Up-to-date, accurate topographic data are a crucial resource for volcanic research and risk mitigation efforts, in particular, for modeling
volcanic flow processes at a detailed spatial resolution. In this paper, we examine the utility of the Advanced Spaceborne Thermal Emission
and Reflection Radiometer (ASTER) instrument currently operating on the NASA Terra satellite, which provides near infrared (VNIR) stereo
imaging from which topography can be derived. We wrote software to generate digital elevation models (DEMs) from the ASTER level 1A
product, which employs an automated stereo matching technique to calculate the parallax offsets between the images acquired by the nadirand
aft-looking sensors. Comparison of ASTER DEMs with DEMs derived from other sources (digitized 1:50 K topographic maps and aerial
interferometric radar) at Ruapehu volcano reveal an RMS error of about 10 m for the ASTER DEM, in the absence of significant atmospheric
water vapor. A qualitative assessment of surface features showed that the ASTER DEM is superior to the interpolated 1:50 K map product
but falls short of the detail provided by aerial interferometric radar, especially in terms of stream channel preservation. A second ASTER
DEM was generated for Taranaki volcano, where previously only 1:50 K topographic map data were available. Although the 2000 Space
Shuttle radar topography mission (SRTM) will largely remedy the previous global paucity of adequate topographic data at volcanoes, such as
Taranaki, we anticipate the problem that at active volcanoes, the topography may change significantly following activity, rendering the
SRTM data inaccurate. With the high temporal coverage of the dataset, ASTER not only provides a means to update significant (>10 m)
topographic measurements at active volcanoes via a time-series of DEMs, but also provides a simultaneous means to map surface cover and
localized land-use via the near infrared sensors. Thus we demonstrate the potential for up-to-date volcanic economic risk assessment using
geographic information systems (GIS) analysis.
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