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Earthquake Machine. Mechanical Modeling to Increase Student Understanding of Complex Earth Systems. Michael Hubenthal - IRIS Consortium. What is an Earthquake?. Write down a definition for an earthquake.
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Earthquake Machine Mechanical Modeling to Increase Student Understanding of Complex Earth Systems Michael Hubenthal - IRIS Consortium
What is an Earthquake? Write down a definition for an earthquake In small groups, discuss your definitions of an earthquake and create a consensus definition
B EQ Machine - Lite Bulk of the Plate Top View C Elastic Properties of Earth Materials Plate has Constant Velocity Here Edge of the Plate
What did you observe? How would you alter your definition, to accommodate these observations?
Centennial Connections During the 1906 event the earth on one side of the fault had slipped compared to the earth on the other side of the fault by up to 21 feet (7 m). Steinbrugge Collection of the UC Berkeley EERC
After studying the fault trace of the 1906 earthquake and regional surveys (pre/post event), Harry Fielding Reid, postulated that the forces causing earthquakes were not close to the earthquake source but very distant.
Elastic Rebound Theory Distant forces cause a gradual build up of stress in the earth over tens or hundreds or thousands of years, slowly distorting the earth underneath our feet. Eventually, a pre-existing weakness in the earth--called a fault or a fault zone--can not resist the strain any longer and fails catastrophically.
http://quake.wr.usgs.gov/research/deformation/modeling/animations/index.htmlhttp://quake.wr.usgs.gov/research/deformation/modeling/animations/index.html
Key Concepts • Elastic materials can store potential energy • Earth materials are elastic though they may not seem it within our temporal and thermal scales • The Earth’s plates are constantly in motion though we can not perceive this without instruments
Seismic Moment Mo = fault length x fault width x displacement x rigidity Moment Magnitude = Mw = log Mo/1.5 – 10.7
B Visualizing magnitude with the model Seismic Moment Mo = fault length x fault width x displacement x rigidity Moment Magnitude = Mw = log Mo/1.5 – 10.7
Event # Time Displacement Examine page one of your data set and develop a prediction for the 26th event based on the previous 25 events.
Components of Prediction • When? • Where • How Big?
Using the data you have collected argue either for or against the following statement… “There hasn’t been an earthquake in a long time; therefore the next one must be huge.”
Time Predictable Slip Predictable Characteristic Stress Slip Time
Calaveras Fault Data (Bufe et al., 1977)
For a full description of the EQ Machine and a multi-period lab please visit: http://www.iris.edu/edu/lessons.htm 2008 Hubenthal, M., Braile, L., Taber, J. Redefining earthquakes & the earthquake machine. The Science Teacher, 75(1), 32-36.
Young students ideas (Ross and Shuell, 1991) (Tsai, 2001) (Leather, 1987)
Conceptual shift at age 14? (Barrow & Haskings, 1996; DeLaughter et al., 1998; Libarkin et al., 2005))