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Extraordinary sediment delivery and rapid geomorphic response following the 2008–2009 eruption of Chaitén Volcano, Chile

Water Resources Research

By:
ORCID iD , , ORCID iD , , , , and
https://doi.org/10.1002/2015WR018250

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Abstract

The 10 day explosive phase of the 2008–2009 eruption of Chaitén volcano, Chile, draped adjacent watersheds with a few cm to >1 m of tephra. Subsequent lava-dome collapses generated pyroclastic flows that delivered additional sediment. During the waning phase of explosive activity, modest rainfall triggered an extraordinary sediment flush which swiftly aggraded multiple channels by many meters. Ten kilometer from the volcano, Chaitén River channel aggraded 7 m and the river avulsed through a coastal town. That aggradation and delta growth below the abandoned and avulsed channels allow estimates of postdisturbance traction-load transport rate. On the basis of preeruption bathymetry and remotely sensed measurements of delta-surface growth, we derived a time series of delta volume. The initial flush from 11 to 14 May 2008 deposited 0.5–1.5 × 106 m3 of sediment at the mouth of Chaitén River. By 26 May, after channel avulsion, a second delta amassed about 2 × 106 m3 of sediment; by late 2011 it amassed about 11 × 106 m3. Accumulated sediment consists of low-density vesicular pumice and lithic rhyolite sand. Rates of channel aggradation and delta growth, channel width, and an assumed deposit bulk density of 1100–1500 kg m−3 indicate mean traction-load transport rate just before and shortly after avulsion (∼14–15 May) was very high, possibly as great as several tens of kg s−1 m−1. From October 2008 to December 2011, mean traction-load transport rate declined from about 7 to 0.4 kg−1 m−1. Despite extraordinary sediment delivery, disturbed channels recovered rapidly (a few years).

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Extraordinary sediment delivery and rapid geomorphic response following the 2008–2009 eruption of Chaitén Volcano, Chile
Series title:
Water Resources Research
DOI:
10.1002/2015WR018250
Volume:
52
Issue:
7
Year Published:
2016
Language:
English
Publisher:
American Geophysical Union
Publisher location:
Washington, D.C.
Contributing office(s):
Volcano Science Center
Description:
20 p.
First page:
5075
Last page:
5094
Country:
Chile
Other Geospatial:
Chaitén Volcano
Online Only (Y/N):
N
Additional Online Files (Y/N):
N