Locating Earthquake Epicenters
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Questions and Answers

What is the origin of green algae?

  • Before the origin of life
  • 750 million years ago (correct)
  • 65 million years ago
  • During the formation of the first supercontinent

    • What caused the extinction of dinosaurs?

  • Climate change
  • Volcanic activity
  • Asteroid impact (correct)
  • Overhunting by humans

    • What is the process of the Earth's crust being pulled apart called?

  • Subduction
  • Colliding
  • Converging
  • Diverging (correct)

    • What is the source of carbon in rocks on the sea floor?

    <p>Dead plankton</p> Signup and view all the answers

    What are the two general categories of earthquake waves?

    <p>Surface and body waves</p> Signup and view all the answers

    What is the wavelength of a wave?

    <p>The distance between two successive crests or troughs</p> Signup and view all the answers

    What is the difference between a primary wave and a secondary wave?

    <p>Primary waves are faster than secondary waves</p> Signup and view all the answers

    What is the importance of understanding the physics of earthquake waves?

    <p>It helps us understand the interior of the earth</p> Signup and view all the answers

    Why is it necessary to have at least three seismographs to locate an earthquake?

    <p>To triangulate the location of the earthquake</p> Signup and view all the answers

    What is the radial distance of the earthquake from New York based on the information given?

    <p>30,800 miles</p> Signup and view all the answers

    What is the benefit of having more seismographs to locate an earthquake?

    <p>To increase the accuracy of the location</p> Signup and view all the answers

    Who invented the Richter scale?

    <p>Unknown</p> Signup and view all the answers

    What is a seismograph?

    <p>A device that records earthquakes</p> Signup and view all the answers

    What was the first seismograph like?

    <p>A big urn with dragon heads and marbles</p> Signup and view all the answers

    What is the purpose of measuring earthquake waves in all three directions?

    <p>To determine the direction of the earthquake</p> Signup and view all the answers

    What causes the melting of plates during subduction?

    <p>The mixture of water and sediments</p> Signup and view all the answers

    What is a seismogram?

    <p>A piece of paper that records seismic waves</p> Signup and view all the answers

    What is the purpose of analyzing carbon in marine organisms?

    <p>To study the origin of plate tectonics</p> Signup and view all the answers

    What is the function of the acceleration sensor in a phone?

    <p>To detect movement and orientation</p> Signup and view all the answers

    What is the purpose of using earthquake waves to determine the epicenter?

    <p>To determine the location of the earthquake's epicenter</p> Signup and view all the answers

    What is the significance of the gap between the earthquake waves reaching different seismic stations?

    <p>It reflects the distance between the earthquake's epicenter and the stations</p> Signup and view all the answers

    How do scientists measure the distance between the earthquake's epicenter and the seismic stations?

    <p>By timing how long it takes for the earthquake waves to reach each station</p> Signup and view all the answers

    What is the source of information used to make the graph of distance versus time?

    <p>Nuclear explosions</p> Signup and view all the answers

    What type of wave travels through solids, liquids, and gases?

    <p>P-waves</p> Signup and view all the answers

    What is the difference between P-waves and surface waves?

    <p>P-waves only travel through solids while surface waves travel through all three states of matter.</p> Signup and view all the answers

    How do seismologists locate the epicenter of an earthquake?

    <p>By measuring the time difference between the arrival of P-waves and S-waves.</p> Signup and view all the answers

    What does a seismogram show?

    <p>The time of arrival of the seismic waves.</p> Signup and view all the answers

    What is the frequency of massive earthquakes?

    <p>Once a year</p> Signup and view all the answers

    What is the largest earthquake mentioned in the text?

    <p>Chile, 1916</p> Signup and view all the answers

    What is the extent of damage caused by earthquakes felt by humans?

    <p>Minor property damage</p> Signup and view all the answers

    What is the Richter magnitude scale used for?

    <p>Measuring the amount of motion during an earthquake</p> Signup and view all the answers

    What is the issue with the Richter magnitude scale?

    <p>It measures the total energy released by an earthquake inaccurately</p> Signup and view all the answers

    What is the Moment magnitude scale derived from?

    <p>The total energy released by an earthquake</p> Signup and view all the answers

    Why is the Richter magnitude scale still used today?

    <p>It is easier to understand for the general public</p> Signup and view all the answers

    What is the purpose of the Modified Mercalli Intensity Scale?

    <p>To show how structures behaved during an earthquake</p> Signup and view all the answers

    What is the main difference between the Intensity Scale and the Richter Scale?

    <p>The Intensity Scale measures the damage caused by an earthquake, while the Richter Scale measures the magnitude of an earthquake</p> Signup and view all the answers

    What is the relationship between the Richter Scale and the amount of shaking during an earthquake?

    <p>A magnitude 6 earthquake is 10 times more shaking than a magnitude 5 earthquake</p> Signup and view all the answers

    What is the relationship between the Richter Scale and the amount of energy released during an earthquake?

    <p>A magnitude 6 earthquake releases 32 times more energy than a magnitude 5 earthquake</p> Signup and view all the answers

    What is liquefaction?

