Landslide Maps

Showing comparison of the modeled earthquake triggered landslide distributions for the 04/25/2015 Mw 7.8 mainshock and the 05/12/2015 aftershock in Nepal. (Data used SRTM digital elevation model; USGS ShakeMap; version 7 for mainshock and version 3 for aftershock). More data will be posted in the upcoming days.
[analysis by Sean Gallen; posted 05/12/2015]

Landslide dam hazard map based on a Newmark displacement analysis using peak ground accelerations (PGA) from USGS ShakeMap version 6 and Shuttle Radar Topography Mission (SRTM) 90 meter topography. The hazard window is limited to the extent of the 10% g PGA contour.  Analysis by Marin Clark, Sean Gallen, and Nathan Niemi. A KMZ file of at-risk stream channels is attached at the bottom of the page, or can be retrieved from the Downloads page. Yellow pushpins indicate locations where landslides have been reported or seen in satellite imagery. 

Note: We are updating our results often and posting them on the Downloads page.

Low risk
High risk
Blue stars are observed locations of landslide dams that blocked river valleys, as observed from aerial surveys in Collins and Jibson (2015), USGS OFR 2015-1142.
 

Landslide Dam Hazard Analysis




Contour map of predicted mean landslide volumes and thicknesses. The map is based on a modified Newmark analysis described in Gallen et al. (2015). The data used to generate this map include peak ground accelerations (PGA) from USGS ShakeMap version 6 and Shuttle Radar Topography Mission (SRTM) 90 meter topography.

Predicted mean landslide thickness and volume contour map



Revised landslide volume and depth calculations have been made. Based on observations from satellite images and reports from the ground, we have revised our predicted landslide maps. Below are a series of images of our model data smoothed using a 5 km^2 moving window. Our previous model results are shown below for comparison. The kmz file of both maps are available for download at the bottom of the page ("smoothed landslide thickness and volume_update.kmz" is this file). I have also included a kmz file (depth_ct12.kmz) of the original landslide polygons color coded by mean depth (cooler = shallower, warmer = deeper).


Older smoothed landslide volume and depth predictions

Google Earth Figure

Google earth image with an over lay of predicted mean landslide thickness (depth) and volume. The model used to produce this image is a modified Newmark analysis (see Gallen et al., 2015 for the full model description). The data used was SRTM digital topography (~90m resolution) and the peak ground acceleration model from the USGS ShakeMap. This data represents a model output based on an assumed "moderate" rock strength scenario. This map shows model predictions and it not an actual visualization of landsliding during the earthquake.

You can download this Google Earth overlay below, just select the file "predicted mean landslide thickness and volume.kmz". The color scale of the kmz file is the same as in the figure above. [Created by Sean F. Gallen, 04/30/2015]



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Landslide Dam Hazard.kmz
(2851k)
Nathan Niemi,
Apr 29, 2015, 11:42 AM
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depth_ct12.kmz
(3081k)
sfgallen@umich.edu,
May 2, 2015, 7:45 AM
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mod_strength_polygons.kmz
(3081k)
sfgallen@umich.edu,
May 6, 2015, 8:40 AM
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predicted mean landslide thickness and volume.kmz
(384k)
sfgallen@umich.edu,
Apr 30, 2015, 10:51 AM
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smoothed landslide thickness and volume_update.kmz
(285k)
sfgallen@umich.edu,
May 2, 2015, 7:44 AM
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vol_thickness_contour.kmz
(178k)
sfgallen@umich.edu,
Apr 30, 2015, 2:41 AM
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