Date of Award:

2000

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geology

Advisor/Chair:

Darrell S. Kaufman

Abstract

This thesis describes the results of a study of 33 tephra layers found within two peat sections near Anchor Point and Homer, Alaska, on the lower Kenai Peninsula. Numerous lower Cook Inlet volcanoes have been active through the Holocene. Tephra layers found at these two sites provide a partial record of their eruptive activity. The hazards that accompany this activity have increased as populations and commercial activities expand and air traffic over the region increases. The tephras analyzed for this study provide an initial geochemical database for the lower Cook Inlet volcanoes. The database is available in electronic format at the U.S. Geological Survey, Alaska Volcano Observatory. The Anchor Point and Homer sections contain tephras from Augustine, Iliamna, and possibly other volcanoes in the region. Anchor Point, the principal section for this study, yielded ten 14C ages ranging from 645 ± 85 cal yr BP at a depth of 14 cm to 8810 ± 205 cal yr BP at 270 cm. Seventeen tephra layers from Anchor Point and 16 from Homer were characterized by stratigraphic position, age, and grain-discrete major-element geochemical analysis by electron microprobe. Nine tephra layers are correlated by geochemical analysis between the Anchor Point and Homer sections. Several newly discovered tephra layers have been correlated with source volcanoes, three with Augustine and at least seven with Iliamna Volcano. The average recurrence interval of tephra fall events at Anchor Point is approximately 520 yrs.

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Included in

Geology Commons

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