HR: 1340h
AN: V23A-0616    [Abstracts]
TI: Tephra Studies by the Alaska Volcano Observatory: Present and Future Research
AU: * Waythomas, C F
EM: chris@usgs.gov
AF: U.S. Geological Survey, Alaska Science Center, Alaska Volcano Observatory, 4230 University Drive Suite 201, Anchorage, AK 99508 United States
AU: Wallace, K L
EM: klwallace@usgs.gov
AF: U.S. Geological Survey, Alaska Science Center, Alaska Volcano Observatory, 4230 University Drive Suite 201, Anchorage, AK 99508 United States
AB: Tephra from Aleutian arc volcanoes constitutes an important volcanic hazard for Alaska, western Canada, and some parts of the conterminous U.S. where even small amounts of airborne ash may have dire consequences for jet aircraft traversing North Pacific and western U.S. air routes. Motivated by the need to address volcanic ash hazards on a regional scale, we have initiated a program of tephra studies within the auspices of the Alaska Volcano Observatory (AVO) of the U.S. Geological Survey. A concentrated focus on tephra problems and a new laboratory facility within AVO will help facilitate studies of Quaternary age tephra at Alaskan volcanoes by providing a regional center for laboratory analyses of volcanic ash and standardized web-based reporting and archiving of tephra data. In its first year of operation, the laboratory has been engaged in research at Veniaminof, Mt. Spurr, and Augustine volcanoes, has sponsored research on Holocene tephra deposits of upper Cook Inlet, and has initiated analytical studies of tephra deposits on Adak and Kanaga Islands in the western Aleutians. The objective of these studies is to develop multiparameter techniques for characterization and correlation of tephra deposits, establish radiocarbon-controlled tephrostratigraphic frameworks, and to evaluate the magnitude and frequency of tephra-producing eruptions. In the upper Cook Inlet region of Alaska, we and our colleagues have begun developing a comprehensive record of ash fall by systematically selecting and coring shallow lakes and evaluating the tephra preserved in the lacustrine sediment. Sediment cores from these lakes contain numerous tephra deposits of Holocene age in datable context that can be correlated with proximal tephra deposits on the flanks of their source volcanoes. By combining tephra data from lacustrine deposits and natural exposures we hope to develop a robust geologic catalog of tephra deposits that will enable long-distance correlation of tephras, provide greater detail on the chronology of eruptions, and establish a longer-term context for tephra hazards. Future work will be focused on improving correlation of tephras, identification of source volcanoes, developing reference datasets, and developing a web-served database of tephra data.
DE: 8404 Ash deposits
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting