Geologic disasters

Notes: Earthquakes Earthquakes occur at faults Seismic waves - waves of energy released during an earthquake Focus - the place under Earth’s surface where an earthquake occurs Epicenter - the point on Earth’s surface directly above the focus

Earthquake in Haiti http://app.discoveryeducation.com/player/view/as setGuid/5565D0F6-1090-4775-8F42- 903D8848C735

Notes: Volcanoes A volcano is any opening in Earth’s crust through which magma has reached Earth’s surface. Vent - an opening at the surface of Earth through which volcanic material passes.

Where do volcanoes occur? 1) Most land volcanoes occur at convergent plate boundaries. 75% of the active volcanoes on Earth are located in an area known as the Ring of Fire. The Ring of Fire is located along the edges of the Pacific ocean, where oceanic tectonic plates are colliding with continental plates.

Where do volcanoes occur? 2) Underwater volcanoes occur at divergent plate boundaries. As plates move apart at divergent boundaries, magma rises to fill the gap. This magma creates the volcanic mountains that form ocean ridges. Iceland is a volcanic island on the Mid-Atlantic ridge that is growing outward in opposite directions.

Where do volcanoes occur? 3) Volcanoes occur at hot spots in the middle of plates. Mantle plumes are mushroom shaped trails of hot rock that rise from deep inside the mantle, melt as they rise, and erupt from volcanoes at hot spots at the surface. The plumes remain in the same place as the tectonic plate moves, creating a trail of volcanoes. The Hawaiian Islands are an example of this type of volcanic activity.

Mount Vesuvius http://app.discoveryeducation.com/player/view/as setGuid/1765AC70-A204-4B9F-9369- 985F6B0E2E29

Tsunamis Tsunamis are giant ocean waves caused by underwater earthquakes and volcanic eruptions

Tsunami in Japan http://app.discoveryeducation.com/player/view/as setGuid/3E91FF7F-1058-4217-B010- AFB68A8DEBE3