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Alebachew, Mengesha1, Allison Kennedy Thurmond1, Mohamed G. Abdelsalam1
(1) The University of Texas at Dallas, Richardson, TX

ABSTRACT: Optical-Radar-DEM Data Integration for Mapping Morphologically-Defined Structures in Extensional Tectonic Regions: Examples from the Afar Depression, Ethiopia

Integration of remote sensing data of different spatial and/or spectral characteristics and digital elevation models (DEM) can be extremely effective in mapping morphologically-defined structures in extensional tectonic regimes. Optical (Landsat Enhanced Thematic Mapper Plus (ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)), radar (RADARSAT) images, and DEMs extracted from the Global Topography 30-arc second dataset (GTOPO 30), Shuttle Radar Topography Mission (SRTM) and ASTER data are integrated to map structures in the Dobi Graben in the Afar Depression, Ethiopia. The NW-propagating Asal-Manda Inakir and the SE- propagating Manda Harare-Gobaat rifts bound the Dobe Graben in the NE and SW, respectively. Synthetic and antithetic high-angle normal faults and dilatational fractures characterize the NW-trending boundary faults. Lateral imbrication associated with gravitational collapse and concomitant sliding of individual blocks characterize the SW part of the Dobi Graben. Landsat ETM+ and RADARSAT data are fused using Color Normalization Transformation (CNT) to generate complimentary images from the optical multi-spectral data (which measure material composition) with the radar data (which emphasize surface roughness and morphology). The fused images are draped over GTOPO 30, SRTM and ASTER DEMs to create three-dimensional (3D) perspective views that are used to analyze the 3D geometry of geological features. Remote Sensing analysis combined with field studies allowed us to map the Dobe Graben in better details and to identify NW-trending high-angle normal and strike-slip faults, extensional imbrication fans. Remote sensing data integration can be used for aiding mapping structures in other tectonic extensional regimes.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004