Preliminary volcano-hazard assessment for Fisher volcano, Unimak Island, Alaska

Title:

Abstract:

Fisher volcano, containing the largest Holocene caldera in the Aleutian volcanic arc, is an active volcano near the center of Unimak Island, about 120 kilometers southwest of Cold Bay and about 175 kilometers northeast of Dutch Harbor. The volcano is composed of numerous small volcanic centers around and within a large, oval caldera 12 by 18 kilometers in diameter and 500 to 1,000 meters deep that formed during a catastrophic eruption about 9,400 years ago. Since then, more than 30 separate vents inside and outside the caldera have erupted; the most recent eruption occurred in 1826. These eruptions have produced lava flows and widespread tephra (volcanic ash) deposits, and have occasionally been accompanied by large floods and lahars. The history of Fisher volcano includes repeated explosive and non-explosive eruptions of varying levels of intensity, and indicates that this pattern will continue in the future. Understanding the variety of potential hazards associated with different types of volcanic processes typical of Fisher volcano can help minimize the adverse effect of future eruptions on humans and infrastructure. This report is part of a series of volcano hazard assessments being prepared by the Alaska Volcano Observatory. The reports are intended to describe the nature of volcanic hazards at Alaska volcanoes and show the extent of hazardous areas with maps, photographs, and other appropriate illustrations. The reports are preliminary and subject to revision as new data become available.

Supplemental_Information:

The DGGS metadata standard extends the FGDC standard to include elements that are required to facilitate our internal data management. These elements, referred to as "layers" group and describe files that have intrinsic logical or topological relationships and correspond to subdirectories within the data distribution package. The metadata layer provides an FGDC metadata file and may include other documentation files. Attribute information for each data layer is described in this metadata file under the "Entity_and_Attribute_Information" section. Data layer contents:

border:    A polygon shapefile that provides a generalized outline of the geographic area described by this report.
caldera-rim:    outline of the caldera rim
rim-buffer-10km-40km:    A shapefile outline of the caldera rim, 10km buffer, and a 40km buffer.
unimak-island-image:    Unimak Island shaded relief image, GeoTIF format

Value	Definition
0	caldera rim
10	Area likely to be affected by pyroclastic flows and surges during small- to moderate-sized eruptions, and maximum likely runout of large debris avalanches.
40	Maximum extent of pyroclastic flows that could occur during a large eruption similar to caldera-forming events that occurred ~9,400 years ago

Value

Definition

caldera rim

Area likely to be affected by pyroclastic flows and surges during small- to moderate-sized eruptions, and maximum likely runout of large debris avalanches.

Maximum extent of pyroclastic flows that could occur during a large eruption similar to caldera-forming events that occurred ~9,400 years ago

Data format:	Shapefiles, GeoTIFF raster file
Network links:	<http://dx.doi.org/10.14509/29146>

Data format:

Shapefiles, GeoTIFF raster file

Network links:

<http://dx.doi.org/10.14509/29146>

Preliminary volcano-hazard assessment for Fisher volcano, Unimak Island, Alaska

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