Sleeping Mountain Scenario

This material was originally created for Starting Point:Introductory Geology
and is replicated here as part of the SERC Pedagogic Service.

Original Author: Janice Cooper.
Posted with the permission of Glenn Jaecks, (University of California Davis Geology Department )

Introduction | Format for Discussion | The Reality of the Threat at Mammoth | Web Sites | Paper Assignment


In keeping with the explosive nature of today's topic, we are going to inject a little drama into our discussion, and a little fantasy.

You were born and raised in a little mountain community on the east slope of the Sierra Nevada. This town stayed small because economic opportunities were sparse once the Gold Rush was over.For years, you and your neighbors have scraped along by selling a few Christmas trees in winter and driving logging trucks in summer. However, when Caltrans improved the State highway systema few years ago and old 395 became a much faster 4-lane, the littletown suddenly became accessible from the Los Angeles area, at least for a weekend trip. And just as suddenly, all the snow and steep terrain that had been such a nuisance to daily life for years began to look like money: ski money! Some of your neighbors have gone into partnership to finance the construction of skilifts and renovate some old barns to make instant traditional ski chalets. Others are planning to get rich on the businessesthat spring up around a ski resort: ski-wear shops, bars, restaurants, bars, service stations, bars, and souvenir shops. Real estate investors want to build condos. Others are thinking about summer businesses and plan to open a rollerblade rental and a mountain-bike shop. The community is attracting new residents for the first time in decades: merchants, sporting goods dealers, construction workers, retirees, teachers, and artists. The value of your propertyis going up weekly, with no end in sight. You might even be able to replace the ol' pickup next year, or at least get a new gun-rack!

BUT now a group of Government seismologists and volcanologists has surveyed your area, and they have just made a devastatingannouncement: Mastodon Mountain, the hub of your proposed ski slopes, is a volcano that shows signs of an imminent eruption!

The announcement shocks the entire community. Reactions vary widely. Opinions form quickly and polarize the denizens. Some say BUILD ANYWAY AND LIVE WITH THE RISK, others say SHUT DOWN COMPLETELY AND PREPARE FOR THE WORST.

State officials have called for a Town Meeting to make an inquiryabout the commercial development of the area in view of the geologic hazard. All residents are invited to voice their opinions and recommendations at the Town Meeting. What should be done? Buildor not build? Who should pay for all the extra expenses associated with feasibility studies, environmental impact reports, etc?

Format for Discussion

This is a Town Meeting about the situation, moderated by the State official (your TA). The official is here to listen to theviews of the people, even though it is not quite clear what the official will do about the problem. Rumor has it that the official is very close to Governor Davis, so any action by the State will likely be based on the way the meeting goes.

You will play the role of one of these persons (which may be assigned to you randomly by your TA, so be prepared!) and will put in your two cents worth at the Town Meeting:

  1. The Geologist. A person knowledgeable about the devastating effects of volcanic eruptions, particularly those like Mount Saint Helens, with explosions, hot ash falls, mud flows caused by rapid snow-melts. Make recommendations to mitigate the effects of an eruption.
  2. The Ski Resort Owner. An investor who is faced with financial ruin if the resort under construction must be abandoned. Make arguments that make the danger sound less threatening. Emphasize potential for prosperity in community.
  3. The Fire Chief. The person responsible for coordinating all emergency services to the community. What will you need in case of an eruption? More ambulances and fire trucks? More police? More paramedics? A helicopter? And where are you going to get them from? (Who will pay for them?)
  4. The Big Land Developer. This real estate tycoon has bought land with a potential of making big profits on condo sales. But development may not be possible if the land is rezoned to a red-zone for family dwellings. In any case, new building permits will be more expensive because the city will have to be able to pay for additional emergency services suggested by the Fire Chief.
  5. The Local Environmentalist. A conservationist and tree-lover who did not want the ski resort in the first place.
  6. The Insurance Person. This person is the underwriter for all the homeowner's policies and business policies in town, but now the insurance company is in jeopardy if an eruption happens. How high must the rates be increased to cover a possible disaster?
  7. The Regional Caltrans Director. This transportation planner expects that roads must be widened and additional escape roads will be necessary to accommodate heavy traffic volume in case of emergency evacuation.
  8. The Unemployed Resident. Oh boy! Jobs! First, things looked good, and now they look bad again.
  9. The Resident with Five Kids. Parents face not only the threat of a natural disaster that would endanger themselves, their kids, and their house, but also the burden of paying for bills in preparation for eruption, even if it never happens: re-siting schools, roads, hospitals, emergency equipment. Should they leave their hometown? Vote against any new taxes and cross their fingers? Do they believe the geologists anyway? (Geologists cannot predict actual dates and times.)
  10. The State Official from the Office of Emergency Preparedness. This person is just interested in the safety of the citizens; the cost to individuals or to the community does not concern him or her. The official will lay out steps the State proposes to accomplish, even though it is not clear whether the State will pay for it or merely order the town to do it. The official's priority is for human life, because the measure of any disaster is the number of dead. The only way this official can be fired is by letting a lot of people get killed.
  11. The Mayor. He or she has to look like a leader, yet there is zero chance of re-election by promoting some action that will cost too much tax money on the one hand or seems deliberately negligent on the other. The town faces potential bonanza and potential doom. What is the Mayor going to recommend to the City Council?
  12. The Local Congressman. This person is between a rock and a hard place. It is politically impossible to get relief money before a disaster, only after it. She or he has heard both sides of the issue (the few developers as well as the many parents), but must make a decision that represents the best interest of all the residents (voters!). The Congressman has to say something. She/he cannot just sit there like a stuffed penguin.
  13. The Investigative Reporter from the Local TV Station. The TV journalist is looking for dirty dealings, especially by the big developers and investors who may try to sidestep the legal hassles. Jackpot! Speak up with nasty questions, if you can! This may be your chance to write a hard-hitting story that will get you national attention and maybe five minutes on the Today show!

