An Early Warning System for Landslide Danger

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An Early Warning System for Landslide Danger

Advances in satellite imaging, mapping, and rainfall estimations have made it possible to implement a regional real-time assessment of landslide hazard threats.  

bYsfwWH.jpgLandslides are one of the costliest and deadliest natural phenomena in mountainous regions.

Between 2007 and 2015, 7000 rainfall-triggered landslides around the world killed more than 25,000 according to NASA’s Global Landslide Catalog.

The U.S. Geological survey estimates that costs from these events could reach $4 billion or more each year.

Landslides are also one of the most difficult natural disasters to predict because the factors that affect slope stability vary dramatically in both space and time.

However, dramatic advances in precipitation estimation, high-resolution imagery, and elevation maps are advancing our ability to predict the threat of rainfall-triggered landslides in real time.

Applying these advances to landslide prediction, especially in developing areas of the world, could save countless lives and direct resources to where they are most needed for landslide prevention and recovery.

To help with efforts to develop a prototype for landslide prediction, the Hydrologic Research Center (HRC), a nonprofit research corporation, set out to develop a landslide hazard threat assessment for Central America. We focused on the nations of Central America because of the strong regional partnerships already in place there, as well as the availability of relevant data.

Our approach involves including landslide threats in flash flood guidance threat assessments. We got our first opportunity to validate our threat assessment system in October 2015, when a major landslide occurred in an area of Guatemala that we had flagged as an area of very high risk during that time period.

MPGZ4tD.pngThe Science of Assessing Landslide Hazard Threats

Predicting the temporal and spatial occurrence of rainfall-triggered shallow landslides represents an important scientific and practical issue.

Intrinsic factors (topography, geology, soil, and engineering properties) and extrinsic factors (rainfall, land cover, fire, glacier outbursts, earthquakes, and volcanoes) control slope stability and landslide triggering.

The likelihood of a landslide is also affected by the nonuniform nature of the structural forces that hold a slope together and the physical mechanisms that trigger the landslide.

Landslide hazard threat assessments are segregated in both space and time—each assessment is separate unto itself. Spatial threat assessments (susceptibility maps) are derived in one of two ways: using spatially distributed parameters (e.g., slope, geology, precipitation totals) to assign a weight to individual pixels in a grid or using a database of existing landslides, along with spatially distributed parameters, to derive weights using a variety of statistical methods.

Aims of the Assessment

Predicting the threat of rain-induced landslides is imperative. A recent review shows that 90% of all recorded landslides in Latin America and the Caribbean were triggered by heavy rainfall, which increases the amount of moisture in the soil [Sepulveda and Petley, 2015].

This review found that between 2004 and 2013, about 2730 people died in 128 landslides in Central America. Of the landslides that were triggered by rainfall, 15% were associated with named tropical storm events. Only 4% of landslides were earthquake induced, and the remaining 6% were associated with construction or volcanic activity.

To help mitigate this high level of risk, our assessment has three main goals:

Read full article at: Earth and Space Science News

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