Mt. Rainier

Mt. Rainier (14,411’) An andesitic stratovolcano. Early lavas date to >800,000 years. 5000 years ago, it was 16,000’ high! A massive debris flow removed ~2000’ from the summit and the flows reached Puget Sound, some 30 miles away. And they were 30 meters thick at this point! Mount Rainier is currently listed as a Decade Volcano, or one of the 16 volcanoes with the greatest likelihood of causing great loss of life and property if eruptive activity resumes.

United Nations-sponsored International Decade for Natural Disaster Reduction.

Eruption History As many as 11 Holocene tephra layers have been noted. Most recent activity was through most of the 1800s. Summit crater is still steaming.

Most glaciated peak in the lower 48 26 glaciers totaling ~100 km3

Glaciers + steep slopes can be a bad mix.

Hazards Heat + glaciers = lahars (volcanic mudflows). These can travel in excess of 100 mph! Lahars can form with or without an eruption! According to USGS, about 150,000 people live on top of old lahar deposits of Rainier. 3 large lahars in last 5000 years. One event added 460 km2 of new real estate in Puget Sound! During an eruption, also expect pyroclastic flows, tephra, and lava.

Mt. St. Helens 1980 eruption before after Rainier poses a far greater threat – much more ice and many more people living close by.

Other hazards: Tephra Large tephra (>10 cm) does not travel far from the vent. can cause death on impact and are hot enough to start fires Small tephra (< few cm) travel much farther These cause more destruction given the widespread distribution Block sunlight, restrict visibility, create lightning, short out power lines, kill crops, cause respiratory problems, down airplanes, etc.

But there are even more hazardous volcanoes El Misti, Peru 19,100’

Arequipa, a city of 2 million at the base of several 6000 m volcanoes, including Misti

Earthquakes every few decades; send enormous avalanches downslope. Mt. Huascaran, Peru 22,000’ Earthquakes every few decades; send enormous avalanches downslope.

Today’s Assignment: Assess the hazards of an eruption of Mt. Rainier. Data: WA counties and state: Polygon DEM of relevant counties: Raster Lahars: Polygon WA Rivers: Polyline Mt Rainier summit: Point Population data (cities): Point Flow Area Feature to create Tephra Feature to create

Steps: Import and organize the files. b. Mosaic the individual files into a single DEM. c. Select only rivers that have headwaters on Mt. Rainier, and then build a new shapefile with these rivers. d. Specify hazard zones for both tephra fall and lahar flows. Select the towns and cities that would be affected by these hazards. e. Calculate the area affected by lahars and tephra fall and compare these estimates to those of the USGS. f. Calculate the total population that would be affected by a volcanic eruption at Mt. Rainier.

New GIS skills: Explore and convert .e00 files Mosaic raster data Calculate aspect of DEM Multi-ring buffer operations Statistical operations to determine # people effected by lahars and tephra fallout from different size eruptions.