Mount St. Helens before 5/18/80 eruption
(Data now available as Historic DEM)
Mount St. Helens after 5/18/80 eruption
(Data available in National Elevation Dataset)
The United States Geological Survey (USGS) maintains a large inventory of elevation data
produced from source maps and photographs of varying vintage. Digital elevation models
(DEMs) from older sources have the potential to describe a historic land surface. This
product consists of nearly 13,000 discrete, native format USGS DEMs, which would otherwise
Typically, there are several DEMs available per quadrangle area. For this product, the best
of the oldest DEMs are selected. Only better "level 2" data are selected with the notable exception
of a pre-eruption DEM of Mount St. Helens, WA, which was produced by the manual profiling technique.
A select historic DEM may be as little as one year older than a more current version of the same DEM.
The specific DEMs chosen reflect current inventory, and is subject to change.
Unlike DEMs used to populate the National Elevation Dataset, these DEMs have not been reviewed for
quality, and have not been subjected to corrective filtering or edge matching. They may on occasion
exhibit spurious values or may be coded in incorrect units. Further, DEMs with older source dates may
show little difference in content. More often, only a quality difference is observed. These data are
provided on speculation of historic content only.
For further assistance or to obtain data, please contact National Map Help