Internal Forces Shaping the Earth

Tectonic PlatesMagma is like a

conveyer belt (see right):

Heated magma moves up towards the crust, cools and goes downward.

Riding above this system are tectonic plates.

They are large moving pieces that form the earth’s crust.

FaultsWhen two plates meet,

folding/cracking of the rock can happen.

Sometimes rock is not flexible and will crack under the pressure of plate movement.

This fracture in the earth’s crust is called a fault.

EarthquakesWhat is an earthquake?A violent movement of transitioning plates.

Seismograph: Device used to measure an earthquake.

Focus: Below Ground – Where it Starts

Epicenter: Above Ground – Where we feel it.

Earthquake DamageHaiti – January 2010

Types of Earthquake DamageLandslidesDisplacement of landFires (broken gas

lines)Collapsed buildingsTsunamis (see

right):Can travel from

epicenter at 450 mph.

Can produce waves of 50 to 100 feet – or higher.

VolcanoesMagma, gases and water

from the crust or mantle collect underground.

They eventually pour out of a crack in the earth’s surface.

Magma that reaches the earth’s surface is called lava.

To the right:Mt. St. Helen’s – May 1980

Washington

The Ring of Fire