New version page

NAU GLG 112 - Exam 1 Study Guide

Type: Study Guide
Pages: 10

This preview shows page 1-2-3 out of 10 pages.

View Full Document
View Full Document

End of preview. Want to read all 10 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

GLG 112 1st Edition Exam # 1 Study GuideDifferentiation of the Earth: - during Earth’s formation, everything was very hot and it all melted - the material with the highest density sank toward the center of the Earth - the low density material rose toward the surface - Earth is now layered EARTH’S INTERNAL STRUCTURE Layers based on composition:Core Density: 10.7g/cm3Thickness: 3300kmInner: 1300kmOuter: 2000km Mantle Density: 4.5g/km3Thickness: 3000kmCrust Density: 5.5g/km3 totalOceanic: 2.9g/cm3Continental: 2.8g/cm3Thickness: variable Oceanic: 7km These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Continental: 35kmLayers based on physical properties (Rheological layers): -inner core =rigid solid-outer core = liquid-lower mantle = rigid solid-asthenosphere = liquid (soft solid)-lithosphere = rigid solidPLATE TECTONICS -evidence for plate tectonics (EQs, volcanoes, seafloor age, topography/bathymetry) What is “Plate Tectonics?” Definition: Earth’s lithosphere consists of plates that moveObservations: - Earthquakes and volcanoes happen at plate boundaries. - Topography is the surface shape.- Bathymetry is how deep the oceans are.- age of the seafloorHow do Plate Tectonics work? Answer: through the internal heat of the earthHeat transfer methods:o Conduction: the movement of heat through solid materialo Convection: the movement of heat through substances that flow.  Occurs in the asthenosphere. As this happens the plates underneath are moving.  The lithosphere is also moving. o Where heat is rising, magma is created (this happens between the asthenosphere and lithosphere for example.Types of plate boundaries (you should know the type of motion involved with each, examples of each type of plate boundary, and features found at each boundary) -Divergent Movement: plates are pulling away from each otherExamples:  Mid Atlantic ridge - Is an example of a mid ocean ridge- Caused by sea floor spreading (ocean moving apart)- There are mountains on either side of the boundary causing it to be higher in elevation than the surrounding basins- Moves apart 2-4 inches every year East African rift valley - Rift valleys are caused by continental drifting which will eventually become sea floor spreading Young plate boundaries- East African rift valley- Red seaFeatures: Volcanoes Earthquakes  Mostly found in the ocean-Convergent Movement: plates come together (pushing)Subduction: one plate goes underneath the other. This creates trenches, earthquakes, and volcanoes (on the overriding plate)Oceanic/continentalOceanic goes underneath EQs occur in different depthsAsthenosphere is melting and creating volcanoesExample: cascade mountainsOceanic/oceanicThe heavier one subductsPlates get heavier as they get olderEQsVolcanoes (become volcanic islands)Island arc = chain of volcanoesExample: Aleutian islands, AlaskaContinental Collision Two continents crashMountains are createdA thicker lithosphere is createdEQs up to magnitude 8No volcanic activity Example: Himalayan mountains-Transform Movement: plates moving past each otherFeatures: EQs up to magnitude 7No volcanic activityExample: San Andreas Fault along mid ocean ridges-local plate tectonic setting-What plate are we on in Flagstaff, Arizona? -What plate is Los Angeles (southern California) on? -Hot spots Definition: a stationary point where heat is rising How it works: heat rises from the core/mantle boundaryChain of volcanoes shows the direction the plate is movingUsing volcano ages, we can determine the speed of the plate movingNot all are activeExamples: Hawaii (oceanic plate)Yellowstone (continental)Iceland (hot spot on a plate boundary)-VIDEO: Deadliest Earthquakes 1. Compare the earthquakes in Haiti and Chile. Port Au Prince, Haiti Chile a. What type of plate boundary do they lie near? Transform Plate Boundary Convergent (subduction zone) b. What was the magnitude of each earthquake? M 7.0 M 8.8 c. What was the damage/human casualties (if any) of each earthquake? City reduced to rubble, 233,000 deaths Half a million homes damaged or destroyed Hundreds dead 2. How did Eric Calais (Purdue University) and his colleagues know that a major earthquake was inevitable in Haiti? They have been taking GPS measurements in Haiti since 2003. They have been tracking the movement of the ground in the northern (North American plate) and southern (Caribbean plate) areas in opposite directions.They have used ground movement data to calculate stress levels along the plate boundary. He calculated the amount of elastic strain on the fault. He has calculated ~1.8 meters of movement since the last earthquake, so he knew it was just a matter of time before the rocks broke. In 2008 Calais announced that the Haitian fault could generate an earthquake above magnitude 7. 3. a. Can scientists calculate the amount of pressure (energy) stored along a plate boundary? yes b. Can scientists predict when the fault will break and release the energy? no 4. Which strike-slip fault moves faster, the San Andreas Fault in California or in Haiti? The plates along the San Andreas fault move 3 times faster than in Haiti 5. When was the last lethal earthquake along the San Andreas Fault system? The 1994 Northridge Earthquake 6. How are tsunamis generated? (What type of plate boundary and how?) Megathrusts (Subduction Zone Boundaries) When the fault ruptures the overriding plate punches upward. The uplift raises the sea above, creating a wave that travels across the ocean. 7. What major cities on the northwest coast of the United States are at risk for megathrust earthquakes and tsunamis? Portland, Seattle, Vancouver BC 8. How do core samples of seafloor sand and mud tell us information about past earthquakes? Layers of mud are like a tape recorder, they record everything that happens to the sea floor over time. Undersea earthquakes create huge landslides that coat the sea floor. They deposit distinct, identifiable, sandy layers. Each earthquake sandy layer can be identified, which allows us to gain insights into the timing and frequency of these large earthquakes 9. What are the odds of a megathrust earthquake happening in the Cascadia region in the next50 years? The chance of a megathrust in the next 50 years is “one in three.” 10. a. What is a “silent earthquake?” Where and how do they occur? An earthquake that is


View Full Document
Loading Unlocking...
Login

Join to view Exam 1 Study Guide and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exam 1 Study Guide and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?