HR: 11:20h
AN: V42B-04    [Abstracts]
TI: Lahar Hazard Mapping of Mount Shasta, California: A GIS-based Delineation of Potential Inundation Zones in Mud and Whitney Creek Basins
AU: * McClung, S C
EM: steve@lifetime.oregonstate.edu
AF: Department of Geosciences, Oregon State University, 104 Wilkinson Hall Oregon State University, Corvallis, OR 97331
AU: Roberts, M
EM: mar22@axe.humboldt.edu
AF: SHN Engineers & Geologists, 812 Wabash Avenue, Eureka, CA 95501
AB: Mount Shasta, the southernmost stratovolcano in the Cascade Range (41.4°N) has frequently produced lahars of various magnitudes during the last 10,000 years. These include large flows of eruptive origin, reaching more than 40 km from the summit, and studies have shown that at least 70 debris flows of noneruptive origin have occurred during the last 1,000 years in various stream channels. The Mud and Whitney Creek drainages have historically produced more debris flows than any other glacier-headed channel on the volcano. Periods of accelerated glacial melt have produced lahars in Whitney Creek with a volume of 4 x 10⁶ m³ and a runout distance of about 27 km from the summit. Mud Creek flows from 1924 to 1931 covered an area of more than 6 km² near the community of McCloud with an estimated 23 x 10⁶ m³ of mud. A much older lahar in Big Canyon Creek may have deposited a volume of 70 x 10⁶ m³ over present day Mount Shasta City and beyond. The LAHARZ inundation modeling tool was used to objectively delineate lahar inundation zones in Whitney and Mud Creek basins based on a 30 m digital elevation model and a range of potential volumes extrapolated from local events. The predicted inundation areas for the largest volume modeled are between 31 and 34 km², reaching distances of about 32 km from the summit, well within reach of populated areas and significant bodies of water on the NW and SE flanks of the volcano. The resulting lahar inundation hazard zones are discussed with a focus on model limitations, cartographic implications, and the advantages of using 3D hazard maps.
UR: http://oregonstate.edu/~mcclungs/shasta/
DE: 0720 Glaciers
DE: 1821 Floods
DE: 1894 Instruments and techniques: modeling
DE: 8400 VOLCANOLOGY
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005