Old Sticks in the Mud: Hazards of Lahars from Mount Rainier Volcano

Patrick Pringle, Centralia College
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Initial Publication Date: October 9, 2012 | Reviewed: July 6, 2017


A thematic "big idea" for these exercises as related to geological processes is that volcanic debris flows (lahars) can flow long distances, bury and aggrade river valleys, and cause long-term stream disturbances and dramatic landscape changes. The big idea related to sustainability is that humans are connected to Earth systems and thus, to nature.
Several activities can be done individually or in sequence by students in one class over time. To prepare for these activities, the students will first read a US Geological Survey (USGS) overview about volcanic hazards and then USGS Fact Sheet 2008-3062 by Driedger and Scott (2008) which will help them answer a series of questions about Mount Rainier's hazards. An initial reading activity is based on "The lake on Mount Rainier", a short oral history of the Puyallup Tribe related by Ella E. Clark (1953) and/or on a different version of this oral history, "A young man's ascent of Mount Rainier (first version)" by Arthur Ballard (1929). A later, perhaps final reading activity will consist of reading online materials about the eruption of Nevado del Ruiz volcano in Columbia in 1985, which killed 23,000 in the town of Armero. That town is the same distance from Nevado del Ruiz as Orting, Washington is from Mount Rainier. The lab activities will include using diagrams prepared by geologists to calculate landscape changes in valleys downstream of Mount Rainier over geologic time. Such changes include the progradation of shorelines through geologic time, the amount of new land area produced by volcanic sedimentation, approximate volumes of volcanic debris, and changes in the channel length and stream gradient caused by the deposition of past lahars and lahar-derived sediments.

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Learning Goals

1. Compare and contrast volcanic eruption styles, products, processes, and hazards
2. Measure the amount of aggradation through time in a valley draining the volcano and estimate volumes of transported volcanic sediment
3. Measure changes in channel length and calculate changes in stream gradient owing to stream piracy after a catastrophic volcanic event
4. Describe and map the risk of lahars and floods
5. Describe factors, processes, and interactions that are responsible for lahars and floods
6. Evaluate the broad implications of volcanic and flood hazards information on traditional, historic, and current land uses and users; on governmental and quasi-public institutions and representatives; on individuals and corporations; on property rights and economic concerns
7. Evaluate the roles of the scientist, educator, public official, and individual in addressing the ethical and social responsibilities or implications of geologic hazards information
8. Devise strategies that the individual and institutions can adapt or pursue in order to reduce the risk of geologic hazards such as lahars and floods
9. Explain the role of science in understanding, forecasting, and predicting hazardous natural processes such as lahars and in mitigating the risk

Context for Use

These lab activities are relevant for introductory classes with labs such as Physical Geography, Physical Geology, and Natural Hazards. The lab activities are suitable for groups of students up to about 24, but preferably fewer in number. The individual activities can be broken up into separate lab sessions.

Skills and concepts that students must have mastered

The students should be familiarized with an overview of volcanic processes and types of volcanism. This information can be found in Pringle (2008) and at various websites such as the following:

How the activity is situated in the course

The lab activities are introduced via reading assignments and lectures given in the week before each activity or lab. The students first read fact sheets and information written by geologists who have compiled the most recent documentation about the nature and history of the volcanic events from Mount Rainier and the types of volcanic processes involved and areas impacted. The students then read stories that are transcriptions (or summary paraphrasings) of oral histories of native peoples who lived near Mount Rainier. Lastly, the students would read about the disaster at Nevado del Ruiz volcano in Columbia in 1985 and compare the scale and effects of that eruption and lahar to the potential for future disaster's at and downstream of Mount Rainier (or other snow/ice clad volcanoes).

Description and Teaching Materials

Activity Description/Assignment:


Volcanic debris flows (lahars) flow long distances, bury and aggrade river valleys, and cause long-term stream disturbances and dramatic landscape changes. The same valleys may be affected by floods, which occur more frequently, but are typically smaller in scale. Students will evaluate the nature, scale, and history of past lahars from Mount Rainier in a river valley and interpret the past and potential future impact on humans of lahars.

Introductory reading assignments:

The following reading assignments will prepare the students for lab activities. These can be given during the week before the lab(s). Another optional activity to prepare students for the labs portion is to have them complete the modules for the math you need, when you need it at the SERC website.

1. Ask the students to read the US Geological Survey Fact Sheet 002-97 What are volcanic hazards?. This fact sheet is a good overview of the different kinds of hazardous volcanic processes that one could expect from a large composite volcano like Mount Rainier. Ask them to compile a list of each type of volcanic hazard and to note how each hazardous process may behave (how far from the volcano might they have an effect, how often, notable examples, etc.). Note: similar information can be found at http://volcanoes.usgs.gov/hazards/.

