Pick P Arrivals
45 minIdentify first P onset; note up/down polarity.
Intermediate2-3 hours
P Wave First Motion Guide
Learn p wave first motion from scratch with a clear step-by-step workflow, recommended tools, safety guidelines, and expert tips.
geology studentsanalysts
Workflow
Measure Polarity
1 hourClassify compression (+) or dilatation (−) per station.
Plot Focal Mechanism
1 hourMap polarities on lower hemisphere beachball.
Interpret Style
30 minClassify normal, reverse, or strike-slip faulting.
Checklist
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Planning
Preparation
Safety
Execution
Reference Materials
First MotionStandard
Upward first motion on vertical = compression at source (standard convention).
Takeoff AngleFormula
tan ψ = p × V(depth) relates ray parameter to takeoff angle.
Fault TypesTable
Beachball patterns.
| Pattern | Style | Setting |
|---|---|---|
| Normal | Extension | Rift |
| Reverse | Compression | Subduction |
| Strike-slip | Shear | Transform |
Test First
Always do a test run on scrap material before working on the final piece.
Quality Foundation
Invest time in understanding fundamentals before attempting advanced techniques. A strong foundation ensures better long-term results.
Gradual Progression
Start with basic techniques and standard practices. Increase complexity only as your skills and confidence develop.
Safety Notes
- Do not use beachballs alone for public hazard.
- Take breaks to reduce eye strain.