FDSCI 201 Hybrid: Volcanic Hazards Assignment 60 Points



Lesson 4 Guided Lab—Volcanoes

Instructions: Find the answers to the questions and write them on the lab. You will need to use the Internet to answer most of the questions.

PART I Volcanic Hazards in the Northwest U.S.

You have been offered a job in Tacoma Washington. You are taking a tour of the area on a rainy afternoon. The rain clouds lift and you see a breath-taking cone-shaped mountain – Mt. Rainier. Your soon-to-be manager excitedly tells you that it is a great place to hike, camp, fish, ski, and mountain bike -- and it is located only 50 miles away. Sweet!

The manager says that Mt. Rainier is a volcano, but assures you, “it has not erupted for a long time and there is no risk associated with it.” In fact, she has offered to sell you her home in nearby Orting, WA for what seems like a good price.

You decide to check things out for yourself, and go to the Internet to search for hazards associated with Mt. Rainier, Washington. Here are questions you (and your professor) want answered. Use the USGS Mount Rainier Fact Sheet found in I-Learn with this worksheet and this webpage:

According to the USGS, when did Mt. Rainier last have a significant eruption? [pic]

If you look around at other sources you will find that there were reports of eruptions in the 19th century (1800s), but as experts have looked closely at these stories they seem to be coming to the conclusion that nothing that should really be called an eruption happened that recently. What people observed in the 19th century was most likely just steam venting, but even if there was some ash erupted, it was so small an amount that it left no evidence that survives into the 21st century. The fact sheet is a PDF file, if you don’t have Adobe Acrobat Reader on your computer, download it for free at .

A hazards map for the area around Mount Rainier is also found on the USGS Mount Rainier Fact Sheet. From the key for the map, what primary volcanic hazard exists in Orting, Washington where the manager has offered to sell the house? [pic]

Describe thoroughly what a lahar is, how one is formed, and why they are dangerous. [pic]

How often, according to the map key, do lahar events occur at Rainier (i.e. what is the shortest recurrence interval)? [pic]

The summit area of Mt. Rainier is covered to a large extent by glacial ice. A small eruption of lava flows that reach less than 1 km from the summit could melt the glaciers ice. Briefly explain how this could cause a lahar that might threaten Orting.

[pic]

Lahars typically travel 40 – 50 mph.

Using Google Earth and the measuring tool, approximate the distance between the top of Mt. Rainier and Orting, along the river, in miles.

[pic]

About how much time is there to evacuate Orting after a lahar starts down Mt. Rainier (in hours, use decimals)?

[pic]

Look at Orting on Google Earth. How many rivers border the town of Orting (make sure you have the boundary of Orting visible)?

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How many bridges are there across the rivers where they border Orting (don’t go up or downstream beyond the borders of Orting)?

[pic]

How would you evacuate your family away from the volcano and the rivers if you lived there? Describe a complete and practical plan. Remember, you and your family members are away from home for much of many days a week.

[pic]

What is your acceptable risk for volcanic hazards? Would you live in Orting? Why or why not?

[pic]

[pic]

Topographic relief of Mt. Rainier and Orting Washington area.

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[pic]

Mt. Rainier as seen from Tacoma, Washington.

(Photo courtesy of Tacoma Visitors Bureau)

miles

hour

Puyallup

River

Carbon River

Orting

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