Earthquake Machine

Earthquake Machine

Mechanical Modeling to Increase Student

Understanding of Complex Earth Systems

Michael Hubenthal - IRIS Consortium

Objectives (SWBAT)Explain earthquakes as a part of the natural Earth System Describe global trends for Earthquake occurrence and magnitudeInterpret a Gutenberg Richter plot (Frequency vs. Magnitude)Critically analyze an argumentDescribe the importance of sharing science results with peers in the science process

Write down a definition for an earthquake

What is an Earthquake?

In small groups, discuss your definitions of an earthquake and create a consensus definition

Exp

lori

ng w

ith

a m

odel

…

B

C

EQ Machine - Lite

Top View

Bulk of the Plate

Edge of the Plate

Elastic Properties of Earth Materials Plate has

Constant Velocity Here

How would you alter your definition, to accommodate these observations?

What did you observe?

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.

Elastic Rebound Theory

http://quake.wr.usgs.gov/research/deformation/modeling/animations/index.html

Key Concepts Elastic materials can store potential energyEarth materials are elastic though they may not seem it within our temporal and thermal scalesThe Earth’s plates are constantly in motion though we can not perceive this without instruments

Studying Earthquake Recurrence

Developing arguments….

How many beads are in the box????

Exp

lori

ng w

ith

a m

odel

…

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

Moment Magnitude = Mw = log Mo/1.5 – 10.7

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

Group A“There are long periods of quiet

between earthquakes”

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

*Note: You must base our argument on minimally 30 events

“Most earthquakes are huge, deadly and

destructive events”

Group B

Earthquake Frequency

0

5

10

15

20

25

1-2 Years 3-4 Years 5-6 Years 7-8 Years 9-10Years

11-12Years

13-14Years

15-16Years

Time Between Events

Earthquake Count

Count

“There are always long periods between earthquakes.”

Earthquake Size Distribution

0

2

4

6

8

10

12

14

16

18

20

0-1.99 2-3.99 4-5.99 6-7.99 8-9.99 10-11.99

12-13.99

14-15.99

16-17.99

18-19.99

20-21.99

22-23.99

24-25.99

26-27.99

Magnitude (Slip CM)

Count Earthquake

Frequency

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

Frequency/Magnitude Relationship

2.7 2.84.1

5.3

7.38

12.6

3.6

27.8

0.7 1 0.71.7

4.4

8

12.6

3.6

27.8

1.5 1.82.7

3.9

6.3

8

12.6

3.6

27.8

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9

Years Between Events

Magnitude (Slip CM)

Characteristic

Time Predictabl

e

Slip Predictab

le

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

Young students ideas

(Ross and Shuell, 1991)

(Leather, 1987)

(Tsai, 2001)

Conceptual shift at age 14?

(Barrow & Haskings, 1996; DeLaughter et al., 1998; Libarkin et al., 2005))

Location of EQs & relation to plates

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).

Centennial Connections

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.

Examine page one of your data set and

develop a prediction for the 26th event

based on the previous 25 events.

Event #

Time Displacement

0

2

4

6

8

10

12

14

Time (Years)

Displacement (cm)

Seismicity of the EQ Machine - 67 “Years”

0

5

10

15

20

25

30

Seismicity of the EQ Machine - 163 “Years”