By now, everyone in the Bay Area knows about the Did You Feel It? system, set up by the U.S. Geological Survey in the 1990s to record earthquake reports. This week the Survey has launched a similar effort, called Did You See It? or DYSI, to enlist citizens in recording landslides. Bay Area residents should take to this tool enthusiastically because we live in landslide country as well as earthquake country. In fact, earthquakes so often cause landslides that conscientious folks can now make twice the contribution after a seismic event.
The earthquake tool has succeeded so well because, among other things, the facts it needs to know are easy to check offwhere you were, what things you noticed, what was damaged. The new landslide tool works a little differently because landslides aren't the same kind of event. Reporting a landslide on the DYSI tool takes a bit of observation.
Landslides are classified along a spectrum between falls and flows. They involve three kinds of material: earth (soil), debris (rocks and soil) and rocks. Rockfalls, like this example from the Marin Headlands, should be familiar. They're basically a rattle of rocks.
Flows include earthflows and debris flows. They have a fluid motion and shape, like this example, a debris flow from the Marin Headlands.
Slumps, or rotational slides, are in-between landslides with a sitzmark shape. This one is in the Oakland hills.
Those three are the most common landslide types around here. The DYSI tool shows four additional landslide types, and if you hold your mouse over each one a rotation of diagrams and photos will display them to you. Even better, you can right-click to view these at full size. The tool has options to accept much more detail (like loss data and your photos), but that's the gist of it.
Because landslides are more widespread than quakes, "Did You See It" may provide even more benefit to the nation than "Did You Feel It."