Volcano collapse along the Aleutian Ridge (western Aleutian Arc)

C Montanaro,J Beget

doi:10.5194/nhess-11-715-2011

Abstract

Abstract. The Aleutian Ridge, in the western part of the Aleutian Arc, consists of a chain of volcanic islands perched atop the crest of a submarine ridge with most of the active Quaternary stratocones or caldera-like volcanoes being located on the northern margins of the Aleutian Islands. Integrated analysis of marine and terrestrial data resulted in the identification and characterization of 17 extensive submarine debris avalanche deposits from 11 volcanoes. Two morphological types of deposits are recognizable, elongate and lobate, with primary controls on the size and distribution of the volcanic debris being the volume and nature of material involved, proportion of fine grained material, depth of emplacement and the paleo-bathymetry. Volume calculations show the amount of material deposited in debris avalanches is as much as three times larger than the amount of material initially involved in the collapse, suggesting the incorporation of large amounts of submarine material during transport. The orientation of the collapse events is influenced by regional fault systems underling the volcanoes. The western Aleutian Arc has a significant tsunamigenic potential and communities within the Aleutian Islands and surrounding areas of the North Pacific as well as shipping and fishing fleets that cross the North Pacific may be at risk during future eruptions in this area.

Highlights

Island volcanoes sometimes undergo huge sector collapses generating submarine volcanic landslides and giant debris avalanches that can travel for tens of kilometers across the sea floor
The Aleutian Ridge, in the western part of the Aleutian Arc, consists of a chain of volcanic islands perched atop the crest of a submarine ridge with most of the active Quaternary stratocones or caldera-like volcanoes being located on the northern margins of the Aleutian Islands
The western Aleutian Arc has a significant tsunamigenic potential and communities within the Aleutian Islands and surrounding areas of the North Pacific as well as shipping and fishing fleets that cross the North Pacific may be at risk during future eruptions in this area

Summary

Introduction

Island volcanoes sometimes undergo huge sector collapses generating submarine volcanic landslides and giant debris avalanches that can travel for tens of kilometers across the sea floor. Similar deposits have been found around volcanic islands and island arcs above subduction zones, including volcanoes in the Lesser Antilles Arc (Boudon et al, 2007), Japanese Arc (Satake and Kato, 2001), Tonga-Kermadec Arc (Wright et al, 2006), Bismark Island (Silver et al, 2009), Aeolian Island (Tibaldi, 2001; Romagnoli et al, 2009) and the Aleutian Island Arc (Coombs et al, 2007b) The recurrence of such events today could generate huge tsunamis that would cause damage and destruction at coastal facilities and loss of life in coastal communities (Beget, 2000; Ward and Day, 2003). In these areas we can still identify DA deposits, but without new high resolution imagery we cannot determine whether more than one deposit is present

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