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| Titel |
Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico) |
| VerfasserIn |
D. Schneider, H. Delgado Granados, C. Huggel, A. Kääb |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 3 ; Nr. 8, no. 3 (2008-06-17), S.559-571 |
| Datensatznummer |
250005533
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| Publikation (Nr.) |
 copernicus.org/nhess-8-559-2008.pdf |
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| Zusammenfassung |
| Lahars frequently affect the slopes of ice-capped volcanoes. They can be
triggered by volcano-ice interactions during eruptions but also by processes
such as intense precipitation or by outbursts of glacial water bodies not
directly related to eruptive activity. We use remote sensing, GIS and lahar
models in combination with ground observations for an initial lahar hazard
assessment on Iztaccíhuatl volcano (5230 m a.s.l.), considering also
possible future developments of the glaciers on the volcano. Observations of
the glacial extent are important for estimations of future hazard scenarios,
especially in a rapidly changing tropical glacial environment. In this
study, analysis of the glaciers on Iztaccíhuatl shows a dramatic
retreat during the last 150 years: the glaciated area in 2007 corresponds to
only 4% of the one in 1850 AD and the glaciers are expected to survive
no later than the year 2020. Most of the glacial retreat is considered to be
related to climate change but in-situ observations suggest also that geo-
and hydrothermal heat flow at the summit-crater area can not be ruled out,
as emphasized by fumarolic activity documented in a former study. However,
development of crater lakes and englacial water reservoirs are supposed to
be a more realistic scenario for lahar generation than sudden ice melting by
rigorous volcano-ice interaction. Model calculations show that possible
outburst floods have to be larger than ~5×105 m3 or
to achieve an H/L ratio (Height/runout Length) of 0.2 and lower in order to
reach the populated lower flanks. This threshold volume equals 2.4%
melted ice of Iztaccíhuatl's total ice volume in 2007, assuming 40%
water and 60% volumetric debris content of a potential lahar. The model
sensitivity analysis reveals important effects of the generic type of the
Digital Terrain Model (DTM) used on the results. As a consequence, the
predicted affected areas can vary significantly. For such hazard zonation,
we therefore suggest the use of different types of DTMs and flow models,
followed by a careful comparison and interpretation of the results. |
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