15.1 Flashcards
Stress
the total force acting on crustal rocks per unit area
3 kinds of stress that act on Earth’s rocks
compression, tension, and shear
compression
decreases volume of the material
tension
pulls the material apart
shear
causes material to twist
strain
the deformation of materials in response to stress
Elastic deformation
causes materials to bend and stretch, proportional to stress
Plastic deformation
permanent deformation caused by strain when stress exceeds a certain value
Fault
fracture or system of fracture in Earth’s crust that occurs when stress is applied too quickly or stress is too great
reverse fault
form as a result of horizontal and verticle compressions that squeezes rock and causes verticle movement upward along a fault plane
normal faults
form as a result of horizontal and verticle tension that pulls on the rock and causes verticle movement along a fault plane
strike skip fault
caused by horizontal shear in opposite directions that causes horizontal movement along a fault plane
seismic waves
vibrations of the ground produced during an earthquake
3 types of seismic waves
primary, secondary, surface
primary waves
seismic wave that squeezes and pushes rock in the same direction that the wave travels
aka p wave
travel thru solids liquids and gasses
first waves felt in an earthquake
