Data for Quaternary faults in western Montana

The "World Map of Major Active Faults" Task Group is compiling published fault data, developing a digital
database of the fault data, and preparing a series of maps for the United States and other countries in the western
Hemisphere. The data is intended to portray the locations, ages, and activity rates of major earthquake-related
features such as faults, folds, and liquefaction features that have geologic evidence of Quaternary (1.6 Ma)
deformation. The Western Hemisphere effort is sponsored by International Lithosphere Program (ILP) Task Group
II-2; the data compilation, database, and map for the United States is funded largely by the National Earthquake
Hazard Reduction Program (NEHRP) through the U.S. Geological Survey. The ILP effort in the Western
Hemisphere is coordinated by Michael N. Machette, the digital database is designed and managed Kathleen M.
Haller, and map data are digitized and manipulated by Richard L. Dart. In addition to meeting the goals of the Task
Group II-2, this effort represents a key contribution to the new Global Seismic Hazards Assessment Program (ILP
Task Group II-0) for the International Decade for Natural Disaster Reduction.
This compilation, which documents the published data on Quaternary surface faulting in western Montana, is one of
many similar state or regional compilations that are planned for the project. Compilations for Arizona (Pearthree,
1998 #2945), Colorado (Widmann and others, 1998 #3441), New Mexico (Machette and others, 1998), and West
Texas (Collins and others, 1996 #993) are currently available and the compilation for features east of the Rocky
Mountain front will be available in early 2000 (Crone and Wheeler, in press). All are primarily a catalog of data that
includes a variety of geographic, geologic, and paleoseismologic parameters for known or assumed Quaternary
faults. These data compilations, the digital database, and the companion maps summarize the published information
on known tectonic features and present the information in an internally consistent format. The compilations will be
available in digital database format on the WorldWide Web in the near future, which will greatly improve their
utility. Release of data for individual states and regions within the United States in this text-based format was
necessary because of the time required to develop the national database.