EOSC 114 Lecture Notes - Lecture 5: San Andreas Fault, Fracture, Thrust Fault

• School: UBC
• Department: Earth and Ocean Sciences
• Course: EOSC 114
• Professor: Brett Gilley

Document Summary

1. thrust (larger displacement) or reverse (smaller displacement) caused by convergent boundary. We are in a convergent boundary setting. Hanging wall block moves upwards relative to footwall. Take away the footwall, hanging wall will fall down. Hanging wall block moves down relative to footwall. Tension: hanging wall is dragged down over the footwall, crust is extended or stretched. San andreas fault is slip strike-slip fault. For slow plate motions, force is applied slowly. So deformation is gradual (failure can be sudden) Earthquakes (faulting, brittle fractures), and can only occur in the lithosphere. Most continental plate earthquakes occur in the upper 15 km. The asthenosphere (and lower mantle) is too ductile for brittle faulting from slow mantle convection forces. Temperature, strength, and geometry are keys to determining if or how "big" a brittle fracture (earthquake fault rupture) will be. You can logically predict for any plate boundary. The type of faulting that would dominate there.