March 22 2014, in Oso, Washington, a landslide killed 43 people and injured many more.
Yet in 2006, the Oregon Department of Geology and Mineral Industries declared during a forum about landslides that “collect and analyze LiDAR data [would] help prevent inevitable natural disasters.” After the tragedy of Oso, the government’s vision was to estimate the damage using LiDAR technology.
Indeed, LiDAR is an ideal way to determine the history of a landslide. Because of vegetation and different items covering the floor, using LiDAR help geologists to not only see the landslide, but to collect the clues. So invest in LiDAR remains the first step before discussing the risks of landslides.
In 84% of cases, the human factor appears to be the #1 cause of landslides. A landowner in a risky area can potentially create a situation in which the neighborhood may be affected. For this reason, it is important to know the signs of a landslide problem:
• Structural deformation as large cracks in the foundation, doors and misaligned windows, sloping floors, sunken decks.
• An open crack in a park or on a road.
• Having trouble supporting walls.
• Arcuate Cracks on the ground.
Landslides however often appear after several hours or several days of rain, or after a rapid snowmelt. Earthquakes can also be the cause.
In the United States, the government of North Carolina has a budget of $23 million since 2000 to complete the modernization of flood hazard maps.The approximate cost to complete these surveys ranges from $850/mi2 (to study areas around 50mi2) $430/mi2 (for about 250 mi2 areas). So the biggest the area is, lower is the cost.
LiDAR technology is similar to radar, in fact, it can scan an area with a laser light of energetic particles (photons). During the survey, we collect large amounts of points on which the photons were reflected. These points represent opaque objects, called point clouds. Then the data is stored in the point clouds as X, Y, Z and manipulated in a computer, to create the final elevation record.
During the 2006 forum, the Oregon government estimated that LiDAR surveys would be used to cover areas of more than 10,000 miles, and had thus decided to disseminate the results throughout the State, through federal agencies, counties and cities, private consultants, industries, but also open the data to the public, who can now have access to open source data, such as the Red River scan.