Earthquakes Teacher Guide

Unit

Earthquakes

Subject

Earth and Space Science

Grade Level

MS

Activity Name(s)

Comparing Earthquake Depth and Magnitude Patterns Around the World

Earthquakes Around the World

Investigating Plate Boundaries

Seismic Waves Study

Being Prepared

These activities are computer simulations that work only on a Windows machine, as close as one to one with computers is best. If you are an Apple school then you may need to do the simulation for the class. Another option is to go to the USGS site and evaluate the data without the simulations. Review these activities to see how this will work best for your situation.

Directions for the simulations are detailed but may require student direction before the activities.

If small groups are needed keep groups to a maximum of three for the best participation by all students.

Getting Started

No special equipment is required other than a Windows computer to run the simulations. If you do not have access to a Windows computer then you can go to the USGS (http://earthquake.usgs.gov/earthquakes/map/) site and get the latest information for your area to set up your own model.

Suggested Timeline

Comparing Earthquake Depth and Magnitude Patterns around the World - Have students load the program before the activity and test that it will run, then the activity should take approximately 60 minutes.

Earthquakes Around the World - Have students load the program before the activity and test that it will run, then the activity should take approximately 70 minutes.

Investigating Plate Boundaries - Have students load the program before the activity and test that it will run, then the activity should take approximately 70 minutes.

Seismic Waves Study - Have students load the program before the activity and test that it will run, then the activity should take approximately 70 minutes.

Thinking about the Discovery Questions

Earthquakes have important scientific and historical significance. This unit focuses on the connections between earthquake depth, magnitude, patterns and how seismic waves travel through different parts of the earth. The first activity "Comparing Earthquake Data" introduces students to a data bank and allows them to explore the question "Are there patterns to the depth and magnitude of earthquakes around the world?". In the next activity, "Earthquake Around the World", the students begin looking for patterns in where earthquakes and volcanoes occur answering the question, "Where do most earthquakes and volcanoes occur in the world and why?". The theory of Plate Tectonics describes the lithosphere as divided into a number of crustal plates, which move on the plastic asthenosphere more or less independently to collide with, slide under, or move past adjacent plates. In the third activity in this unit students investigate the question, "How does the direction of plate movement relate to the patterns of earthquakes observed around the world?". The differences in the way seismic waves move and what they reveal about the earth's structure is the focus of the final activity " Seismic Waves Study". The focus question asks "What does the movement of different kinds of seismic waves reveal about Earth's structure?".

Misconceptions

While investigating a number of misconceptions about them may be revealed. Students might believe that the timing of large earthquakes can be predicted, but that is an ongoing challenge for scientists. They may also have heard that earthquakes only happen during certain times of the day or during certain weather conditions. Since earthquakes happen deep with in the earth they have no connection to the time of day or the weather. Another common misconception is the belief that small earthquakes release energy that will prevent larger quakes from occurring. While this is a comforting notion it is important to remember that take 32 3.0 quakes to release the energy of 4.0 and 1000 3.0 quakes to equal a 5.0. So small quakes may release some of the stress on a fault line it doesn't eliminate the risk of a large quake.

Learning Objectives

• NGSS
  • Performance Expectations
    • MS-ESS2-1. Develop a model to describe the cycling of Earth's materials and the flow of energy that drives this process.
    • MS-ESS2-2. Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales.
    • MS-ESS2-3. Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
    • MS-ESS3-2. Analyze and interpret data on natural hazards to forecast future catastrophic events and inform the development of technologies to mitigate their effects.
  • Disciplinary Core Ideas
    • MS-ESS2: Earth's Systems
      • ESS2.A: Earth Materials and Systems
        • All Earth processes are the result of energy flowing and matter cycling within and among the planet’s systems. This energy is derived from the sun and Earth’s hot interior. The energy that flows and matter that cycles produce chemical and physical changes in Earth’s materials and living organisms. (MS-ESS2-1)
        • The planet’s systems interact over scales that range from microscopic to global in size, and they operate over fractions of a second to billions of years. These interactions have shaped Earth’s history and will determine its future. (MS-ESS2-2)
      • ESS2.B: Plate Tectonics and Large-Scale System Interactions
        • Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth’s plates have moved great distances, collided, and spread apart. (MS-ESS2-3)
      • ESS2.C: The Roles of Water in the Earth's Surface Processes
        • Water’s movements — both on the land and underground — cause weathering and erosion, which change the land’s surface features and create underground formations. (MS-ESS2-2)
  • Practices
    • Developing and using models
      • Develop and/or use a model to predict and/or describe phenomena.
    • Analyzing and interpreting data
      • Analyze and interpret data to provide evidence for phenomena.
      • Analyze and interpret data to determine similarities and differences in findings.
    • Constructing explanations and designing solutions
      • Construct a scientific explanation based on valid and reliable evidence obtained from sources (including the students’ own experiments) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.
  • Cross Cutting Concepts
    • Patterns
      • Students recognize that macroscopic patterns are related to the nature of microscopic and atomic-level structure. They identify patterns in rates of change and other numerical relationships that provide information about natural and human designed systems. They use patterns to identify cause and effect relationships, and use graphs and charts to identify patterns in data.
    • Scale, proportion, and quantity
      • Students observe time, space, and energy phenomena at various scales using models to study systems that are too large or too small. They understand phenomena observed at one scale may not be observable at another scale, and the function of natural and designed systems may change with scale. They use proportional relationships (e.g., speed as the ratio of distance traveled to time taken) to gather information about the magnitude of properties and processes. They represent scientific relationships through the use of algebraic expressions and equations.
    • Stability and change
      • Students explain stability and change in natural or designed systems by examining changes over time, and considering forces at different scales, including the atomic scale. Students learn changes in one part of a system might cause large changes in another part, systems in dynamic equilibrium are stable due to a balance of feedback mechanisms, and stability might be disturbed by either sudden events or gradual changes that accumulate over time.
• NSES
  • Earth and Space Science – Structure of the Earth System
    • The solid earth is layered with a lithosphere; hot, convecting mantle; and dense, metallic core.
    • Lithospheric plates on the scales of continents and oceans constantly move at rates of centimeters per year in response to movements in the mantle. Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.
    • Land forms are the result of a combination of constructive and destructive forces. Constructive forces include crustal deformation, volcanic eruption, and deposition of sediment, while destructive forces include weathering and erosion.

