Changing Earth Movement in Earth

Questions to Answer How does the movement of tectonic plates affect the Earth’s surface? How does the transfer of energy relate to earthquakes and volcanoes? How do humans prepare and respond to natural events?

Earth’s Interior

I. Earth’s Interior A. Three major layers of the Earth 1.Crust – outermost & thinnest layer Cool and solid rock Divided into continental and oceanic crust 2.Mantle – middle layer Hot and liquid rock, 80% of Earth’s volume 3.Core – center layer of earth Divided into inner and outer core Outer = hot and liquid metal (iron & nickel) Inner = hot and solid metal “ “

Earth’s Interior 1.Continental Crust 2.Oceanic Crust Less dense Thicker, deepest beneath mountains 2.Oceanic Crust Beneath the ocean water More dense Thinner

B. Plate Tectonics 1. Alfred Wegner introduced the idea of Pangaea (noticed coastlines fit together) A large supercontinent 2. Broke apart because of plate tectonics –theory that Earth’s surface is made of large moving plates Moving of Earth’s plates Causes the land to look different on Earth

Plate Tectonics 3. Movement happens because Earth’s makeup a. Lithosphere Crust and rigid upper mantle These are the ‘plates’, 7 large pieces & several small pieces (tectonic plates) b. Asthenosphere Mantle just below the lithosphere Very liquid and slowly flowing

Plate Tectonics

C. Plate Boundaries 1.Any place plates meet and move is known as a fault (crack in Earth) Three Types of Plate Boundaries a. Divergent Boundary Move apart b. Convergent Boundary Move together c. Transform Fault Boundary Move along side (scrape past each other)

2. Divergent Boundary Cause trenches and ridges (mid-oceanic) Forms new crust, magma rises between- Rift valley- most studied- Mid-Atlantic Ridge

3. Convergent Boundary Cause trenches, volcanoes, mountains Subduction occurs More dense oceanic crust slides under less dense continental crust

4. Transform Fault Boundary Cause rocks to crack and break Causes lots of earthquakes

D. Evidence 1. Magnetic rocks in the earth change polarity

Evidence 2. Land shapes 3. Fossils 4. Ancient climates

Tectonic Plates

II. Earthquakes and Volcanoes

A. Earthquakes 1. Shaking or trembling caused by the sudden release of energy 2. Usually associated with faulting or breaking and slipping of rocks a. Occur at boundaries of plates b. Release energy that create seismic waves 3. Continuing adjustment of position results in aftershocks

Movement of Rock

Earthquakes 4. Focus 5. Epicenter The point underground where the rocks start to slip Where the earthquake begins 5. Epicenter Spot on the surface directly above the focus (greatest damage here)

Earthquakes

Earthquakes 6. Types of seismic waves a. P waves (primary waves) Fast moving longitudinal waves First waves we detect b. S waves (secondary waves) Slow moving transverse waves Second waves we detect c. Surface waves Rolling wave ( & ) on the surface of Earth Cause the most destruction, collapse of buildings

Earthquakes P Wave S Wave Surface Wave

Earthquakes 7. Seismology Study of earthquakes Use a seismograph

Earthquakes a. Seismology Three seismographs can tell you the location of the epicenter

Earthquakes 8. Measured using the Richter scale

Earthquakes

B. Volcanoes 1. A vent or hole in the crust 2. How a volcano erupts a. Magma collects in a chamber under the surface b. Pressure builds up as the chamber fills c. Pressure gets so great magma rises to the hole and comes out as lava

Volcanoes

Volcanoes 3. Three types- determined by type of eruption a. Shield b. Composite c. Cinder cone

1. Shield Volcanoes Eruptions are mild and occur frequently Creates buildup of a gently sloping mountain Magma is very runny and long flowing Largest of all volcano types

2. Composite Cone Volcanoes Eruptions alternate between mild and explosive Creates layers of lava, ash, & cinders, with steeper sides Magma is thicker, cause most violent eruptions Tallest of all volcano types

3. Cinder Cone Volcanoes Eruptions are rare, but violent Most of lava and ash builds up around vent –”cone” Magma has lots of gas, causing explosion Smallest and most abundant of all volcano types

C. Where are volcanoes? 1.Occur at convergent plate boundaries Oceanic-Continental plates around the Pacific Ocean “Ring of Fire” = location of 75% of volcanoes

Where are volcanoes? 2. Occur at divergent plate boundaries Oceanic-Oceanic split, allowing mid-oceanic ridge to form

Where are volcanoes? 3. Occur at hot spots In the middle of oceanic plates, magma comes up from hole Form a “trail” of volcanoes as plate moves seamount – volcanoes forming under water Mantle plumes

Mt. St. Helens 1980