Earthquakes vocab

Stress

A force that acts on rock to change its shape or volume

Tension

When 2 plates move away from each other, creating a normal fault(divergent)

Compression

squeezing of rocks, 1 plate pushing against another. Stress force squeezes the rock until it folds or breaks.

Shearing

Pushes 2 rocks in opposite directions. Slip past each other (transform)

Normal faults

Divergent plates, caused by tension in the earth’s crust.

Reverse fault

 Compression causes rock to push together resulting in blocks to move in the reverse direction of a normal fault.

Strike and slip fault

Shearing forces of 2 rocks slipping past each other sideways(lateral movement), with little up or down motion.

Thrust fault

Caused by major compressional forces pushing the hanging wall completely on top of the footwall

Hanging wall

Block of rock that is above or over the fault

Footwall

Block of rock that is underneath the fault.

Rift valley

a lowland region that forms where Earth's tectonic plates move apart.

Fault block mountains

Tension force pulls rock apart causing normal faults. Two normal faults cut through a block of rock, the hanging wall between each slips downward, the rock moves upward.

Plateau

Large area of flat land elevated high above sea level that forms when forces in the earth’s crust push up a large, flat, block of rock, which consists of many, flat layers.

Mountains

a landform that rises significantly above the surrounding area, must be at least 300 meters. 

Anticline

A fold in the rock that bends upward into an arch

Sycline

A fold in the rock that bends downward to form a V shape

Earthquakes

 The vibration of the earth produced by the rapid release of energy; sudden movement of the Earth’s crust.  

Epicenter

The point on the earth’s surface directly above the focus

Focus

the point underground where the release of stress is located,where the earthquake starts.

Aftershock

An earthquake that occurs after a larger earthquake in the same area

Liquidification

Earthquake’s violent shaking suddenly turns loose, soft soil into a liquid    

Seismic waves

vibrations that travel through Earth carrying energy released by earthquake 

P wave

Primary wave, compresses and expands;has the greatest velocity. It can travel through solid, liquid, and gas.

S wave

Secondary wave, vibrates from side to side or up and down. Slower then p waves and does not move through liquid.

L wave

Surface waves, slowest wave. Compresses and expands in the ground, similar to waves. Causes the most damage.

Deformation

any changes in the shape or size of an object due to an applied force

Richter scale

 Rating an earthquake’s magnitude based upon the size of the earthquake’s seismic waves[1-10] 

Modified mercalli scale

Rates earthquakes according to the level of damage at a given scale, based on peoples observation of earthquakes.

Moment magnitude scale

Rates the total energy an earthquake releases,each 1 point increase in magnitude represents the release of roughly 32x’s more energy.

Seismograph

An instrument that record and measures an earthquake’s seismic waves

Ring of fire

Where many of the world's earthquakes occur in a vast area of geological activity.

Tsunami

When an earthquake jolts the ocean floor, plate movement causes the ocean floor to rise slightly and push water out of its way