Discussion: Setting the Stage

• How do we measure the strength of an earthquake?

  Scientist use a sensitive device call a seismography that measures the movement of the earth.

• Where do most earthquakes occur on the earth?

  Most earthquakes occur along the edges of plate boundaries. It is important to point out that while we know a lot about the location of plate boundaries we continue to add new information all the time.

• How do earthquake waves move?

  P (primary) waves move like a compressed spring (push and pull) and can move through solids and liquids. S (secondary) waves move up and down and can not move through liquids. S-waves are the waves we would feel during an earthquake.

• What is the relationship between earthquakes and volcanoes?

  Earthquakes and volcanoes are may be found in similar areas on plate boundaries. Volcanoes may also be found over hot spots such as the volcanoes that formed the Hawaiian Island chain.

Discussion: Formative Questions

Comparing Earthquake Depth and Magnitude

• Explain the difference between convergent and divergent boundaries.

  Convergent boundaries are where 2 plates at pushing against each other causing one plate to override the other. Divergent boundaries are boundaries are where 2 plates are moving away from each other, stretching the Earth's crust.

Earthquakes Around the World

• Do earthquakes and volcanoes generally correspond to plate boundaries?

  Earthquakes and volcanoes are usually located along plate boundaries.

• How might you explain the volcanic eruptions that occur away from the plate boundaries in the middle of the Pacific Ocean?

  There are hot spots not located on plate boundaries where volcanoes occur.

Investigation Plate Boundaries

• Is there a relationship between the magnitude of an earthquake and the type of plate boundary on which it occurs?

  The largest earthquakes occur near plate boundaries where one plate is colliding with another, convergent boundaries. Most earthquake occur near ocean ridges where the plates are pulled apart, divergent boundaries, margins where the plates scrape past one another, transform boundaries, and margins where one plate is thrust under the other, convergent boundary with a subduction zone.

Seismic Waves Study

• How do P and S waves move through the earth?

  P waves moves through the earth in a compression like a spring. S waves move up and down similar to a rope being whipped up and down.

Discussion: Wrapping Up

• How can P and S waves help with the discovery of the composition of different layers of the earth?

  S waves only move through solids, while P waves can move through solids and liquids so the timing of the waves can be used to determine whether the wave is traveling through a solid or liquid.

• Where do most earthquakes occur in the world?

  Most earthquakes occur along the edges of plate boundaries.

• Where are most volcanoes located?

  Most volcanoes are found along the edges of plate boundaries.

• In 2011 a 5.8 earthquake occurred near Washington, D.C. Since there is not a plate boundary near there, how would explain this quake?

  Earthquakes can also happen within larger plates along smaller fault lines.

Additional Background

Earthquakes are caused by a sudden slip along a fault boundary. We are most familiar with the large boundaries along the tectonic plates. For example, California has two large plate boundaries that come together, the North American Plate and the Pacific Plate. There also a number of smaller fault boundaries. If you look an quake summary map of the United States (http://earthquake.usgs.gov/earthquakes/states/us_damage_eq.php) you can see where some of these smaller faults may lie.

There are 3 types of fault boundaries and each produces its own type of quake. Strike-slip faults produce strike-slip quakes. Strike-slip faults are vertical or near vertical blocks that move horizontally in relation to each other. The other two quakes occur at slip-dip faults. Dip-slip faults occur where there is inclined fracture. A normal quake occurs when the rock above the inclined fracture moves down. A thrust quake occurs when the reverse movement takes place along the fault, cause the rock above the fault to move up.

