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GeoHazard | GeoResource

Documenting Liquefaction Failures Using Satellite Remote Sensing

Earthquake induced liquefaction is a major cause of structural and lifeline damages around the world. Documenting these instances of liquefaction is extremely important to help earthquake professionals to better evaluate design procedures, and enhance their understanding of liquefaction processes. Currently, after an earthquake event, field-based mapping of liquefaction remains sporadic due to inaccessibility, and difficulties in identifying and mapping large aerial extents. Researchers have used change detection using remotely sensed pre- and post-event satellite images to assist field reconnaissance. However, general change detection is only a first step in developing effective field reconnaissance strategies for liquefaction due to the inherent assumption of the approach that all the change observed within the two dates are induced by the liquefaction. We hypothesize that as liquefaction occurs in saturated granular soils due to an increase in pore pressure, the liquefaction related terrain changes should have an associated increase in soil moisture with respect to the surrounding non-liquefied regions. Mapping the increase in soil moisture using pre- and post-event images that are sensitive to soil moisture is suitable for identifying areas that have undergone liquefaction. We verify this by change detection of pre and post- event Landsat ETM+ tasseled cap wetness images. The results indicate that satellite remote sensing can be an integral part in regionally documenting liquefaction failures.

Documenting Liquefaction

Change detection showing increased wetness asociated with liquefaction derived by principal component analysis of pre- and post-event Landsat ETM+ tasseled cap wetness images (Jan 2001 & Feb 2001)