SPECTRAL CHARACTERISTICS OF LANDSLIDES AND DEBRIS FLOWS USING LANDSAT 7 SCENES, WASATCH FRONT, UTAH

The improved resolution of Landsat - 7 over its predecessor Landsat - 5 provides an opportunity to re-examine the feasibility of using Landsat scenes to determine unique spectral characteristics of landslides and debris flows. This problem has been previously examined but advancement was hampered by lower computer capability and poor radiometric resolution. Using four Landsat - 7 scenes from three different dates and covering the majority of the Wasatch Front, this study examines recent landslides and debris flows (and surrounding areas) to determine if these events share unique characteristics. These characteristics could be extrapolated to other regions and establish areas that are likely to experience mass movement in the future. Particular attention is paid to Band 6 since it is responsive to soil moisture, an increase in which could be a factor in initiation of mass movement events. The Wasatch Front serves as a first-rate laboratory for study because of its many recent and historic landslides and debris flows.

The ArcView 3.2 Image Analysis extension was used for this study. This extension is accessible to users who may be familiar with the ArcView environment but less familiar with image processing software. Nearly all of this extension's capabilities were used to study the four scenes, including supervised and unsupervised classification, utilizing various band combinations and vegetative indexes. For supervised classification, recently active debris flows or landslides were used as training sites, with those characteristics applied to the entirety of the scene. Ideally, this procedure identifies other regions that have the same characteristics and could become active.