The Reality of the Threat at Mammoth

In case you are wondering whether this is just something we dreamed up, it's not. It is based on real events at Mammoth, California. In August 1995, the United States Geological Survey (USGS) reported on a five-year study of worrying events in and around the Mammoth area. They reported that volcanic gas (carbon dioxide, mainly) was seeping out of the ground around Mammoth in sufficient quantities to damage tree roots and kill acres of trees in at least fourareas on Mammoth mountain. Seismographs were recording large numbers of small earthquakes over an area of several square miles. "It's a very restless volcanic system," said David Hill of theUSGS, who had been monitoring seismic activity at Mammoth for many years.

Mammoth Mountain first erupted violently 200,000 years ago, and large steam explosions, caused when hot magma boils groundwater near the surface, have left deep pits as records of eruptions as recent as 200 to 500 years ago. Mammoth Mountain itself ison the western edge of Long Valley Caldera, the last vestige of a huge volcano that blew its top and rained ash throughout the far West more than 700,000 years ago.

In 1980, three strong earthquakes with magnitudes as high as M5.7 and M6 shook the Mammoth ski resort badly. Even today fumaroles in the region vent hot steam into the air.

Modest seismic activity at Mammoth has been steady since 1989,but the emission of tree-killing carbon dioxide, first noticedin 1990, shows that much more powerful activity is going on at greater depths. The USGS found that carbon dioxide was very concentratedin some areas. In the winter of 1990 a forest ranger was nearly asphyxiated by gas that had seeped into a snow-covered cabin. The Forest Service closed Horseshoe Lake campground because buildings there were considered hazardous.

The 1995 survey found that trees had been killed in four separate areas covering 75 acres on Mammoth mountain. The USGS calculatedthat more than 1200 tons of carbon dioxide were reaching the surface around the summit every day. Many other volcanoes around the worldthat have erupted violently in the past, such as Mount Etna in Sicily, and Santorini in the Mediterranean near Crete, are also known for their continuing emissions of carbon dioxide.

But unlike those legendary mountains, Mammoth (for now, atleast) is discharging neither heat nor acid gases and is showing no evidence of deformation or strong seismicity. Professor Stanley Williams of Arizona State University said, "The gases are waving flags at scientists, and more importantly, at the people who live or work near the activity. An active magma source is sending out signals... we must give it more attention."

In November and December 1997, Mammoth had an unusually long and intense set ("swarm") of small earthquakes. TheUSGS came very close to calling a volcanic alert. They would have done so if there had been an M5 earthquake, but the largest was M4.8. Certainly the USGS is watching Mammoth with more than normal interest!

Web Sites

Now read some or all of these Web pages to prepare for the discussion:

If you read just a few, read these:

Related sites (not required, but they have good information for the discussion):

Last modified October 1, 2001 by Richard Cowen.

Writing Assignment

Due in your discussion section this week.

Write a three-page account (750 words or so, plus any illustrations you choose to make your presentation clearer) of the methods that are being used to monitor the activity at any volcano of your choice.

Obviously you don't choose a volcano that is not being monitored. You might look first at volcanoes along the Cascade Range, such as Baker, Hood, St. Helens, but the choice is yours: Vesuvius? Popocatepetl? Kilauea? If you think that the monitoring is not extensive enough, suggest what might be added to the system (realizing that you the taxpayer are going to help pay for it!).

There's a warning there that we will repeat here: DO NOT lift material from your sources: that is PLAGIARISM and you get a zero. Use your own words!