Portland, Oregon
Landslides in the West Hills of Portland pose a hazard to people and property. In February 1996, a major storm caused hundreds of landslides in the West Hills. Smaller numbers of landslides occur every few years during to extended rainy periods and intense storms.
Photograph of cores from borehole B2, loess from top of hole in upper left corner of photograph, cores become successively deeper left to right, texture of weathered volcanic rocks clearly visible in cores at left.
The USGS, in cooperation with Portland State University, and the Oregon Department of Geology and Mineral Industries, has installed monitoring instruments in a hillside in Portland's West Hills. Installation took place during the summer and fall of 2006. These instruments are used to monitor and detect changes in local conditions, including
- Rainfall
- Ground-water Pressure - Tensiometers
- Ground-water Pressure - Piezometers
- Soil Temperature
- Battery
In many landslide prone hillsides, infiltration of water from rainfall or snowmelt increases ground-water pressures. These elevated pressures can, in turn, trigger landslide movement. Measurements are taken at 15-minute intervals and data are transmitted daily and displayed on graphs that are updated daily. Updates may be interrupted occasionally by instrument, computer, or network malfunctions.
Contact Information
-
Jonathan Godt
jgodt [at] usgs [dot] govU.S. Geological Survey
Central Region Geologic Hazards Team
Box 25046, DFC
Mail Stop 966
Denver CO 80225 -
Rex Baum
baum [at] usgs [dot] govU.S. Geological Survey
Central Region Geologic Hazards Team
Box 25046, DFC
Mail Stop 966
Denver CO 80225