Volcanoes Edited from original. Author Brent Swartz

What are volcanoes? A volcano is an opening in Earth that erupts gases, ash, and lava.

How do volcanoes form? Magma is less dense than the rock around it, so it is forced toward the surface Vent: Opening in the Earth’s surface through which a volcanic eruption takes place Crater: The steep-walled depression around a volcano’s vent at the summit of a volcano

Where do volcanoes occur? A. Divergent Plate Boundaries Iceland Mid-Atlantic Ridge

Where do volcanoes occur?

Where do volcanoes occur? B. Convergent Plate Boundaries Oceanic Plate slides beneath Continental Plate Example: Andes mountains in South America and Cascade mountains in USA Erupt more violently Oceanic Plate slides beneath Oceanic Plate Example: Japan – forms Island Arcs

Where do volcanoes occur?

Where do volcanoes occur?

Where do volcanoes occur?

Where do volcanoes occur?

Where do volcanoes occur?

Where do volcanoes occur? C. Hot Spots Areas between Earth’s mantle and core that are unusually hot. Hot rock forces toward the crust where it melts partially to form a hot spot. Example: Hawaiian Islands Pacific Plate moving over a stationary hot spot.

Hot Spot Occurrence

Where do volcanoes occur?

Liquid Hot Magma!!!!

Volcanic Activity Reports http://www.volcano.si.edu/reports/usgs/