A Model of Three Faults

U.S. Geological Survey

Activity Source:

Groundwork

I of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects. An earthquake is a sudden move of the Earth, caused by the abrupt release of strain that has accumulated over a long time. For hundreds of millions of years, the forces of plate tectonics have shaped the Globe as the huge plates that form the Earth's surface slowly motion over, under and past each other. Sometimes the motion is gradual. At other times, the plates are locked together, unable to release the accumulating energy. When the accumulated energy grows strong enough, the plates break gratuitous. If the convulsion occurs in a populated expanse, it may cause many deaths and injuries and all-encompassing property impairment.

Today we are challenging the assumption that earthquakes must present an uncontrollable and unforecastable hazard to life and property. Scientists take begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest take a chance are beingness identified, and designing structures that will withstand the effects of earthquakes.

Materials

Objective

Students will notice error movements on a model of the earth's surface.

Time Needed

1 or 2 Form periods

Materials Needed (per group)

  • Physiographic map of the world
  • Crayons or colored pencils
  • Pair of scissors
  • Tape or glue
  • Metric ruler
  • Construction paper
  • Error Model Canvas (included)

Instructions

  1. Have students work in pairs or modest groups.
  2. Brandish the fault models in the classroom after the activity.
  3. An fantabulous world physiographic map, showing the sea flooring, can be obtained from the National Geographic Society.

Awarding Phase

  1. Explicate that faults are often (merely not always) institute well-nigh plate boundaries and that each blazon of mistake is frequently associated with specific types of plate movements. Still, you lot can probably find all types of fault movement associated with each type of plate boundary.
    • Normal faults are ofttimes associated with divergent (tensional) boundaries.
    • Thrust faults are often associated with convergent (compressional) boundaries.
    • Strike-slip faults are often associated with transform (sliding) boundaries.
  2. Inquire the following questions:
    • What kind of faults would you wait to notice in the Himalaya Mountains? Why?
    • What kind of faults would you look to find along the Mid-Atlantic Ridge? Why?
    • What kind of fault is the San Andreas Mistake? Is California likely to "fall off into the Pacific Ocean"? Why?
  3. Explain that not all faults are associated with plate boundaries. Explain that there is a broad range of faults based on blazon, linear extension, displacement, historic period, current or historical activeness and location on contintental or oceanic crust. Have students research examples of non-plate boundary faults.
  4. Explain to students that the stresses and strains in the earth's upper layers are induced by many causes: thermal expansion and wrinkle, gravitational forces, solid-earth tidal forces, specific volume changes because of mineral stage transitions, etc. Faulting is ane of the various manners of mechanical aligning or release of such stress and strain.
  5. Have students research and report on the types of faults found in your state.

Extension

  1. Have students Identify the fault movements in the recent Hill Prieta, California earthquake.
  2. Have students research the error histories and recent theories concerning the Northridge, California Earthquake, the New Madrid, Missouri , and the Anchorage, Alaska fault zones.

Coloring Key

  • Rock Layer X - green
  • Rock Layer Y - xanthous
  • Rock Layer Z - red
  • River - blue
  • Road - blackness
  • Railroad tracks - dark-brown
  • Grass - greenish

Part 1

Exploration Phase

  1. You may wish to introduce this activity by asking students:
    • Can you name a famous fault?
    • What happens when giant fractures develop on the Globe and the pieces move relative to one some other?
  2. Illustrate compressive globe movements using a large sponge by squeezing from both sides, causing uplift. Using a piece of latex rubber with a wide mark drawn on it, illustrate world tension, by pulling the ends of the latex to show stretching and thinning.
  3. Have students construct a fault model using the Error Model Sail. Instructions to students:
  4. Color the fault model that is included according to the color central provided.
    • Paste or glue the error model onto a slice of construction paper.
    • Cutting out the fault model and fold each side downward to form a box with the drawn features on peak.
    • Tape or glue the corners together. This box is a three dimensional model of the height layers of the Earth's chaff.
    • The dashed lines on your model represent a fault. Advisedly cut along the dashed lines. Y'all will end up with two pieces. Yous may wish to accept your students tape or glue a slice of construction paper on the side of the two fault blocks along the mistake face. This will help with the demonstration.

    Note that an enlarged version of the mistake block model tin can be fabricated for classroom demonstrations.

  5. Take students develop a model of a normal fault.
    • Instructions to students: Locate points A and B on your model. Move point B so that it is side by side to Point A. Observe your model from the side (its cantankerous-department). Have students draw the normal fault as represented by the model they have just constructed.

Concept Development

  1. Ask the following questions:
    • Which way did point B move relative to bespeak A?
    • What happened to rock layers X, Y and Z?
    • Are the rock layers still continuous?
    • What probable happened to the river? the road? the railroad tracks?
    • Is this type of error caused past tension, compression or shearing?
  2. Explain that this blazon of fault is known as a normal error.
  3. Have students characterization their drawing "normal mistake".
  4. Many normal faults are establish in Nevada. This is considering Nevada is located in a region called the Basin and Range Province where the lithosphere is stretching.

Office 2

Exploration Phase

Have students develop a model of a thrust fault. Instructions to students:

Locate points C and D on your model. Move Betoken C next to bespeak D. Notice the cross-section of your model.
Have students draw the thrust error every bit represented by the model they accept only synthetic.

Concept Development

  1. Ask the post-obit questions:
    • Which way did point D move relative to bespeak C?
    • What happened to rock layers X, Y and Z?
    • Are the rock layers still continuous?
    • What probable happened to the river? the road? the railroad tracks?
    • Is this blazon of fault caused by tension, compression or shearing?
  2. Explain that this type of fault is known equally a thrust fault.
  3. Take students label their cartoon "thrust error".
  4. An example of a thrust error is the mistake in which the Northridge earthquake occurred. The thrusting movement raised the mountatins in the area by as much every bit seventy cm.

Part 3

Exploration Phase

Have students develop a model of a strike-slip fault. Instructions to students:

Locate points F and 1000 on your model. Move the pieces of the model so that point F is next to point Grand.
Have students describe an overhead view of the surface every bit information technology looks after movement along the error.

Concept Development

  1. Inquire the following questions:
    • If you lot were standing at bespeak F and looking beyond the mistake, which fashion did the block on the opposite side motility?
    • What happened to rock layers Ten, Y, and Z?
    • Are the rock layers even so continuous?
    • What likely happened to the river? the road? the railroad tracks?
    • If the scale used in this model is 1 mm = two m, how many meters did the globe motility when the strike-slip fault caused point F to move alongside point G? (Annotation that this scale would make an unlikely size for the railroad track!) If in that location were a sudden horizontal shift of this magnitude it would be about five times the shift that occurred in the 1906 San Andreas fault as a result of the San Francisco earthquake.
    • Is this type of fault caused by tension, compression or shearing?
  2. Explain that this blazon of fault is known as a strike-slip error.
  3. Have students label their drawing "strike-slip fault".
  4. Explain to the students that a strike-slip fault can be described equally having right or left-lateral movement. If yous look directly across the fault, the management that the reverse side moved defines whether the motion is left-lateral or right-lateral. The San Andreas fult in California is a right-lateral strike-slip error.

Model