Landslide Assistance from the Air

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The USGS uses cutting edge technologies to investigate and forecast landslides and other natural hazards.

Lidar, which is short for “Light detection and ranging”, is a remote sensing method of studying the Earth and surface characteristics. This technology, often from aircraft, uses light in the form of laser beam pulses to measure ranges and distances reflected from the ground.  These thousands of pulses per second are translated into highly accurate and precise elevation data.

Sample graphic of airborne lidar data acquisition
Sample graphic of airborne lidar data acquisition. Target area is illuminated by pulsed laser light from sensors in the aircraft. Differences in laser return times and wavelengths are then used to make digital 3D representations of the selected ground sections.(Public domain.)

The USGS uses lidar, and in some cases as similar tool called IfSAR ( Interferometric Synthetic Aperture Radar) as part of a national elevation database named the 3DElevation Program, or 3DEP.  The 3DEP goal is to collect and release enhanced elevation data for the entire nation.

With this technology, the USGS Landslide Hazards Program can conduct landslide hazard assessments, pursue landslide investigations and forecasts, and provide technical assistance to respond to landslide emergencies. Lidar can penetrate vegetation, helping scientists find hazardous areas and evidence of previous landslides that are otherwise hard to spot under forest cover.

Research on landslide processes addresses critical questions of where and when landslides are likely to occur as well as their size, speed, and effects. This understanding informs the development of methods and tools for hazard evaluation and awareness used to assist efforts to avoid or mitigate landslide impacts. Such research is essential for the USGS to provide improved information on landslide potential associated with severe storms, earthquakes, volcanic activity, coastal wave erosion, and wildfire burn areas.

For example (see below), during the Oso, Washington landslide in 2014, geologists were able to compare lidar collected before and after the event to provide information to emergency responders about the depth of the landslide debris.

Decision makers in government and the private sector increasingly depend on information the USGS provides before, during, and following disasters so that communities can live, work, travel, and build safely. 3DEP provides the programmatic infrastructure to generate and supply lidar-derived superior terrain data to address landslide applications and a wide range of other urgent needs nationwide. By providing data to users, 3DEP reduces users’ costs and risks and allows them to concentrate on their mission objectives.

More information can be found from the recently published “Landslide Recognition, Hazard Assessment, and Mitigation Support” Fact Sheet.

Aerial graphic of Oso landslide
Aerial photo of the Oso, Washington landslide in 2014. The red arrows show the direction of material flow. The inset lidar image was derived from 3DEP data collected by the Washington Department of Transportation.(Public domain.)