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Why study landslides? 🚨
Landslides are a major global hazard, often triggered by heavy rainfall. These events threaten both lives and infrastructure, and have claimed thousands of lives worldwide. Regions such as Central and South America are particularly affected due to their high susceptibility to intense rainfall and the presence of large populations living on or near steep slopes.
2011 landslides in La Paz (Photo from BBC News Mundo 02/28/2011)
Mud Creek landslide (CA) changes from March 2017 to June 2018Â (Photog. Andy Richtier for USGS)Â
... And why focus on slow-moving landslides (SMLs)? 🤔
Fatalities are usually associated with catastrophic landslides, which can travel downslope at speeds of tens of meters per second. SMLs, on the other hand, deform much more gradually, at rates ranging from just a few millimeters to several meters per year. However, they can still cause significant infrastructure damage and have the potential to suddenly transition into catastrophic events, often with little or no warning!
Areas of interest: the Americas
Because SMLs deform so gradually, they can go undetected for long periods, especially in regions without active monitoring networks. Some regions in the Americas are particularly vulnerable to SMLs due to their high susceptibility to heavy rainfall and large populations living on steep slopes.Â
Population density, annual average precipitation and slope steepness across the Americas. Green areas show locations of reported landslides in NASA’s COOLR repository, with a clear underreporting of landslides in South America (Image from own work).ier for USGS)Â
Remote sensing: InSAR
Remote sensing: InSAR
Interferometric Synthetic Aperture Radar (InSAR) has been a useful tool to identify suspected SMLs across broad areas through the analysis of temporal and spatial deformation variations.
InSAR uses pairs of SAR images from the same area taken at different time. Phase differences between images indicate where the distance to the target has changed from one pass to the next, allowing us to quantify surface deformation!
Interferometric Synthetic Aperture Radar (InSAR) has been a useful tool to identify suspected SMLs across broad areas through the analysis of temporal and spatial deformation variations.
However, it is still challenging to separate SMLs from other deformation signals without utilizing complementary topography-based analyses.
DEM
DEM
Using Digital Elevation Models (DEM) it is possible to compute the slope, curvature and other features of the terrain. These information can help us understand where SMLs are located!
Slumgullion landslide, CO (from opentopography.org/lidarlandforms)
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