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GIS in Geology: Examining the Geological Change of Mount St. Helens

By Justin Sorensen

GIS (Geospatial Information Systems) are utilized by many fields and industries throughout the world. To highlight some of these fields, our Map Monday releases for the 2019 Spring Semester have provided examples of ways GIS can be employed within the work performed by such professionals.

For this map release, we will look at an example of GIS in Geology.

Examining the Geological Changes of Mount St. Helens

GIS is a powerful tool for examining the world around us. Gathering, analyzing, and visualizing data in a spatial format has the ability to reveal solutions to problems we are researching and answer questions we may not know we have. This type of spatial analysis connects directly with the field of geology, where professionals study the planet’s structure, composition, and change over time. Our final Map Monday release for the semester demonstrates how GIS can be utilized to study a large-scale geological change by comparatively examining Mount St. Helens, before and after the dramatic 1980 volcanic eruption.

As many may know, Mount St. Helens is an active stratovolcano located in the Cascade Mountain Range. On May 18, 1980, a landslide triggered by a 5.2 magnitude earthquake collapsed the north face of the mountain, uncorking the pressurized magma from within and creating a devastating lateral blast that destroyed everything within 230 sq. miles.

To analyze the geological change of the mountain before and after this event, 3D spatial analysis tools can be utilized to compare and visualize changes to the physical structure through the use of Digital Elevation Models (DEM). A DEM allows researchers to examine elevation profiles and visually examine structural changes through a 3D side-by-side comparison. In our examination of Mount St. Helens, we can see that in addition to the physical change of the north face, the mountain experienced a dramatic loss in elevation – approximately 1,314ft (401m).

Additionally, both models can be overlaid to perform a comparison of where the structural loss and gain were the most dramatic. For our examination, a cut/fill spatial analysis was employed to identify material changes between both models (areas of blue indicate a loss of material following the 1980 eruption). Visualizing this spatial comparison through a 3D presentation immediately depicts to both researchers and viewers just how devastating this eruption was, both to Mount St. Helens as well as the surrounding areas.

Following the 1980 eruption, Mount St. Helens continued to experience numerous explosions and lava dome building events, with the last observed eruption taking place on July 10, 2008. The enormous crater stands as a reminder of the devastating power that is still contained within.

When might we see Mount St. Helens erupt again?

Interested in learning more about GIS in other fields? Check out our collection of past Map Monday releases @

About Map Monday from GIS Services:

Throughout the semester, GIS Services has released bi-weekly maps on a variety of topics, demonstrating ideas and uses for incorporating geospatial technology into research and projects you are developing. To view our collection of maps, projects, or to learn more about the geospatial services offered through the J. Willard Marriott Library, please visit the GIS Services website @

Happy Mapping!

Justin Sorensen | GIS Specialist
Creativity & Innovation Services / GIS Services

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