Slip-rate across the San Andreas Fault and Seismic hazard estimation for central California
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
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.
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).
More information about assessment tools and techniques.Teaching materials and tips
- Activity Description/Assignment (Microsoft Word 492kB Aug28 07)
- Instructors Notes (Microsoft Word 29kB Jul5 07)
- Solution Set (Microsoft Word 531kB Aug28 07)
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Other Materials
- Reference (Acrobat (PDF) 4.4MB Jul5 07)
- calculations - average (Excel 15kB Jul5 07)
- calculations - dislocation model (Excel 48kB Jul5 07)
- PowerPoint presentation (PowerPoint 1.4MB Aug28 07)
Supporting references/URLs
Schmalzle, G. M., T. Dixon, R. Malservisi, and R. Govers, Strain accumulation across the Carrizo segment of the San Andreas Fault, California: Impact of laterally varying crustal properties, Journal of Geophysical Reasearch, B, Solid Earth and Planets, 111, doi:10.1029/2005JB003843, 2006.