2. Next ask the students to read through US Geological Survey Fact Sheet about Mount Rainer, http://pubs.usgs.gov/fs/2008/3062/ by Driedger and Scott (2008).

a. What is a lahar and how can it be formed? In what ways does it differ from a flood?

b. How does a meltwater-triggered lahar differ from a landslide-generated lahar in terms of their composition, behavior, and how they are formed?

c. How can lahars travel so far, and so fast?

d. Look at the summary hazards map "Hazard zones for debris flows, lahars, lava flows, and pyroclastic flows from Mount Rainier." Explain to a lay person how lahar hazards are localized or constrained by physiography and scale.

3. Next ask your students to read The Lake on Mount Rainier, a short oral history of the Puyallup Tribe related by Ella E. Clark (2003). Ms. Clark was Professor of English at Washington State University in Pullman. The story is an allegory that describes a lake draining and a great "flood" event that swept trees away and covered the Puyallup River valley with stones. Without explaining what the oral history means, inform the students that the stories predate any detailed documentation and dating of the eruptive activity at nearby Mount Rainier. Clark's is but one version of the story. Instead of using this version, or as an optional additional assignment, have the students read at least two versions of this story entitled The young man's ascent of Mount Rainier found on p. 142--144 by Arthur Ballard (1929). [If copyright restrictions are an issue, the teacher can prepare paraphrased summaries of the aforementioned oral histories].

Essay questions on the readings of the oral history (points can be assigned for each answer):

a) What do you think the various forms of symbolism mean about how the mountain, Mount Rainier, was perceived?

b) How do we know the mountain described is Mount Rainier?

c) What are the references to time, and what might they suggest about the events being described?

d) There is a reference to water from a lake on the mountain rushing down, sweeping away trees, and leaving behind porous stones. Having read about types of volcanic processes and hazards, what is does the story signify?

4. The next activity will consist of reading online materials about the eruption of Nevado del Ruiz volcano in Columbia in 1985, which killed 23,000 in Armero and neighboring towns. Notably, Armero is the same distance from Nevado del Ruiz volcano as Orting, Washington is from Mount Rainier, about 50 km or 30 miles! Students should be encouraged or assigned to read the following websites that contain information about the 1985 Nevado del Ruiz eruption and lahar:



5. An optional final reading activity is to read Mt Rainier Volcanic Hazards Response Plan:http://www.emd.wa.gov/plans/documents/mtrainier_volcanic_hazards_response_plan.pdf.

Integrative assignments

The following activities will allow students to measure landscape changes through time in an area impacted by past volcanism.

Tools needed: Google Earth or GIS software and/or lahar hazard maps or diagrams (see references and links). The lab activities will include using diagrams prepared by geologists to calculate the amount of progradation of shorelines through geologic time, the area of new land area produced by volcanic sedimentation, the approximate volumes of volcanic debris, and changes in the channel length and stream gradient caused the deposition of past lahars.

Activity 1: Calculate rates of delta progradation for paleo-shorelines through time. The students should show all calculations and units. The four different methods, a, b, c, and d, are each separate exercises. They can be done as sequential activities, or individually. One alternative would be to have individual teams of 3--4 students work on separate methods of quantifying the landscape changes.

Diagram 1. Puget Sound shoreline changes since the Osceola Mudflow (Pringle, 2008), modified from Dragovich and others (1994). Diagram 1. Click image to enlarge.
a)Simple method: Examine diagram 1 that shows Puget Sound shoreline changes since the Osceola Mudflow (Pringle, 2008). Use a ruler and the scale shown on the map to estimate the distances that the Puget Sound shoreline has moved in the Puyallup River valley and the Duwamish River valley since the Osceola Mudflow about 5,600 yr ago.

b) Google Earth method: by examining the diagram above and using Google Earth, estimate the same distances mentioned in part a above.

c) Using Diagram 2, calculate the rate of aggradation for the two time intervals shown using the radiocarbon ages and using approximate distances from the cross section (Diagram 2). This diagram was modified slightly from one constructed by geologist Paul Zehfuss, who conducted a more detailed study of shoreline changes in the Duwamish River valley. Point A shows the location of the Puget Sound shoreline in the Duwamish-Green River Valley about 5,600 years ago before the Osceola Mudflow, point B shows the location of the shoreling about 2,200 years ago, and point C shows the shoreline today.

d) After completing the measurements above, the students can be asked to compile a forecast speculating and roughly quantifying what the nature of future landscape changes might be at times into the future given the eventually likelihood of future volcanic eruptions at Mount Rainier.

Diagram 2. Cross section of Duwamish valley Diagram 2. Click image to enlarge.

