Volcano Slope Lab
Shield volcanoes are formed by successive flows of basaltic lava. When these lavas erupt the spill over earlier flows, cool and harden. Since basaltic lavas are of relatively low viscosity, they can flow easily down surfaces with slopes of less than 11 degrees.
Stratovolcanoes create rhyolitic lavas. Their eruptions are often explosive. Due to high viscosity of this rhyolitic lava, lavas need steeper slopes to flow greater than 11 degrees.
Objectives
Determine the slope of a volcano
Identify a volcano as either shield or stratovolcano.
Mt. St. Helens
1. Mt. St. Helens’ base is at an elevation of 4,000’ and a peak of 9,677’
What is its change in elevation?
2. Mt. St. Helens has a distance from its center to its base of about 3 miles (5,280 feet = 1 mile). How many feet is this?
3. To find the slope of a volcano; divide the change in elevation by the distance from center to base (rise / run).
4. Use a tangent table to estimate the slope (in degrees) of Mt. St. Helens.
Mauna Loa
1. Mauna Loa’s base is at an elevation of 5,000’ and a peak of 13,300’
What is its change in elevation?
2. Mauna Loa has a distance from its center to its base of about 16 miles (5,280 feet = 1 mile). How many feet is this?
3. To find the slope of a volcano; divide the change in elevation by the distance from center to base (rise / run).
4. Use a tangent table to estimate the slope (in degrees) of Mauna Loa..
Analysis
1. Based on your results, which volcano is a stratovolcano?
2. Based on your results, which volcano is a shield volcano?
3. What type of lava would you expect at
Mt. St. Helens-
Mauna Loa-
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Tags: formed by, volcanoes, formed, successive, volcano, shield, slope