Lava Flows on Plastic Three-dimensional Maps
This model is easy to demonstrate and very useful in relating hazards associated with lava flows (or mud flows). However, this model costs more and requires you to order a plastic three-dimensional map.You will need:
- raised relief map
- ($20 plus shipping from Hubbard Scientific, 800-523-5485)
- Omni Resources (1-800-742-2677) sells raised relief maps of Mt. Rainier (12 x 18", $8.95), Yellowstone (18x25", $10.95), Naples (Vesuvius)(2x3', $69.95), Catania (Mt. Etna)(2x3', $69.95), and Reunion (27x23", $49.95).
- molasses
- a straw
Step 1. The Map
A raised relief map shows shape and size of a volcano without any
distortion. This photo shows a raised relief map for the island of
Hawaii. The rifts zones of Kilauea and Mauna Loa
volcanoes are highlighted with
silver tape. In Hawaii eruptions originate at the summit or along the
rift zones of the volcano. Purchase (or make) a relief map of a volcano
that is of interest to you (perhaps a well known volcano or one near your
home or school.
Step 2. The Lava
Molasses is a good substitute for lava. It is more viscous (stickier) than water and will move slowly down the map.
Step 3. The Eruption
Place the map on a table or on the floor. Stand or sit next to it.
Place the straw in the molasses and put your thumb over the top of the
straw so the molasses stays in the straw. Move the straw over to the
relief map. Take your thumb off the top of the straw so the molasses pours
out. Gravity will pull the molasses down slope just like it pulls lava
down the slope of the volcano.
Step 4. Factors that Influence Lava Flows
This simple model can demonstrate the factors that influence where lava
will flow. For example, start your eruptions at the summit or high or
low on a rift zone. Vary the amount of lava erupted (one straw full
versus several straws). Vary the duration of the eruption (empty the
straw at intervals of 5 seconds). Vary the slope of the volcano (lava
moves faster on steep slopes). Can you predict what eruption conditions
are needed to reach a specific location on your map?
5. Reality
Compare you lava flows and relief map to known historic lava flows for
the volcano you are interested it. The U.S. Geological Survey's Cascade
Volcano Observatory
provides
detailed histories on each Cascade volcano. Do the flows on your map
resemble any of the known historic lava flows? If they do what were the
conditions during that eruption?
6. Alternatives
Not all volcanoes erupt fluid lava flows that travel far from the vent. Some volcanoes produce fluid mudflows that do travel far down the volcano. This demonstration could be easily modified to show areas that are susceptible to mudflows on a volcano.
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