Measuring Landslides

One of the most important aspects of studying landslides is determining if the slide is moving, and, if so, the rate of movement. This is especially important in montitoring slides which have a history of reactivating periodically. Geologists use a variety of instruments to collect date regarding the slide. Sensors collect data on rainfall, groundwater (pressure sensors), movement (displacement sensors) and ground vibration (geophones). GPS units are also used to measure movement and to determine the dimensions of the slide. (

Interactive Imagemap, California Landslide Monitoring
Testing the solar-powered radio telemetry system used for real-time monitoring. -- USGS Photo by Mark Reid, USGS/Menlo Park (
Measuring landslide movement using a surface extensometer. Extensometer crosses several scarps (breaks that expose the reddish soils) at the head of the landslide. -- USGS Photo by Richard LaHusen, USGS/CVO (
Caltrans drill rig installing subsurface extensometers (to measure landslide movement) and pore-water pressure sensors (to measure ground-water conditions) in the Mill Creek landslide. -- USGS Photo by Mark Reid, USGS/Menlo Park (