This report is an updated and revised version of CGS Bulletin B-46, which was published in 1985. Earthquake data for 1986-1996, additional references and two sections have been added to the original publication. See the online ON-006-15M Colorado Earthquake and Fault Map, also. 152 pages, 3 tables. 66 figures. 1 plate. Digital PDF download. B-52D
Excerpts from the abstract:
This report contains data on about 500 earthquakes that have been felt or instrumentally located in Colorado since 1867. Information on the date, location, time, magnitude, depth, intensity, felt effects, and pertinent references for these earthquakes is included in this report. An isoseismal or intensity map is available for most of the larger events.
Observations and interpretations based on these maps and the historic seismicity are presented regarding seismicity patterns. A map illustrating the maximum experienced intensity in Colorado since 1867 was prepared by combining the known effects of all historical earthquakes. A series of graphs relating magnitude to felt area size and maximum intensity for the larger Rocky Mountain region earthquakes through 1996 are presented. Also included are equations that relate the size of the felt area to the magnitude of these earthquakes. Detection thresholds have lowered and seismicity has been more accurately located in parts of Colorado subsequent to release of our original Bulletin 46.