Go to the USGS site - http://earthquake.usgs.gov/learn/topics/ - for more information on earthquakes.

To create your own model of earthquakes, see http://earthquake.usgs.gov/earthquakes/map/

Analysis

Comparing Earthquake Depth and Magnitude Patterns Around the World

• Are there any earthquakes near divergent boundaries with depths greater than 150 km? Why do you think this is?

  No, because there is less movement at depth so the earthquake occurs where there is more pressure and movement, which is shallower.

• In general, how do the earthquake depths change as you move farther away from the boundaries?

  The deepest earthquakes generally occur at plate boundaries and get shallower as you move away from the boundaries.

• Where do you see more large earthquakes: near divergent boundaries or near convergent boundaries? Why?

  More large earthquakes occur at convergent boundaries since one plate is being pushed under another. Friction between the plates as one plate is being sub-ducted under the other.

• Compare the locations of large earthquakes to the location of deep earthquakes. Do they occur together or are they found in different places? Explain your findings.

  The largest and the deepest earthquakes are not usually found in the same area, largest earthquakes are generally found near convergent boundaries and are shallower.

Earthquakes Around the World

• Which parts of the United States appear to have the most frequent earthquakes?

  Along the plate boundaries which is along the coast of the Pacific Ocean and closely inland from there.

• Where are most volcanoes located?

  Along the plate boundaries which is along the coast of the Pacific Ocean and closely inland from there.

• Why don't earthquakes and volcanoes line up exactly on the plate boundaries?

  Faults can occur in different areas other than the plate boundaries.

• Is there a relationship between the magnitude of an earthquake and the type of plate boundary on which it occurs?

  There is a relationship between the magnitude of an earthquake and the type of plate boundary. Larger magnitude earthquakes tend to occur at convergent plate boundaries smaller magnitude earthquakes tend to occur at divergent plate boundaries.

• Why is it easier to predict where an earthquake will occur than it is to predict when it will occur?

  It is easier to predict where an earthquake will occur based on the type and action of the plate boundaries. When the earthquake will occur is tougher to do since build up is unknown.

• Why do you think volcanoes are included in this model?

  Volcanoes are included to show the relationship between their location and where earthquakes occur, along the plate boundaries.

Investigating Plate Boundaries

• How does the movement of plates along a divergent boundary account for the patterns of earthquakes you saw? Explain.

  The quakes along the divergent boundaries tended to be shallower. Since the plates are stretching the areas where the quakes occur are near teh surface fo the earth's crust.

• How does the movement of plates along a convergent boundary account for the patterns of earthquakes you saw? Explain.

  Quakes along the convergent boundaries can be both shallow and deep. If there is subduction occurring quakes will happen at different depths depending on where the plates end up slipping.

• How does the movement of plates along a transform boundary account for the patterns of earthquakes you saw? Explain.

  As the plates slide past each other in transform boundaries you get shallow quakes that may be very powerful with much of the energy released close to the surface.

• Which plate movements tend to produce the strongest earthquakes?

  Both convergent and transform faults can produce equally strong earthquakes. Those that happen along transform faults tend to be more destructive since the energy released is closer to the surface.

Seismic Waves Study

• Which waves travel fastest through the mantle: Primary waves or Secondary waves?

  Primary waves travel fastest through the mantle.

• Describe what happens when the first P wave hits the boundary of the outer core. Describe what happens when the first S wave hits the boundary of the outer core.

  When the P wave hits the boundary of the outer core there is slight refraction or bend and then it continues through the core. The first S waves when they hit the outer core are reflected away.

• What types of waves make it to the opposite side of Earth (relative to the location of a particular earthquake)?

  P waves will make it to the other side of the Earth, since they can travel through liquid.

• What are the different characteristics of the mantle, outer core, and inner core? What evidence do you have to support your assessment of the different characteristics of each layer? Are all the layers the same? How can you tell?

  The mantle is solid allowing both P and S waves to pass through it. The outer core is liquid since P waves and not S waves can pass through it. The inner core is solid since as the P waves pass from the outer to inner core there is a slight reflection before the wave continues through.

• Why do you think the core of the Earth is liquid while the crust is solid?

  Answers will vary, but should relate the intense heat that is produced under the pressure of the material above would melt material or keep it liquid.

Further Investigation

Compile lists of local earthquakes, or ones of concern, have students put into a spreadsheet and plot onto a map of the earth. Alternative is to create your own simulation with the above data.

Create a map or simulation that contains earthquakes and volcanoes. Noting the latitude, longitude, magnitude and depth of earthquakes as well as the latitude, longitude and recent activity status for volcanoes.

Online earthquake resources:

• USGS, Alaska Volcano Observatory - http://www.avo.alaska.edu
• Cascade Volcano Observatory - http://volcanoes.usgs.gov/observatories/cvo/
• California Volcano Observatory - http://volcanoes.usgs.gov/observatories/calvo/
• Yellowstone Volcano Observatory - http://volcanoes.usgs.gov/observatories/yvo/index.html