1. Volcanoes

2. Volcanoes – Plate Tectonics
Volcanic eruptions are causing earthquakes – especially on the sea floor.
Areas of intense earthquake activity:
Ring of Fire, Mid-Atlantic Ridge, and Hawaii and other hot spots.
Mt. St. Helen’s (a volcano in Washington state) occurred because of convergent plate movement – in a subduction zone.
Divergent plate movement – plates moving apart, creates new sea floor.

3. What causes volcanoes to erupt?
Volcanic Eruptions
What causes volcanoes to erupt?
Water and carbon dioxide are dissolved in the magma in the magma chamber in the volcano.
When the pressure goes down, the gases (water and carbon dioxide) do not want to be dissolved so they form bubbles. (Think about a bottle of soda)

4. DRAW PICTURE ON THE BOARD.
Small bubbles combine to form bigger bubbles, which move toward the surface at a high velocity.
200 to 900 miles per hour.
Eruptions are driven by:
Dissolved gases
The formation of bubbles
The bubble/magma mixture rising to the surface
DRAW PICTURE ON THE BOARD.

5. Volcanoes - Ash
Volcanic ash is NOT smoke. It is a ground up mixture of rock and glass.
Ash causes damage on the ground and in the sky.
Ash can get sucked into engines of planes causing damage and possibly engine failure.
Volcanic ash forms when the force of the eruption pulverizes the rock.

6. Bubbles in ash are the trapped gases that are driving the eruption
Bubbles in ash are the trapped gases that are driving the eruption. The bubbles are caused by frozen liquid hot magma.