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Geologic Monitoring

Slope Movements

Photo of Yosemite National Park Landslide
Landslide covers a roadway in Yosemite National Park, California.

What are slope movements?

Slope movements refer to the downslope transfer of soil, regolith and rock under the influence of gravity. Slope movements may occur over seconds or even years. Some examples include:

Why does the National Park Service monitor slope movements?

Collection of data on regional slope movements is beneficial for

  • assessment of landslide hazards and risk,
  • which is in turn important for park operations and planning.

  • Monitoring Book
  • Resource Facts
  • Case Study

Geological Monitoring Book

Vital Signs Monitored

  1. Types of landslides
  2. Landslide triggers and causes
  3. Geologic materials in landslides
  4. Measurement of landslide movement
  5. Assessing landslide hazards and risks

Chapter 11
Monitoring Slope Movements (PDF - 1.88MB)

Slope movements, including landslides and extremely slow soil creep occur throughout the United States and within many national parks. The collection of vital signs of regional landslide information, referred to as monitoring, is not only scientifically useful, but is beneficial for assessment of landslide hazards and risk, which is in turn important for regional operations and planning.

This chapter will describe several different methods of monitoring slope movements to evaluate landslide hazards and risks.

NPS Slope Movement Facts

Geologists use the term "mass wasting" for slope movements as described above.

Mass wasting effects can be seen in every state and in every national park.

More than 400 rockfalls have been documented in Yosemite National Park.

In 1996, a rockfall at Yosemite National Park generated an airblast with a wind speed comparable to a hurricane (~250 mph), which caused about a thousand trees to snap in the area.

Monitoring Slope Movements in the National Park Service

Monitoring Rock Fall Activity at Yosemite National Park

Although predicting rock falls is not yet possible, documenting and understanding the events that happen is an important step toward this goal.

Vital signRationaleMethod
Changes in cliff morphology:Can determine locations and volume of rock fall, and pre-failure geometry of cliff faceRepeat LiDAR scanning coupled with high-resolution photography
Atmospheric conditions:Air temperature and humidity can affect stability of slopesDirect observations / field measurements
Exfoliation joints:Exfoliation joints dictate rock fall locationsField mapping & in-situ stress measurements

Additional Information
Yosemite Panoramic Imaging Project
Yosemite Science Publication - High-resolution Tools for Understanding Geologic Processes (PDF - 380 KB)

Related Links



Last Updated: January 03, 2017