HR: 1330h
AN: OS22B-1162    [PDF]
TI: Relative Tsunami Hazard Maps, Humboldt County, California
AU: * Dengler, L A
EM: lad1@humboldt.edu
AF: Humboldt State University, #1 Harpst St, Arcata, CA 995521 United States
AU: Ludy, B R
EM: brl13@humboldt.edu
AF: Humboldt State University, #1 Harpst St, Arcata, CA 995521 United States
AU: Patton, J R
EM: jason@mcbaintrush.com
AF: Humboldt State University, #1 Harpst St, Arcata, CA 995521 United States
AB: We present a series of maps depicting the relative tsunami hazard of coastal Humboldt County in Northern California. Unlike inundation maps that show a single line to show the inland extent of flooding, these maps use a four-color zonation to represent relative risk. The highest hazard area has experienced tsunami or storm wave inundation in historic times. These areas include beaches and low coastal bluffs on the open coast and low areas adjacent to Humboldt Bay and major river deltas. The high hazard zones are also mapped as zone A (100 year flooding) or zone V (100 year flood with wave action) on FEMA Flood Insurance Rate Maps. Moderate hazard zones are areas likely to be flooded by a major tsunami generated by the Cascadia subduction zone based on published paleotsunami studies, numerical modeling (Bernard and others, 1994) and observations of recent tsunamis elsewhere. Current estimates of major Cascadia earthquake recurrence averages about 500 years. Low hazard zones show no evidence of flooding in the paleotsunami record and are likely to provide refuge in all but the most extreme event. No hazard areas are too high in elevation and/or too far inland to be at risk. A continuous gradational color scale ranging from red (high hazard) through orange (medium), yellow (low) to gray (no hazard) depicts the zones. The blurred boundaries help convey the continuum of possible events and the uncertainty in delineating distinct inundation lines. The maps are GIS based to facilitate ready adaptation by planners and emergency managers. The maps are intended for educational purposes, to improve awareness of tsunami hazards and to encourage emergency planning efforts of local and regional organizations by illustrating the range of possible tsunami events.
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting