luokai0 Geophysics Expert
Before Starting
- Solid Earth or exploration geophysics?
- Which method? (seismic, gravity, EM, MT)
- Forward modeling or inversion?
Core Expertise Areas
Earth Structure
Crust: continental (35 km avg, granitic) and oceanic (7 km, basaltic). Mantle: upper (solid, peridotite) and lower, separated by transition zone. Core: outer (liquid iron-nickel, generates magnetic field) and inner (solid). Seismic discontinuities: Moho (crust-mantle), 410 and 660 km (phase transitions).
Seismic Methods
Body waves: P-waves (compressional) and S-waves (shear, not through liquids). Surface waves: Rayleigh and Love waves, dispersive, used for shallow structure. Reflection seismics: record reflections from interfaces, used in exploration. Refraction seismics: first arrivals, velocity structure, shallow applications. Tomography: 3D velocity models from travel time inversions.
Gravity and Magnetics
Gravity anomaly: deviation from reference ellipsoid after corrections. Bouguer correction: removes effect of topographic mass. Magnetic anomaly: deviation from IGRF reference field. Magnetic reversals: polarity chrons used for seafloor spreading rate dating.
Electromagnetic Methods
Resistivity: measures electrical resistance of subsurface. MT: magnetotellurics — natural EM fields probe deep conductivity structure. GPR: ground-penetrating radar, high resolution shallow imaging. EM induction: frequency-domain and time-domain methods for conductors.
Best Practices
- Apply all necessary corrections before interpreting data
- Integrate multiple methods to reduce non-uniqueness
- Constrain inversions with geological information
- Assess uncertainty in all geophysical models
Common Pitfalls
| Pitfall | Fix |
|---|---|
| Non-uniqueness in inversions | Use multiple methods and geological constraints |
| Missing terrain corrections | Always apply free-air and Bouguer corrections |
| Confusing P and S wave arrivals | Use polarization analysis and moveout patterns |
| Static corrections in reflection seismic | Apply datum and refraction statics |
Related Skills
- geology-expert
- seismology-expert
- physics/fluid-physics-expert