A lesson form FEMA/AGU earthquake curriculum for teachers of grades 7-12.
This section is intended to help students observe how stick-slip movement works. Instructions on how to build a motorized version of the following experiment as well as data produced from this model are available.
Earthquakes Be Predicted?"
Some background information
What Happens When the Earth Quakes?
In this unit students will move beyond their own personal survival and that of their community, the focus of Unit 1, to the big picture of earthquakes in space and time. Since the Seismic Sleuths curriculum is intended to supplement, and not to replace, your schools own syllabus, it sketches this big picture without filling in all the basic earth science background. Your preparation to teach these lessons must begin with an assessment of your students readiness. If they have no familiarity with rocks and minerals or with faulting and other processes that form landscapes, you may need to provided a brief introduction from the first few chapters of a high school geology or earth science textbook.
Unit 2 begins with a hands-on activity that models what happens when the stresses accumulated at a fault are released in an earthquake. Using a box, a board, sandpaper, and other simple materials, students apply scientific method and basic math skills to measure movement, calculate averages, and plot their information on a graph.
The second lesson includes three activities and an overview of what is now known about Earths ever-shifting surface and its layered inner structure. In the first activity, students will reproduce the magnetic evidence for the migration of Earths poles in the course of tectonic movement. In the second, they see how this record is written in the rocks at mid-ocean ridges. In the third, they create a map showing the arrangement of the continents 120 million years ago, and compare it with the map of the world today. As students consider several alternative explanations for tectonic plate movement, remind them that earth science, like the Earth it studies, is constantly in motion. Scientific knowledge moves forward through questioning and the development of hypotheses into theories; its goal is never to provide dogmatic answers.
The third lesson begins with an exercise in which students contrast the small scope of historic time with the vastness of geologic time. In the second activity, Paleoseismology, they simulate the techniques seismologists use to read the record of relatively recent earthquakes.
The amount of damage an earthquake causes depends on the strength
and duration of the earthquake, on population density, on methods
of construction (to be dealt with in Unit 4), and on the geophysical/geological
characteristics of the impacted area. Lesson 4 progresses to three
of the most potentially destructive earthquake effects: liquefaction,
landslides, and tsunami. Each occurs when a seismic shock impacts
an area with certain physical characteristics. Lesson 5 underlines
the importance of site, as students interpret maps highlighting
different features of the landscape. They will draw on their new
knowledge to make additions to the local map they began in Unit
Students will operate a model to observe the type of motion that occurs at a fault during an earthquake and explore the effects of several variables.
How much energy will a fault store before it fails?
Is this quantity constant for all faults?
For each small group
To assure success, construct the model ahead of time and rehearse the activity. Then arrange materials for student models in a convenient place.
Explain to students that when an earthquake occurs and movement begins on a fault plane, the movement will not proceed smoothly away from the focus. Any change in the amount of friction along the fault will cause the fault movement to be irregular. This includes changes along the length of the fault and with depth, changes in rock type and strength along the fault, and natural barriers to movement, such as changes in the direction of the fault or roughness over the surface of the fault plane.
Rupture along a fault typically occurs by fits and starts, in a type of sporadic motion that geologists call stick-slip. As energy builds up, the rock on either side of the fault will store the energy until its force exceeds the strength of the fault. When the residual strength of the fault is exceeded, an earthquake will occur. Movement of the fault will continue until the failure reaches an area where the strength of the rock is great enough to prevent further rupture. In this manner, some of the energy stored in the rock, but not all of it, will be released by frictional heating on the fault, the crushing of rock, and the propagation of earthquake waves.
Ask the class:
Created By Dave Love, Chris Durand and John Van Der Kamp
last modified: 9 January, 2007