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Earthquake Preview13 Earthquakes Preview Earthquake Preview13 Explain the geological forces scientists believe cause the tectonic plates to move. Scientists believe convection currents in the mantle are responsible for tectonic plate movement. As the magma is heated in the mantle (asthenosphere) it becomes less dense and rises toward the surface contacting the land above (bottom of the lithosphere). The magma is pushed along the bottom of the lithosphere by more material rising behind it. The magma catches on the lithosphere and pushes on it creating plate movement. As the magma cools it becomes more dense sinking back into the mantle allowing the convection currents to continue again and again. Earthquake Preview13 Reverse Fault Normal Fault Strike-Slip Fault Earthquake Preview13 Name that fault! Earthquake Preview13 Force type? Earthquake Preview13 Name that fault! Earthquake Preview13 Force type? Earthquake Preview13 Name that fault! Earthquake Preview13 Force type? Earthquake Preview13 True False S-waves can travel through solids and liquids. There are four waves that are associated with earthquakes. If the P, S and surface waves arrive almost simultaneously, the seismic recording station is close to the epicenter of the earthquake. By noting the change in the speed and the reflection point of seismic waves, scientists have been able to determine the structure of the Earth's interior. Earthquake Preview13 True False P-waves can travel through solids and liquids. Unconsolidated, water-saturated soils or sediments provide good foundation material for buildings and other structures. Earthquakes only happen West of the Rocky Mountains. Earthquake Preview13 Name that wave! Least destructive wave. Earthquake Preview13 Name that wave! Second wave to reach you in an earthquake. Earthquake Preview13 Name that wave! Earthquake Preview13 Name that wave! Earthquake Preview13 Earthquake Preview13 Most earthquakes occur along ____. A. volcanoes B. faults C. rivers Seismic waves move outward from the ___ which is usually deep underground. A. epicenter B. focus C. city What are the smaller magnitude quakes that follow a major earthquake? A. exoshocks B. epishocks C. aftershocks At least ___seismograph stations are needed to locate the epicenter of an earthquake. A.2 B.3 C.4 S-waves do not travel through the outer core because it is __. A. a liquid B. a solid C. plastic-like Earthquake Preview13 Earthquake Preview13 Most of the destruction during an earthquake is caused by (surface waves, secondary waves). Seismologists use the (seismograph, Richter Scale) to compare the magnitude of earthquakes. The slowest seismic waves are (primary waves, surface waves). Primary waves arrive at a seismograph station (first, second). Scientists use the triangulation method to locate an earthquake's (epicenter, focus). When the buildup of stress in Earth's crust is so great that rocks reach their (elastic limit, tectonic force), an earthquake occurs. Earthquake Preview13 Write the correct letter in front of the proper fault name. Strike-slip fault Normal fault Reverse fault Earthquake Preview13 Normal Fault Reverse Fault Rocks above the fault surface move downward in relation to rocks below the fault surface. This kind of fault occurs at divergent plate boundaries. Tension pulls rocks apart. The Himalaya Mountains contain many of these faults. Rocks above the fault surface are forced up and over the rocks below the fault surface. This kind of fault occurs at convergent plate boundaries. Compression pushes rocks in. The San Andreas Fault is an example of this kind of fault. Strike-slip Fault Rocks on either side of the fault boundary move past each other without much upward or downward movement. Shearing forces push rocks from different, but not opposite, directions. This kind of fault occurs at transform fault boundaries. Earthquake Preview13 Earthquakes An earthquake is any violent shaking or rapid motion of the earth's surface. Pick a number and name the earthquake feature: Epicenter - Location on surface above Focus Focus - Location along fault where earthquake occurs 3 1 2 Fault - Large break in Earths Crust where movement occurs Earthquake Preview13 Earthquake Preview13 Earthquake Waves P-Waves Travel by Pushing and Pulling the earth. Very Fast S-Waves Travel by moving earth side to side Slower than P-waves shear wave Causes most damage First wave to arrive 2nd wave to arrive Pwaves can travel through the core Swaves CANNOT travel through the CORE Earthquake Preview13 Determine Distance to Epicenter 1. Subtract Travel Times to find the difference in Travel Times. 2. Find the point on the table where the waves are separated by that amount of time. 3. Follow that point down to the distance. 4. That is the distance to the epicenter P-wave travel time time difference S-wave travel time Distance to the Epicenter Earthquake Preview13 Earthquake Shadow Zone: Area on earth that does not recieve any waves from a PARTICULAR earthquake.