Teach the Earth > Geophysics > Teaching Activities > Interseismic deformation: Crustal deformation between large earthquakes

Slip-rate across the San Andreas Fault and Seismic hazard estimation for central California

Shimon Wdowinski
,
University of Miami
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

• Scientific Accuracy
• Alignment of Learning Goals, Activities, and Assessments
• Pedagogic Effectiveness
• Robustness (usability and dependability of all components)
• Completeness of the ActivitySheet web page

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.

Summary

This assignment is based on real geodetic data measured in central California across the San Andreas Fault. It will get the students acquainted with geodetic observations, basic data analysis methods, and earthquake mechanics.

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Context

Audience

upper level undergraduate class in geophysics for geology major (limited quantitative background)
Designed for a geophysics course

Skills and concepts that students must have mastered

The assignment is based on some knowledge about crustal deformation, the earthquake deformation cycle, and geodetic observations.

The assignment requires prior knowledge/skills in the followings:
1. Basic math—what is arctan, and its range of solutions (-pi/2 to pi/2).
2. Basic physics—what is vector, decomposing vectors into two components.
3. Basic statistics—Calculating average and standard deviations. Something that not too many people know adding uncertainties, when adding or subtracting vectors. In that case, we add the variance (standard-div**2) of each vector. The new uncertainty is square-root of the added variances.
4. Basic programming and plotting skills—Excel, Matlab, or any other program. The assignment can also be solved with paper and pencil, but it is not recommended.

How the activity is situated in the course

part of a sequence of assignments

Goals

Content/concepts goals for this activity

Calculating (i) interseismic slip-rate across the San Andreas Fault and (ii) seismic hazard assessment for central California

Higher order thinking skills goals for this activity

comparison between models, estimating best-fit between observations and model, conducting sensitivity studies

Other skills goals for this activity

working in groups (optional), promoting basic programming and plotting skills—Excel, Matlab, or any other program.

Description of the activity/assignment

In this assignment the students need to calculate the interseismic slip-rate across the San Andreas Fault using three methods: nearest stations, average, and locked-fault model. The solution for the first method is straightforwards. The solution using the second method requires basic knowledge in statistics. The solution using the third and more realistic method requires basic programming and plotting skills. Comparison between calculated models and observations yields model improvement and better estimates of the intersesimic rates. Based on the slip-rate calculations and additional seismic observations, the student sould estimate the surface rupture, rupture length, and moment magnitude of the next large earthquake in central California.

Determining whether students have met the goals

The student should solve correctly the first two methods (nearest stations and average) and show serious attents to solve using the third methods (locked fault model).