fault

• Fault - a fracture or zone of fracture between two blocks of rocks.
• Epicenter - the point on the earth's surface vertically above the focus of an earthquake.
• Focus - point inside the earth where the earthquake started
• Seismic wave - just like a wave that transports energy from one place to another
• How to know if there is a fault?

  • There must be a movement between two blocks
  • Ex. The layers of sand and starch moved along with the cut/fracture/crack which represents fault.
• • A fault is a fault when there is a cut/fracture/crack on the surface which allows movement of the blocks of rocks.
• Fault Plane - Surface that the movement has taken place within the fault 

  • The plane that represents a fault's fracture surface.
• Hanging Wall - The rock mass resting on the fault plane

  • the upper or overhanging wall of a vein, fault, or other geologic feature.
  • opposed to footwall.
• Footwall - The mass of rock below the fault plane

  • the rocks beneath a fault plane that is inclined
  • Where we walk
• Normal Fault

  • The hanging wall moves down relative to the footwall
  • Younger rocks are displaced above older blocks
  • Fault displaced caused by tension/extension/ pulling apart.
• Reverse Fault 

  • Hanging walls moves up relative to the footwall
  • Older rocks are displaced above younger blocks
  • Fault displacement caused by contraction or pushing together
• Strike - slip fault

  • The plane of displacement is HORIZONTAL
  • Displacement occurs laterally, parallel to the strike of the fault, rather than up or down (parallel to each other)
  • Displacement caused by shearing or sliding past each other
• Active Fault 

  • a fault that is likely to have another earthquake sometime in the future.
  • Earthquake within 10k years
• Inactive Fault

  • No record in 10k years
  • Can still be active
  • Structures that we can identify, but which do not have earthquakes. These faults do not show any signs.
• Tensional Stress - When rocks are pushed away from each other
• Compressional Stress - Towards each other created on the Earth’s surface
• Shear Stress - Pushed perpendicular to the axis