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<br />002797 <br /> <br />Methods of Landslide Evaluation <br /> <br />The predecessor to landslide mitigation is the recognition of the presence or <br />the potential for development of slope movement and the type and causes of the <br />movement. Recognition depends on an accurate evaluation of the geology, <br />landforms, and interrelated factors such as environmental conditons and human <br />act ivit ies. <br /> <br />Techniques for recognizing the presence or potential development of landslides <br />include: <br /> <br />o <br /> <br />map analysis <br />analysis of aerial photography <br />preliminary field reconnaissance <br />geophysical studies <br />drill ing <br />computerized landslide terrain analysis <br /> <br />o <br /> <br />o <br /> <br />o <br /> <br />o <br /> <br />o <br /> <br />Map Analysis <br /> <br />The analysis of various types of maps is usually one of the first steps in a <br />landsl ide investigation. Maps used include: geologic, topographic, soils, <br />and terrain. A general idea of landslide susceptibility can be derived from <br />these maps, based on a knowledge of the geologic materials. <br /> <br />Aerial Photography <br /> <br />Aerial photogrpahy is one of the most valuable techniques since it provides a <br />three-dimensional overview of the terrain and indicates human activities as <br />well as much geologic information. In addition, the availability of many <br />types of aerial imagery, such as satellite, infrared, radar, etc., make this a <br />very flexible and versatile technique. <br /> <br />Field Reconnaissance <br /> <br />Many of the more subtle evidences of slope movement cannot be identified on <br />maps and photographs. Also, if an area is heavily forested or has been <br /> <br />- 11 - <br />