Geology 204

Natural Disasters

Homework Assignment III. Volcanological Exercises

1. Imagine that in your work as an insurance company executive you have been reassigned to head up the Tacoma, Washington office of your company, Denyallclaims Insurance Co.  Although Tacoma is located about 50 miles from the volcanic mountain, Mount Rainier, other executives in Denyallclaims have reassured you that the volcano has not erupted for a long time, and there is no risk associated with the volcano if you choose to live in Tacoma or its beautiful mountainous suburbs.  You decide to check things out for yourself, and log on to the internet to search for volcanic hazards associated with Mt. Rainier, Washington.  The following are questions you want answered, and which you should answer for this assignment.

1. When was the last time Mt. Rainier had an eruption? (0.5 point)
2. Are there any types of volcanic hazards associated with Mt. Rainier that could affect you in the future if you were living in the area of Tacoma or its suburbs?  If so, what types of hazards have affected the Tacoma area in the past? (2 points)
3. Considering that the summit area of Mt. Rainier is covered to a large extent by glacial ice, would residents of the Tacoma area be threatened in any way by a small eruption from the volcano that only sent a few lava flows down the flanks, none reaching more than 1 km from the summit?  If so, why, and if not, why not? (2 points)
4. Give the URL(s) where you found your information. (0.5 point)

2. Go to the Volcano World site, run by the University of North Dakota: http://volcano.und.nodak.edu/.   On this site is a section called "Ask a Volcanologists" where people have written in asking some pretty basic questions about volcanoes.  Some the questions that have been asked are probably questions that you have been thinking about during our discussion of volcanoes.  The "Ask a Volcanologist" section has been discontinued, but  these questions have already been answered by the Volcano World scientists, and are still available on the web site. Use this section to find the answers to the following questions.  You might also learn some other things as well by reading through some of the other questions.
   
   1. How long does it take lava to cool so you can walk on it? (1 point)
   2. For volcanic eruptions that have killed more than 500 people throughout recorded history, give the name of the volcano, the year it erupted with deadly consequences, and the major cause of death.  What two or three types of activity appear to cause the most deaths? (2 points)
   3. How could one predict if a volcano will erupt pyroclastic material or lava flows in its next eruption? (1 point)
   4. What is the Volcanic Explosivity Index (VEI)? (1 point)
   5. How many volcanoes are there in the world (with eruptions within the past 10,000 years)? (1 point)

3. Go the following web site: http://www.agiweb.org/geotimes/may00/featurestory.html read the article entitled: "Mount St. Helens 20 Years Later: What we have learned".  Then answer the following questions.

1. Give a summary of the sequence of events that occurred at Mount St. Helens beginning at about 8:32 AM on May 18, 1980 and ending on May 19. (2 points)
2. Which one of these events was the main cause of human fatalities? (0.5 point)
3. How many people died as the result of the eruption? (0.5 point)
4. What three important lessons were learned form the eruption (summarize in your own words? (2 points)
5. What is probably the most far-reaching scientific finding from the eruption?  Why is this important? (1 point)
6. Were scientists aware of the fact that Mount St. Helens could have a devastating eruption in the years prior to the 1980 event? (0.5 point)
7. Where volcanic hazards studies and programs well-funded prior to the Mount St. Helens event and did anything change after the event? (1 point)
8. What was the approximate economic loss due to the 1980 eruption? (0.5 point)
9. What factor(s) most strongly influence awareness of and increased funding levels for volcanic hazards studies (and natural hazards studies in general)? (1 point)

4. Some volcanic eruptions have occurred within the last several million years that are larger and more destructive than anything a human being has ever witnessed, or at least lived to write about.  These volcanoes erupt  between 100  and 1000 km³ of magma, mostly in the form of Plinian tephra falls and pyroclastic flows (ignimbrites) and result in the formation of large collapsed areas, called calderas.  Three of these volcanic centers have erupted within what is now the United States in the last 1.2 million years.  These are - Long Valley Caldera, Yellowstone Caldera, and Valles Caldera.  This exercise asks you to learn about one of these large rhyolitic eruptive centers, Long Valley Caldera.  A good starting point is located at http://quake.wr.usgs.gov/VOLCANOES/LongValley/index.html

1. Where is Long Valley Caldera located? (0.5 point)
2. When did Long Valley Caldera form? (0.5 point)
3. How much magma was erupted from the Long Valley system during the Caldera forming eruption? (0.5 point)
4. How far east is ash from this eruption still found today? (1 point)
5. Where and when was the most recent volcanic activity in the Long Valley area? (0.5 point)
6. Is there any indication that the Long Valley magma system is still active? If so, what evidence is there that the system is still active and that volcanic activity is likely to continue into the near future? (2 points)

5. Use the internet to answer the following questions:
   
   1. What possible volcanic event could occur in the Canary Islands (off the northwest coast of Africa) that could have a disastrous effect on the east coast of the United States?  (Try the key words - Canary  - Islands  - disaster) Describe the possible event and the possible effects it would have on the United States. (2 points)
   2. How much warning would U.S. east coast cities have to prepare for the event if it occurred? (1 point)
   3. Who are the scientists that have brought this matter to the attention of the world? (0.5 point)
   4. Give the internet address (URL) of the site where you found the information to answer these questions. (0.5 point)