How to determine principal stress axes from a fault using a stereonet

This video is a step-by-step guide to finding the maximum, intermediate, and minimum principal stress axes (commonly referred to as sigma-1, sigma-2, and sigma-3 respectively) from a given fault orientation (strike/dip of 070/60) and a slip lineation (rake of 90). This video is designed with college-level structural geology students in mind.

0:00 Plot the fault plane & slip lineation
2:27 Visualize the fault & check your work
3:25 Find the maximum principal stress axis
6:56 Find the minimum principal stress axis
8:06 Find the intermediate principal stress axis

Additional resources:
Basic Methods of Structural Geology by Stephen Marshak and Gautam Mitra, Chapter 12 Analysis of Fracture Array Geometry
The textbook used for this class: Structural Geology by Haakon Fossen

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👋 I’m Allison, a structural geologist and Earth Science educator in Northern California. I help college students and geology enthusiasts understand the processes that shape our planet. 🌎

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📀Software: Camtasia 2022

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🧭Compass: Brunton northern hemisphere

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