ESS 125

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ESS 125 Volcanoes LAB

• Volcano Scenario 6

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Major metropolitan area (city)
10 km
Contour interval 1000 feet
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Numbers indicate locations of volcanic deposits
(see following slides).
10 km
Contour interval 1000 feet
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Volcano Scenario 6 History of Eruptions

• Large eruptions involving multiple hazards
  occurred about 13,000 years ago and about 6,000
  years ago. For the past 2,900 years, only small
  eruptions have happened. The small eruptions
  involved the growth and collapse of lava domes
  with small lahars and pyroclastic flows at about
  2900 and 2000 years ago, and again between
  850-1200 years ago (multiple events).
• In the most recent events, lahars and pyroclastic
  flows have traveled up to 15 km from the vent,
  but most are smaller. Ash from an eruption about
  6,000 years ago can be found 100s of kilometers
  away, and had a total volume beween 10-100 km3.
  Most ash deposits are more localized, closer to
  the volcano.

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View of volcano
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Volcanic deposits (3 different deposits). Middle
layer is about 2 feet thick. Location 1 on map.
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Volcanic deposit. Location 2 on map.
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Volcanic deposit along road at Location 4 on map.
hammer handle in center is about 40 cm long
(about 16 inches)
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Volcanic deposit. Location 3 on map. Largest
block is about 1 foot across.
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Volcanic deposit location 3.
Note cracks radiating from the center of this
block. This indicates a significant difference
in temperature between the block (hot) and
surrounding matrix (cold).
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Volcanic deposit along road at Location 5.
Close-up of this rock (below right).
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Young volcano deposit near summit. Note small
glaciers at summit.
Photo source U.S. Geological Survey