    <p>The process of water coming out of the ground due to shaking, destroying foundational support and causing buildings to collapse.</p> Signup and view all the answers

    What is the main cause of tsunamis?

    <p>A wave of water that is pushed up by vertical motion.</p> Signup and view all the answers

    What is the relationship between plate boundaries and earthquakes?

    <p>Earthquakes occur in specific areas along plate boundaries, which define the edges of tectonic plates.</p> Signup and view all the answers

    What is the Cascadia mega thrust?

    <p>An area where tsunamis can develop due to the subduction of one plate beneath another.</p> Signup and view all the answers

    What is the density of water in grams per cubic centimeter?

    <p>1.0</p> Signup and view all the answers

    What is the density of granitic rock compared to water?

    <p>2.7 times more dense</p> Signup and view all the answers

    Why is continental crust older than oceanic crust?

    <p>Continental crust is made up of leftover pieces from supercontinents</p> Signup and view all the answers

    Which layer of the Earth is considered solid despite its flowing nature?

    <p>The mantle</p> Signup and view all the answers

    What drives tectonic activity in the Earth's crust?

    <p>Convection in the outer core</p> Signup and view all the answers

    What factors are considered when generating a hazard map?

    <p>Proximity to faults</p> Signup and view all the answers

    What caused the Mississippi River to change direction during the New Madrid earthquake?

    <p>Earthquake-induced liquefaction</p> Signup and view all the answers

    What is the primary difference between oceanic and continental crust?

    <p>Oceanic crust is denser and mainly composed of basalt, while continental crust is primarily composed of granitic rocks</p> Signup and view all the answers

    What is the thickest layer of the Earth?

    <p>The mantle</p> Signup and view all the answers

    What is the purpose of building redesign and retrofitting, as well as earthquake warning systems?

    <p>To minimize damage and save lives in the event of an earthquake</p> Signup and view all the answers

    What is the significance of the shadow zone created by S-waves?

    <p>It indicates the presence of a liquid layer</p> Signup and view all the answers

    Study Notes

    Earthquakes and Their Impact

    • Earthquakes release massive amounts of energy, with some natural phenomena like lightning bolts and tornadoes releasing equivalent amounts.
    • The size and duration of an earthquake determine its intensity, but the nature of the material and design of structures are also important factors in determining damage.
    • Liquefaction occurs when shaking causes water to come out of the ground, destroying foundational support and causing buildings to collapse.
    • Factors that contribute to damage include poorly built structures, fires caused by broken gas lines, and tsunamis caused by underwater earthquakes, explosions, or landslides.
    • Tsunamis are caused by a wave of water that is pushed up by vertical motion, and they can move at speeds of up to 500 miles per hour.
    • Earthquakes occur in specific areas along plate boundaries, which define the edges of tectonic plates.
    • The depth of earthquakes is related to the angle of the plate, with shallow earthquakes occurring near the edge and deep earthquakes occurring further away.
    • There is currently no reliable way to predict earthquakes, with predictions based on historical data and patterns.
    • Chile is an example of a country that is well-prepared for earthquakes, with reinforced buildings and infrastructure.
    • The 1906 San Francisco earthquake caused a lot of damage due to fires caused by broken gas lines.
    • The Cascadia mega thrust is a prime area for tsunamis to develop due to the subduction of one plate beneath another.
    • Landslides can also be caused by earthquakes and can have devastating effects, as seen in the 1980 Mount St. Helens eruption.

    Understanding Earthquakes and Using Waves to See Inside the Earth

    • Animals behaving differently before an earthquake is not a reliable predictor of earthquakes, as they may sense lower frequency waves than humans.
    • Sediments from layers of earth can be radiocarbon dated to determine the exact dates of previous earthquakes, providing a sense of when they occur.
    • Earthquake prediction for the future is not possible, but building redesign and retrofitting, as well as earthquake warning systems, can minimize damage and save lives.
    • Earthquake waves can be used to see inside the Earth, similar to how sonograms are used to see inside humans.
    • Earthquake waves bend and refract differently depending on the density of the materials they pass through, allowing scientists to identify the difference between waves that have been double reflected or refracted.
    • Primary waves (P-waves) and secondary waves (S-waves) behave differently when passing through solids and liquids, allowing scientists to determine the properties of the Earth's layers.
    • S-waves are stopped completely by liquids, creating a shadow zone that indicates the presence of a liquid layer.
    • Earth's crust is the thin outer rocky layer, with oceanic crust being about five miles thick and continental crust being about 40 miles thick.
    • Continental crust is primarily composed of granitic rocks, while oceanic crust is denser and mainly composed of basalt.
    • The mantle is the thickest layer of the Earth, and the outer core is a liquid layer that creates the Earth's magnetic field.
    • The inner core is a solid layer, and the temperature and pressure increase towards the center of the Earth.
    • Understanding the Earth's layered structure and properties is possible because of the study of earthquake waves and their interactions with different materials.

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    Description

    Test your knowledge on using earthquake waves to determine the epicenter in this quiz. Learn about the graph used and how seismic stations can help locate the origin of an earthquake. Keywords: earthquake waves, epicenter, seismographs, seismic stations.

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