LiDAR technology: a new perspective in landslide risk evaluation

On the occasion of the Oso landslide, LiDAR technology comes forward, as an efficient means of revealing landslide risk. Signs of past landslides were obvious with bare eyes in the Snohomish County, however, a high-end technology would be necessary to evaluate the true magnitude of the slide danger. LiDAR maps generated after the landslide reveal a series of scars and debris deposited along the valley as a result of even larger events occurring in the past. LiDAR technology has been used by USGS for about a decade in the Northwest of the U.S., having mapped about a quarter of the state of Seattle, according to Craig Weaver, chief of the Seattle branch of the U.S. Geological Survey (USGS).

The relatively new LiDAR technology (LIght Detection And Ranging) can produce accurate topographic maps, penetrating through an area's vegetation and provide a detailed picture of the bare landscape, hence revealing a wide range of geological hazards, from earthquake faults to past landslides and flood zones. To generate a map, an airplane equipped with special lasers, flies over the mapping area, in a grid, sending over 150,000 light pulses per second to the ground. Depending on the travel time of each pulse, a computer program discards the signals which hit on trees and buildings and produces a representation of the bare landscape within a few inches accuracy.

The indisputable LiDAR importance is stressed out by University of Washington geologist David Montgomery in that "Lidar is like a new pair of glasses. If you can see more, if you have better data, you can better assess the true risks". However, it is equally important to evaluate the acquired data and communicate solid and usable information out to the public. Otherwise, "it's just nice data".