Activity 2: Based on Diagram 1, which shows a paleogeographic view of a portion of the Puget Lowland 5,600 years ago just before the great Osceola Mudflow from Mount Rainier (1-A), and today (1-B), use Google Earth or a GIS program to do the following: (The students should show all calculations including unit conversions).

a) Calculate changes in surface area of "new land" (post Osceola Mudflow) owing mostly to lahars and lahar-derived flooding through time.

b) Calculate changes in stream length pre-, and post-Osceola Mudflow and evaluate the following effects of the dramatic stream piracy caused by lahar inundation: The pre-Osceola White River flowed from near present day Buckley and Enumclaw (~47.144700, -121.950700) to the southwest along the present course of South Prairie Creek and to join the Carbon River and then flowed into the Puyallup River valley near Orting. From there it flowed north toward present day Auburn and entered Puget Sound at about 47.250 north latitude. Immediately after the Osceola Mudflow, the channel of the White River cut to the northwest from near the same location near Buckley and Enumclaw (~47.144700, -121.950700) and entered Puget Sound near (47.300, -122.218) at Auburn.

c) Using Google Earth to get elevations and cross-valley and longitudinal profile dimensions, crudely estimate the volume of sediment that was removed by the post-Osceola White River to create the canyon that exists today between Buckley/Enumclaw and Auburn. Those who have access to GIS software can use 3D spatial analysis techniques to acquire a more precise volume. Assuming the lower Duwamish River valley between Auburn and the Port of Seattle is same general shape as this canyon in cross section and that the post-Osceola fill in that reach averages 60 m, what is a crude volume estimate for this reach and how does that volume compare with the volume removed from the reach between Buckley/Enumclaw and Auburn? A similar measurement of post-Osceola volume could be made for the reach of the Puyallup River valley between what is now the City of Puyallup and Commencement Bay at Tacoma.

d) After completing the measurements above, speculate on possible sources of sediment needed to account for the present volume of sediment in these reaches, given that that published volume of the Osceola is ~3.8 cubic km or slightly greater.

Activity 3: Here is an optional activity based on the readings, including Mount Rainier volcanic hazards plan. Arrange an in-class role-playing activity in which student groups take the roll of volcanologists, land-use planners, land owners, emergency managers, and other citizens who might be affected in downstream areas or near the volcano.

Final Activities

Write a report summarizing the past eruptive history and analysis of your data, and discussing implications for future changes and human use of the affected river valleys including the probabilities for future inundation by lahars and aggradation of the valley bottom.

Students who have read Mount Rainier volcanic hazards plan and/or who participated in the role-playing activity should prepare a write-up in which they summarize the "lessons learned" during the role-playing activity. As a further discussion they should speculate using on how the role of the geologist differs from the role of the land-use planner, the emergency manager, the teacher, the mayor of a town in the hazards zone, the teacher in school in the hazards zone, or a parent?

Teaching Notes and Tips

The reading and lab activities here are intended to be spaced over at least two or three class/lab sessions. They can also be done individually in an "a la carte" style.
One of the big challenges for students learning science is absorbing the rich vocabulary. For this reason it is important that they read the USGS fact sheet on hazardous processes first. A valuable additional alternative for those teachers who have the time is show the class the instructive UNESCO video. "Understanding Volcanic Hazards" first.
For the writing assignments prepare a rubric that includes points for using citations to the readings and web links (both those noted herein and elsewhere).


1) The students can be tested on the "What are volcanic hazards?" reading assignment by giving them a quiz to see if they have learned the vocabulary and understand the nature of the respective volcanic processes.
2). Students who read Driedger and Scott's "Mount Rainier: Living Safely with the Volcano in Your Backyard" can be assessed on the following points either via essay or multiple choice questions:
a) Do the students know the terms that describe different kinds of volcanic processes, and can they understand what information is needed to complete an assessment of hazards? Finally, can they roughly reproduce the hazards map showing the areas that may be impacted by future pyroclastic flows and tephra fallout, small debris flows, lahars, and laharic floods?
b) Can students associate volcanic risk from lahars with locations of population centers and development and infrastructure near the volcano?
c) Can students describe how two types of lahars could form and how the great amount of snow and ice on Mount Rainier (~ 1 cubic mi) could contribute to these hazards?
3. Some example test questions on volcanoes, volcanic processes, and volcanic hazards are shown in Example test questions on volcanoes, volcanic processess, and volcanic hazards (Microsoft Word 41kB Aug19 11)
4. Students who completed one or more of the measurement activities can be assessed based on how well they recorded their mathematical calculations including units and the accuracy of their results.
5. Students who read the Mount Rainier volcanic hazards plan and who participate in the role-playing exercise should be assessed based on how well they understand the spatial limitations and behavior of respective volcanic processes and how accurately they integrate the web and literature citations into their write up. Questions such as those in Example test questions on volcanoes, volcanic processess, and volcanic hazards (Microsoft Word 41kB Aug19 11) can be used here as well.

