Quaternary Fault Data and map for Arizona

This report is a compilation of available data on Quaternary faults in Arizona as of the summer of 1998. These data were compiled as part of a effort to compile data and map information on Quaternary faults throughout the world, which is being overseen by Michael Machette of the U.S. Geological Survey. Michael Machette, Richard Dart, and Kathleen Haller provided substantial technical assistance in the preparation of these data, and the fault data forms were reviewed and edited by Michael Machette. As part of this effort, fault traces were entered into a Geographic Information System (GIS) database by the USGS. Map traces were plotted on 1:250,000-scale topographic base maps, and were digitized by Richard Dart and Lee-Ann Bradley of the USGS. They generated the 1:750,000-scale fault map that accompanies this database. neotectonic structures in Arizona. The first and most comprehensive of these is the state-wide compilation of neotectonic faults by Menges and Pearthree (1983), which was done primarily by Chris Menges. I also utilized the later state-wide compilation of young faults by Euge and others (1992). Regional compilations of the Douglas and Silver City 1:250,000-scale quadrangles in southeastern Arizona by Machette and others (1986) and the Flagstaff area by Pearthree and others (1996) provided most of the data for these areas. I also utilized indexes of geologic mapping in Arizona (Scarborough and Coney, 1982; Harris and others, 1994) and the geologic bibliography for the state (Trapp, 1996) developed by the Arizona Geological Survey. The data structure is set up to provide systematic information on each fault zone. Each fault has been assigned a number as part of the world-wide fault data set; faults are identified by number on the accompanying map. Fault names are based on published maps or reports. In cases where different names have been used for the fault, the alternative names are listed within the database. All of the faults are listed by name and number in the table on the following page. This table indicates where the data summary for each fault can be found, as well as the age of youngest activity and fault slip rate category. The individual fault data sheets include information on map and data sources, fault location, geologic setting of the fault, the geomorphic expression of the fault, recency of fault movement, fault slip rate(s), and fault zone length and orientation. Fault locations are rated good if they were originally mapped at 1:62,500 scale or larger, moderate if they were mapped at 1:130,000 scale or larger, or poor if there is substantial uncertainty in their location because of weak surface expression. Faults were grouped into slip rate categories of <0.02 mm/yr, < 0.2 mm/yr, and <1 mm/yr. Reported lengths are for the whole fault zone, not cumulative length of each individual fault in the zone, and orientations are averages for the fault zone. A composite list of references is at the end of this report. These fault data can be readily updated. Any feedback or any further data regarding individual faults is welcome, and more faults can be added as they are identified. (122 pages)