Imaging the Morphotectonic Setting of Seismic Events and Their Propagation Paths: Methodology and Comparative Studies.
Abstract
Geomorphic interpretation of geologic features using DEMs (Digital Elevation Models) and satellite imagery can yield useful information on long- term fault activity in the absence of detailed ground mapping. Mapping of probable active faults in Central Asia and estimation of the type of offset from DEMs is combined with digitizations of published fault maps, Landsat TM and SPOT imagery, and earthquake catalogs in a Geographic Information System to provide information on the probability that a shallow seismic event is a natural earthquake, thus aiding in the verification of nuclear test ban treaties. Topographic characteristics are analyzed at resolutions from 100 m to 50 km. Several studies have noted the lack of propagation of high-frequency Lg waves across major mountain ranges, such as the Himalaya-Pamirs and Sierra Nevada. Extreme surface roughness caused by fluvial and glacial erosion may significantly contribute to explaining the lack of propagation across high mountain ranges. Use of Lg amplitudes along such paths for discrimination or yield estimation could be invalid or require correction factors. Profiles of topography in a swath along the propagation path of Lg from a given event show the amount of topographic relief at the surface that could contribute to scattering high-frequency energy.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 20, 1991
- Accession Number
- ADA239733
Entities
People
- Bryan L. Isacks
- Eric J. Fielding
- Muawia Barazangi
- Richard W. Allmendinger
Organizations
- Cornell University