Seismic Refraction Flashcards
What are the 2 types of applied seismology?
- Seismic refraction
- Seismic reflection
What is seismic refraction
Signal returns to surface by refraction and recorded at a distance greater than depth
What is seismic reflection?
Seismic signal reflected back to surface and recorded at distances less than depth
What are the 2 types of strain that can propagate as waves?
- Axial streas
- Shear stress
What is hookes law?
Stress is proportional to strain
What are the 2 types of body waves?
1.P-waves
2. S-waves
What are P-waves?
Where the motion of particles in a solid is the direction of wave propagation (horizontal vibrations). HIGHEST speed
What are S-waves? Why can’t S-waves exist in fluids like water or air?
Particle motion is in plane perpendicular to direction of propagation (vertical vibrations) with no volume change.
Because the fluid is unable to support shear stresses.
What are the 2 types of surface waves?
- Rayleigh waves
- Love waves
What are Rayleigh waves? What happens to the amplitude with depth?
Waves that propagate along the surface of the Earth.
Amplitude decreases a lot with depth
What are love waves? How do they propagate? When do they occur?
Waves that move horizontally and vibrate perpendicular to propagating.
Occur when free surface and deeper interface are present and the shear wave velocity is lower in the top layer
What do seismic wave velocities depend on (3)?
Density
Shear modulus
Axial modulus
In igneous rocks, how does velocity increase?
With increase in mafic content
If there is an increase in porosity, how does that affect the seismic velocity?
Decrease in seismic velocity with increase in porosity
