Landslide Hazards

Landslides, debris flows, and rock falls are hazards to humans and infrastructure at many of the nation's park units. For example, in February 1995, a 1,600-foot stretch of popular beach at Sleeping Bear Dunes National Lakeshore suddenly slid into the waters of northeastern Lake Michigan. The National Park Service (NPS) immediately requested the assistance of the U.S. Geological Survey (USGS) in evaluating the hazard at the lakeshore. To protect the public, USGS and NPS scientists conducted studies that will help predict when the landslide-prone area will move again.

Pictured above: Sleeping Bear Point at Sleeping Bear Dunes National Lakeshore.

USGS and NPS scientists believe that repeated coastal landslides at Sleeping Bear Point may be related to increases in fluid pressure in the spaces between the grains of sand (pore pressure) that make up the bluff at the point. The increased amount of water would weaken the slope, making it susceptible to landslides. To test this idea, instruments to measure the pore pressure (piezometers) were installed within the bluff.

Pictured above: A USGS scientist installing a piezometer.

USGS scientists are also using information from Global Positioning System (GPS) satellites to detect any movement that might indicate instability. In 1997, USGS scientists conducted studies of the underwater part of the 1995 slide from a small ship. They also found a thick blanket of debris from the slide extending more than 2 miles offshore, indicating an extensive history of landslide activity within the area.