Derivation of Digital Elevation Models of Volcanoes using ASTER

Abstract

We are creating digital elevation models (DEMs) of volcanoes usingdata obtained by the ASTER instrument on the Terra spacecraft. Nearinfrared data from ASTER can be used to produce DEMs via photogrammetrictechniques by virtue of the nadir and aft-looking cameras (providinga fixed base-to-height ratio of 0.6). An automated stereo image auto-correlationtechnique is used to produce DEMs. To date, we have generated DEMsfor Socompa volcano (Chile) and the Koolau/Waianae volcanoes on Oahu(Hawaii). As part of a data validation effort, these topographicdata sets are being compared with existing elevation data collectedby repeat-pass radar interferometry using ERS-2, and the TOPSAR airborneinterferometric radar, respectively. ASTER DEMs appear to be a valuablenew data source for volcanological research; Socompa, for instance,experienced a catastrophic landslide several thousand years ago,and we are using the DEM to study the flow characteristics of thelandslide. ASTER DEMs appear to be highly complementary to othertypes of satellite-derived data, such as Shuttle Radar TopographyMission (SRTM) and repeat-pass radar interferometry. ASTER data haveseveral advantages, including low cost (data are free), high spatialresolution (15 m vs. 30 m for ERS-2, or 90 m global coverage forSRTM), good correlation over vegetated areas and high-relief terrain,and the ability to obtain repeat coverage (unlike SRTM). Disadvantagesinclude the potential masking by clouds, low correlation in areasof low relief, and potential low correlation due to atmospheric hazewhen the instrument is operated in cross-track mode. One of the goalsin our work is to better understand potential and limitations ofthe ASTER DEMs for geomorphic studies of volcanoes.