Remotely measuring tectonically offset geomorphic features using light detection and ranging (LiDAR) data
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The increasing availability of airborne and terrestrial LiDAR datasets has facilitated an explosion of scientific studies that utilize high-resolution topographic data to study earth surface processes. Web-based repositories such as http://www.opentopography.org provide public access to LiDAR datasets for a myriad of purposes.
Of particular geologic interest are studies of active fault zones where LiDAR topographic data provides a means to remotely analyze sub-meter fault geomorphology. Geomorphic features (e.g., stream channels, alluvial bars) that cross a fault before a major earthquake can be measured after an earthquake to determine earthquake slip at a point. A series of these offset features along a fault trace can be used to determine the slip distribution of a surface-rupturing earthquake. Because these slip distributions are used for earthquake magnitude and hazard calculations, the accuracy and precision of these measurements is of utmost importance.
Measurement Validation Experiment
We devised this study to test the repeatability of LiDAR-based offset measurements made with different tools by users of varying skill levels. No prior experience necessary; instructions were provided on each page. We chose ten different offset features from major active faults in western North America; features varied in age from 2 to hundreds of years old and were of excellent to poor quality. Measurement methods spanned a range of complexity: paper image and scale (least complex), the Google Earth ruler tool, and a MATLAB GUI for calculating backslip required to properly restore tectonic deformation (most complex).
Questions and/or comments should be directed to Barrett Salisbury at firstname.lastname@example.org.
page last updated: 2014/01/19