Digital Elevation Map of Mount St. Helens pre and post 1980
The shaded relief image was produced from LIDAR data. LIDAR is an acronym for Light Detection and Ranging, a modern remote sensing technique used to map topography very accurately—more so than is possible with older techniques. The crater is 1.2 miles (1.9km) wide east-west. Elsewhere the scale varies owing to the oblique viewing angle. The landslide deposit includes the hummocks deposited to the northwest, and the location where the debris avalanche ruan-up a steep south-facing slope (bottom of image). The pumice plain is the location of a large fallout deposit from the Plinian phase of the eruption. Age of the domes in the center of the crater is indicated in the call-out text.