183.
50 - Hoffman, J.P., and Northrop, S.A., 1978, The Dulce, New Mexico, earthquake January 23, 1966: Earthquake Notes, v. 48, p. 3-20.
74 - National Oceanic and Atmospheric Administration, 1985, Earthquake intensity file for Colorado-computer printout: National Oceanic and Atmospheric Administration, Environmental Data Services, Boulder, Colorado.
123 - U.S. Geological Survey, 2008, Computer-file printouts of Colorado earthquakes, 1981-present: prepared by U.S. Geological Survey, National Earthquake Information Center, July 17, 1985, January 12, 1996, February 21, 1997, January 6, 2003, and April 15, 2004. Web-based searches from USGS NEIC website, 2004-present.
130 - von Hake, C.A., and Cloud, W.K., 1968, United States earthquakes 1966: U.S. Coast and Geodetic Survey, 110 p.