NEW HIGH-TECH NEW HIGH-TECH TOOLS FOR TOOLS FOR IDENTIFYING IDENTIFYING

LANDSLIDE FEATURESLANDSLIDE FEATURES

Part 14 Part 14

• Digital map image of the West Lost Trail Creek Landslide created by overlaying USGS DOQQ aerial photo on 10 m Digital Elevation Model, then rotating in space, using ArcGIS 9.1

Synthetic Aperture Synthetic Aperture Radar (SAR)Radar (SAR)

• SARSAR has ability to see through has ability to see through clouds and woody vegetation, clouds and woody vegetation, up to about 4 inches thick. up to about 4 inches thick.

• It provides It provides acute vertical acute vertical exaggeration of geomorphic exaggeration of geomorphic featuresfeatures, crucial to landslide , crucial to landslide hazard mappinghazard mapping

• Image resolution and density Image resolution and density controls scale of mappable controls scale of mappable features, such as these debris features, such as these debris lobes lobes

LiDARLiDARLight Detection and Light Detection and

RangingRanging

• LiDAR image of Paine Run, Virginia revealed an active fault scarp never previously seen, mapped, or even imagined!

• “Bare Earth” assessment has incredible potential for landslide mapping

Seattle/Toe Jam Hill Fault Seattle/Toe Jam Hill Fault ZoneZone • Another

USGS LiDAR imaging project that revealed hitherto unmapped Holocene fault scarps

• Common problem in wooded terrain

• AlgorithmsAlgorithms allow for rapid screening of large land areas, allow for rapid screening of large land areas, when combined with neural networks to create an when combined with neural networks to create an artificial intelligence (AI) program to enable discriminate artificial intelligence (AI) program to enable discriminate mapping. mapping.

• AccuracyAccuracy depends on quality and scale of digital depends on quality and scale of digital elevation models elevation models

• Will Will supplant stereopair aerial photographic methodssupplant stereopair aerial photographic methods for for reconnaissance mapping of potential landslide hazards reconnaissance mapping of potential landslide hazards

• LimitationsLimitations would be spelled out on map products, would be spelled out on map products, recommending recommending site-specific investigationssite-specific investigations be employed be employed to determine presence, depth and character of past to determine presence, depth and character of past landslippage. landslippage.

• Property Property would not be “condemned”would not be “condemned” unfit for unfit for developmentdevelopment solely on interpretation of the regional solely on interpretation of the regional hazard map. hazard map.

Topographic AlgorithmsTopographic Algorithms

Recent USGS Landslide MapsRecent USGS Landslide Maps

The USGS has used San Mateo County, CA as their prototype hazard mapping area since 1969. These plots show debris flow hazard map (at left) and landslide incidence map (at right) for Montara Mountain area of northern San Mateo County, CA.

• End Users will demand increasingly detailed assessments. End Users will demand increasingly detailed assessments. Landslide hazard maps generated using GIS can be overlain on Landslide hazard maps generated using GIS can be overlain on tax assessor parcel maps will be used like tax assessor parcel maps will be used like FEMA Flood Insurance FEMA Flood Insurance Rate MapsRate Maps, spreading risk to lenders and insurers. , spreading risk to lenders and insurers.

• Future map productsFuture map products will appear like this, overlaying will appear like this, overlaying map information on DEMs and digital color images. map information on DEMs and digital color images. These products relate well to the general public, These products relate well to the general public, planners, and decision makers. ArcGIS 9.1 product.planners, and decision makers. ArcGIS 9.1 product.