3-D NATURAL HAZARD MAPS FOR PORTLAND, OREGON

Hazard maps have been produced for many years, but now modern graphics allow them to be produced in three dimensions. One essentially combines the hazard delineations with digital elevation maps and convert them to the red/green colors for the 3-D effects. One needs the standard 3-D glasses to see the relationships between topography and natural hazards. Some maps really make sense when seeing them in 3-D. First, two 3-D maps at different scales of the Portland area are used to show landform delineation and landscape evolution. Faults, volcanoes, stream terraces and Missoula Flood deposits are easily picked out. Flood hazard maps are easily understood in 3-D because the lowest places are the most flood-prone. The landslide hazard maps plot past landslides, and they seem to be most prevalent on the steepest slopes. Earthquake hazard maps show responses of the ground to earthquake waves, and faults really show up as lineations on the 3-D maps. Volcanic hazard maps of nearby Mt. Hood again are the most prevalent in the lowest elevations where debris flows (lahars) can move. Radon is the only hazard map that does not have a clear relationship to elevations expressed on the 3-D map. Special glasses will be passed out to the audience to allow them to see the maps in 3-D.