Debeque Instrumentation

This web page allows one to view the movements recorded from instruments installed as part of an investigation of the Debeque Canyon Landslide by the Colorado Geological Survey on behalf of the Colorado Department of Transportation. This ongoing investigation was initiated after major movements damaged Interstate 70 in April of 1998. Movement data on this webpage was recorded from 1999 to 2011.

Use of this page

Ground-movement graphs of the various tools are linked to the annotated oblique aerial image. Clicking on the tool location shown on the annotated image will link to the data.

DeBeque Canyon Landslide. Photo by J. White

Listing of Tools

The following tools listed below are available for observation:

  • Manually-read prisms 1 through 15. These prisms are surveyed by a robotic total station from across the river. The station location was selected so the approximate landslide movement was towards it. The linked prism data is in MS Excel files that include a survey data spreadsheet and scatter graphs that show movements over time.
  • Manually read inclinometers in borings DLS-2, DLS-3, DLS-4, and GAI-1. This data is shown in graphs generated by Slope Indicator DigiPro software.
  • Inclinometer readings at borings GAI-4, GAI-6, and GAI-7 are no longer available. Early landslide movements deformed and ultimately sheared the installed inclinometer casing.

Comparative movement since 1999

Open this file to view a comparison of movement magnitudes at the various prisms. The data shown in this file is the cumulative change in raw slope distance, measured directly by laser.

Vector images

Click on thumbnail below for calculated vectors of prism movements projected on an aerial photograph.

Vector Prism Movements

In addition to the above tools, the USGS has provided periodic GPS monitoring of certain survey monuments installed on the landslide. Click the image below to view vector landslide movements based on previous GPS monitoring.


Survey Prism: An optical prism that is used for surveying by precisely reflecting a laser beam back to a survey instrument. The survey instrument, called a Total Station, can accurately measure slope distance and changes in angle. Using this data, the spatial location and elevation of the prism can be calculated in the survey coordinate system. Movement vectors can then be determined by comparison from initial baseline readings to later readings. The prisms are anchored onto the rock face with the prism directed towards the survey base station that is located across the Colorado River from the landslide.

Manual Inclinometer: Inclinometer tools can precisely measure the change in deflection or tilt of a casing pipe, installed and cemented into a drill hole that extends through the landslide deposit. The inclinometer probe has small wheels, and when manually lowered into the casing by a data cord, slides into casing slots to orient the tool. Its primary use is to determine at what depth(s) ground movements are occurring. Sequential readings over time provide comparison of the relative tilt at discrete depth intervals. This data can then provide information on the magnitude and rate of ground movements. In a moving landslide, the casing will ultimately shear at a ground depth called the landslide slip plane. That is the underground boundary between moving landslide debris and intact bedrock or soil. The manual inclinometers used at the DeBeque Canyon Landslide include electronic, vibrating-wire types.