Do the students understand the difference between forecasts and predictions and how each are derived? Part one of Pringle (2008) explains the difference. Several of the test questions in Example test questions on volcanoes, volcanic processess, and volcanic hazards (Microsoft Word 41kB Aug19 11) can be used to assess their understanding of these concepts.

References and Resources

References and resources

Ballard, A. C., 1929, "Mythology of Southern Puget Sound." University of Washington Publications in Anthropology, v. 3, no. 2, p. 31-150.

Clark, E. E., 1953, Indian Legends of the Pacific Northwest. University of California Press [Berkeley], 225 p.

Dragovich, Joe D.; Pringle, Patrick T.; Walsh, Timothy J., 1994. "Extent and geometry of the mid-Holocene Osceola mudflow in the Puget Lowland--Implications for Holocene sedimentation and paleogeography." Washington Geology, v. 22, no. 3, p. 3-26. http://www.dnr.wa.gov/Publications/ger_washington_geology_1994_v22_no3.pdf

Driedger, Carolyn L., and Scott, William E., 2008. "Mount Rainier; Living Safely with a Volcano in Your Backyard." U.S. Geological Survey Fact Sheet 2008-3062 http://pubs.usgs.gov/fs/2008/3062/

Hoblitt, R. P.; Walder, J. S.; Driedger, C. L.; Scott, K. M.; Pringle, P. T.; Vallance, J. W., 1998. "Volcano Hazards from Mount Rainier, Washington." revised 1998: U.S. Geological Survey Open-File Report 98-428, 11 p., 2 plates. http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Hazards/

Pringle, Patrick T., 2008. "Roadside Geology of Mount Rainier National Park and Vicinity." Washington Division of Geology and Earth Resources Information Circular 107, 190 p. http://www.centralia.edu/academics/earthscience/pringle/rainier_geology_guide_pat_pringle.htm

Scott, Kevin M.; Vallance, James W., 1995. "Debris Flow, Debris Avalanche, and Flood Hazards at and Downstream from Mount Rainier, Washington." U.S. Geological Survey Hydrologic Investigations Atlas HA-729, 2 sheets, scale 1:100,000, with 9 p. text. http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Hazards/HA-729/framework.html

Scott, K. M.; Vallance, J. W.; Pringle, P. T., 1995. "Sedimentology, Behavior, and Hazards of Debris Flows at Mount Rainier, Washington." U.S. Geological Survey Professional Paper 1547, 56 p., 1 plate. http://pubs.er.usgs.gov/usgspubs/pp/pp1547

Sisson, T. W.; Vallance, J. W., 2008. "Frequent Eruptions of Mount Rainier over the Last ~2,600 Years." Bulletin of Volcanology online, DOI 10.1007/s00445-008-0245-7, [24 p.].

Vallance, James W.; Scott, Kevin M., 1997. "The Osceola Mudflow from Mount Rainier--Sedimentology and Hazard Implications of a Huge Clay-rich Debris Flow." Geological Society of America Bulletin, v. 109, no. 2, p. 143-163.

Zehfuss, Paul H., 2005. "Distal Records of Sandy Holocene Lahars from Mount Rainier, Washington." University of Washington Doctor of Philosophy thesis, 160 p.

Zehfuss, Paul H.; Atwater, Brian F.; Vallance, James W.; Brenniman, Henry; Brown, Thomas A., 2003. "Holocene Lahars and their By-products along the Historical Path of the White River between Mount Rainier and Seattle." In Swanson, Terry W., editor, Western Cordillera and adjacent areas: Geological Society of America Field Guide 4, p. 209-223. http://fieldguides.gsapubs.org/content/by/year

Web links

USGS links to videos about volcanic hazards

Map showing volcanic hazards zones associated with Mount Rainier

Mount Rainier volcanic hazards plan

U.S. Geodynamics Committee, 1994, Mount Rainier: Active Cascade volcano; Research strategies for mitigating risk from a high, snow-clad volcano in a populous region: National Academy Press, 114 p. [accessed web version http://www.nap.edu/catalog.php?record_id=4546]

http://www.kingcounty.gov/operations/GIS/Maps/iMAP.aspx The iMAP gives access to all kinds of hazard and resource maps, including flooding (inundation) and channel migration.

http://www.kingcounty.gov/environment/waterandland/flooding/warning-system.aspx This King County web site includes a tab that gets you directly to flood maps for the different major King County river basins.

http://riverhistory.ess.washington.edu/ The University of Washington River History website includes many valuable links to old maps etc.