HR: 1340h
AN: S43A-1050    [Abstracts]
TI: Preliminary Use of the Seismo-Lineament Analysis Method (SLAM) to Investigate Seismogenic Faulting in the Grand Canyon Area, Northern Arizona
AU: * Cronin, V S
EM: Vince_Cronin@baylor.edu
AF: Geology Department, Baylor University One Bear Place #97354, Waco, TX 76798-7354, United States
AU: Cleveland, D M
EM: David_Cleveland@baylor.edu
AF: Geology Department, Baylor University One Bear Place #97354, Waco, TX 76798-7354, United States
AU: Prochnow, S J
EM: Shane_J_Prochnow@baylor.edu
AF: Geology Department, Baylor University One Bear Place #97354, Waco, TX 76798-7354, United States
AB: This is a progress report on our application of the Seismo-Lineament Analysis Method (SLAM) to the eastern Grand Canyon area of northern Arizona. SLAM is a new integrated method for identifying potentially seismogenic faults using earthquake focal-mechanism solutions, geomorphic analysis and field work. There are two nodal planes associated with any double-couple focal-mechanism solution, one of which is thought to coincide with the fault that produced the earthquake; the slip vector is normal to the other (auxiliary) plane. When no uncertainty in the orientation of the fault-plane solution is reported, we use the reported vertical and horizontal uncertainties in the focal location to define a tabular uncertainty volume whose orientation coincides with that of the fault-plane solution. The intersection of the uncertainty volume and the ground surface (represented by the DEM) is termed a seismo-lineament. An image of the DEM surface is illuminated perpendicular to the strike of the seismo- lineament to accentuate geomorphic features within the seismo-lineament that may be related to seismogenic faulting. This evaluation of structural geomorphology is repeated for several different azimuths and elevations of illumination. A map is compiled that includes possible geomorphic indicators of faulting as well as previously mapped faults within each seismo-lineament, constituting a set of hypotheses for the possible location of seismogenic fault segments that must be evaluated through fieldwork. A fault observed in the field that is located within a seismo-lineament, and that has an orientation and slip characteristics that are statistically compatible with the fault-plane solution, is considered potentially seismogenic. We compiled a digital elevation model (DEM) of the Grand Canyon area from published data sets. We used earthquake focal-mechanism solutions produced by David Brumbaugh (2005, BSSA, v. 95, p. 1561-1566) for five M > 3.5 events reported between 1989 and 1995. Fieldwork to test our hypotheses is planned for the spring of 2008. Based on a preliminary analysis, the northwest-trending Muav, Tipoff, Cremation and Phantom Faults are all located within northwest-trending seismo-lineaments associated with recorded earthquakes that are characterized by normal (slightly oblique) focal mechanism solutions. This is consistent with Brumbaugh's suggestion that present-day seismicity in the eastern Grand Canyon is concentrated on faults with a northwest trend.
DE: 7215 Earthquake source observations (1240)
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8002 Continental neotectonics (8107)
DE: 8010 Fractures and faults
SC: Seismology [S]
MN: 2007 Fall Meeting