Presentation on theme: "By Andrea Snell Revised by GBrenneman"— Presentation transcript:
1By Andrea Snell Revised by GBrenneman S and How they shape the EarthBy Andrea SnellRevised by GBrenneman
2Earthquakes are a sudden movement of Earth’s crust that releases energy. CA quake The crust of the Earth is constantly moving, but are usually slow – until a major earthquake takes place.About 95% of all earthquakes occur at or near the edge of moving plates. Worldwide Earthquake LocatorThey occur along cracks in the Earth’s crust called faults. Faults are associated with, or form, the boundaries between Earth’s tectonic plates.Earthquakes do not occur randomly.
4Types of stress in the Earth’s crust lead to fault lines.
5Types of FaultsStrike-slip faultsNormal FaultsReverse Faults
6Modeling Fault TypesFoam Fault Models and Examples
7Normal Faults animation of normal fault Normal Faults create space. Two pieces of the crust pull apart, spreading the crust apart.
8Reverse Faults animation of reverse fault Reverse faults squeeze the crust and push two blocks of crust on top of one another.Usually these faults are found in the Rocky Mountains andHimalayas and cause mountains to form.
9Strike-slip faults animation of strike-slip fault Indicates rocks are sliding past each other, with little to novertical movement. Both the San Andreas and AnatolianFaults are strike-slip.
10Epicenter and Focus video lecture The epicenter is the point the Earth’s surface, or land, directly above the earthquake focus.The focus is the hypocenter of an earthquake. The vibrating waves travel away from the focus of the earthquake and move in all directions.Earthquakes do not start at the epicenter.
11Earthquake WavesThe energy from an earthquake travels away from the focus in waves.The waves travel in different speeds.There are two types of waves1. Those that travel inside the Earth2. Those that travel only at the surface
12Waves that travel inside the Earth Demo of S waves and P waves Primary Waves, or P Wave, are “push-pull” waves that cause back-and-forth vibrations in the same direction as the wavesmove. The P-Waves are fast-moving.Secondary Waves, or S waves, cause vibrations at right angles to thewaves direction of travel. The S waves are slow-moving.
13Surface Waves Surface waves explanation Surface waves- only travel only at the surface and move slower than P-waves or S-waves.These waves make the ground roll and sway. They can cause a great deal of damage to buildings, roads, and other surface features. pool shakes
14Locating an Earthquake Lab Preview for epicenter lab
15Measuring Earthquakes Earthquakes are recorded by instruments called seismographs. Seismographs record seismic waves. The motion is measured electronically and recorded in a computer. They can measure both S and P waves. The size of the waves is called magnitude.To tell the strength of the earthquake scientists use a Richter Scale. The larger the number on the Richter Scale, the larger the earthquake. You won’t even feel an earthquake if it is below a 3. Today scientists also use the Moment-Magnitude scale.NASA sci fileEach number is 32 times greater than the previous number.4.0 -Would shake your house like a large truck passes by.5.0 – Things might fall off shelves. Walls might crack and windows break.7.0 – Weaker buildings could collapse. Also cracks may occur in streets.8.0 – Buildings and bridges could fall down and large cracks in surface.9.0 and up- Large scale damage and cities flattened.
21Mountain Building mountain building (clip) Fault-Block Mountains: When normal faults uplift a block of rock, a fault-block mountain forms. The Grand Tetons in Wyoming and Idaho are one such example.
22More mountainsFolds are compressions from two plates colliding. The Appalachian Mountains were formed in this way.
23Anticlines and Synclines Anticlines and Synclines can be found in folded mountains. Anticlines, such as the Black Hills in South Dakota, are the folds in the rock that bend upward while synclines, such as the Illinois Basin, are the folds in the rock that bend downward.
24Plateau - a large area of flat land elevated high above sea level How the Grand Canyon Was Formed