Faults, Earthquake waves, Finding the Epicenter, Volcanoes, and Hot Spots

Strike-Slip FaultNormalReverse Faults are fractures (breaks) in the Earth’s crust. When the rock layers along faults slip, earthquakes occur.

 A famous strike-slip fault that lies on a transform plate boundary is the San Andreas Fault.  Slippage along the fault can cause fences and roads to be split apart.

What does the picture to the right show? How is this pattern of lines made? Why do you think some lines go higher/taller than others? Earthquakes

What does the picture to the right show? The picture to the right is a seismogram - a image showing the arrival of an earthquake to a seismograph station Earthquakes

How is this pattern of lines made? This pattern is made by a seismograph machine. Earthquakes

Why do you think some lines go higher/taller than others? The height of the line depends on the strength (intensity) of the movement caused by the earthquake Earthquakes

 An earthquake is the result of a sudden release of stored energy in the Earth's crust that creates seismic waves.  When two plates slip past one another or collide, different kinds of stress result.

The Richter Scale: Measures how strong the earthquake is – how much energy is released at the fault Each number increases by a power of 30

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The Mercalli Scale Measures the damage caused by the earthquake. Scale is used by insurance companies Damage looks less the farther you move away from the epicenter

 Focus—point below Earth’s surface where earthquake originates  Epicenter—point on Earth’s surface directly above focus  Fault—break or fracture of rock at Earth’s surface where movement can occur  Stress—force put upon rock

 There are 3 different types ◦ P waves ◦ S waves ◦ Surface waves  They have helped scientists learn more about the interior of the Earth!  atch?v=yOGoKCK17a4 atch?v=yOGoKCK17a4

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 P-waves— compression waves ◦ Move through solids and liquids ◦ Fastest waves

 P waves (Primary waves) travel fast and arrive at seismic stations first.  P waves can travel through solids, liquids, and gas.  When a P waves moves from a solid (rock) to liquid (outer core), it slows down.  P waves but are usually more intense.

 S-waves ◦ Move perpendicular to wave direction ◦ Do not move through liquid ◦ Slower than P- waves

 L-Waves (Surface Waves) ◦ Are the slowest moving waves ◦ Cause the surface to rise and fall (roll) like ocean waves ◦ Also cause the most damage!

Reading a Seismogram – Finding the Difference Between P and S wave Arrival Times 0312

Calculating the Difference in P and S Wave Arrival Times when told distance 1.Determine the distance from the epicenter of the Earthquake to the seismograph station 2.Using the distance (700 miles) determine when the P-wave and S-wave arrived: a.P-wave: 700 miles = 2.5 minutes b.S-wave: 700 miles = 5 minutes 3.Calculate the difference between arrival times: a.S(-wave) - (P-wave) = 5min. – 2.5 min = 2.5 minutes 2.5 minutes after the earthquake occurs its strength can be felt at the seismograph station

 You can calculate the distance from the earthquake epicenter by looking at a seismogram and calculating the time difference between the P and the S wave.  Then you use a time-travel graph to determine the distance from the epicenter.  Next you can draw a circle around the seismograph station using the distance from the epicenter as your radius.  Finally, you can find the point where the circles from 3 seismograph stations intersect and determine the earthquake epicenter.

 The Mercalli Scale rates earthquakes based on the observed effects.

A shield volcano was made from lava (molten rock) only. Shield volcanoes are large, have low angles, and have a gentle, slow, ooze of lava flowing out. They are found at hot spots and volcanoes in ocean crust. The Hawaiian islands are examples of shield volcanoes. close to a volcano footage Axj2ob_JoU&feature=related video/2014/nov/13/hawaii-kilauea- volcano-lava-pahoa-video

Composite volcanoes have steep sides, are large, and made of layers of ash, lava and cinders (pieces of molten rock/ash). Composite volcanoes have sudden, explosive eruptions that produce ash clouds and pyroclastic flows. They are fast and they are dangerous. They occur at subduction zones and plate boundaries. Mount Saint Helens (USA) and Mount Vesuvius (Italy) are examples of composite volcanoes. Pompeii v=AN4ZXcNFZAk buco-volcano-erupts-chile- evacuation

Cinder cone volcanoes have VERY steep sides. They usually form quickly and are made of all cinders. Their eruption is constant. “Spitting” cinders at the top. They are not very dangerous. They form on continental crust. They are like hot spots. They can form anywhere. Paracutin, Mexico has an example of a cinder cone volcano. It appeared one day in a farmers field.

 Cinders are molten rock that is erupted by a volcano.  Mt. Vesuvius erupted in 79 AD, burying buildings and people in volcanic ash. The volcanic ash hardens around a person’s body, making a mold. People visit the ruins and check out casts of people that were buried that day.  Volcanoes have been found on other planets, including Olympus Mons on Mars.

 “Mantle Plumes” Superheated fountains of molten (melted) rock  “Hot Spots” They are the geographic location above a “Mantle Plume” which is usually characterized by volcanic activity. Hot Spots produce a linear series of “Seamounts” and “Volcanic Islands” with the youngest and most active one being over the Mantle Plume.

Distance = rate x timeor Rate =Distance time What was average speed of the Suiko seamount as it moved away from the hot spot located at Kilauea? 4950/41 = 120 km/million years

10 most active volcanoes =related