Earthquake Machine, part 2

Mechanical Modeling to Increase Student

Understanding of Complex Earth Systems

Developed by Michael Hubenthal - IRIS Consortium

Objectives Describe global trends for Earthquake occurrence and magnitude

Interpret a Gutenberg Richter plot (Frequency vs. Magnitude)

Critically analyze an argument

Describe the importance of sharing science results with peers in the science process

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Studying Earthquake Recurrence

Developing arguments….

How many beads are in the box????

Seismic MomentMo = fault length x fault width xdisplacement xrigidity

Moment Magnitude = Mw = log Mo/1.5 – 10.7

Relationship of slip to magnitude

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Seismic MomentMo = fault length x fault width x displacement x rigidity

Visualizing magnitude with the model

B

Moment Magnitude = Mw = log Mo/1.5 – 10.7

In earthquake machine, this means magnitude is directly related to fault displacement

#1“There are long periods of quiet

between earthquakes”

Develop an argument either for or against one statement based on your experimentation with the earthquake machine.

“Most earthquakes are huge, deadly and destructive events”

Extra credit

#2“There hasn’t been an earthquake in a long time; therefore the next one must be huge.”

“There are always long periods between earthquakes.”

“All earthquakes are huge, deadly, and destructive events”

Characteristic Time Predictable

Slip Predictable

Str

ess

Sli

p

Time

Calaveras Fault Data

(Bufe et al., 1977)

Seismicity of the EQ Machine - 67 “Years”

Seismicity of the EQ Machine - 163 “Years”

Summary• There are many more small earthquakes

than large earthquakes

• There are more short time periods between earthquakes than long time periods

• In the earthquake machine, the longer since the last earthquake, the larger the earthquake is likely to be• This isn’t usually true in the Earth

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