HR: 0830h
AN: G31B-0711    [PDF]
TI: Quaternary Fault Database for the Basin and Range Province of Nevada and Utah: Fodder for PBO's Gristmill
AU: * Machette, M N
EM: machette@usgs.gov
AF: U.S. Geological Survey, MS 966, Box 25046, Denver, Co 80225-0046 United States
AU: Haller, K M
EM: haller@usgs.gov
AF: U.S. Geological Survey, MS 966, Box 25046, Denver, Co 80225-0046 United States
AU: Dart, R L
EM: dart@usgs.gov
AF: U.S. Geological Survey, MS 966, Box 25046, Denver, Co 80225-0046 United States
AB: The USGS has nearly completed a comprehensive compilation of Quaternary faults and folds that could be potential seismic sources for large surface-rupturing earthquakes throughout the U.S. The compilation consists of GIS-based maps of Quaternary faults and folds and a robust (i.e., $>$7,500 p.) database that will be accessible via the Internet. The data for the Basin and Range (B\&R) province will prove very useful for comparing Quaternary geologic deformation rates with GPS-derived geodetic strain rates (i.e., Earthscope/PBO). This poster focuses on the B\&R province of Nevada and Utah and features a new map of Quaternary faults and folds, as well as GPS stations (USGS and Cal Tech) and paleoseismic study sites. Current campaign-style and continuous GPS stations are well distributed across the northern B\&R, whereas paleoseismic studies have been concentrated mainly along the Intermountain and Central Nevada Seismic belts and the Yucca Mountain area. The Quaternary fault and fold map shows the time of most recent fault (or fold) movement, sense of movement, slip (or uplift) rate category, and a numeric identifier. GIS data are maintained in ArcInfo on a Unix server and linked to a File Maker Pro web database that contains comprehensive written descriptions, several of which are displayed on this poster. More than 1,000 Quaternary faults are shown on the map, the majority of which are within the highly extended B\&R terrain of Nevada and western Utah. To visually depict potential earthquake sources, we categorized the time of most recent movement (surface rupture) on the faults as $<$1.6 Ma, (black), $<$750 ka (blue), $<$130 ka (green), $<$15 ka (orange), and historic ($<$200 yrs, red). The $<$130,000 year time frame is probably the most relevant for seismic-hazards assessments because it encompass multiple earthquake cycles on most B\&R faults. The slip-rate categories (in mm/yr) are binned to separate relatively inactive faults ($<$0.2, thin lines) from active normal faults (0.2-1, medium lines) and moderately (0.2-1) to quite active ($>$1 thick lines) oblique- and strike-slip faults. With few exceptions, the only faults that exceed $>$2 mm/yr are the Holocene strike- or oblique-slip faults in the western B\&R province.
DE: 7221 Paleoseismology
DE: 7230 Seismicity and seismotectonics
DE: 8100 TECTONOPHYSICS
SC: Geodesy [G]
MN: 2003 Fall Meeting