Chapter 6 Vocabulary Flashcards
Earthquake
Series of low frequency shock waves (like sound waves), traveling through the earth.
Seismometer
An instrument that measures earth waves.
Stress
A measure of force exerted within an object.
There are three main kinds of stress:
Compression - stepping on an empty can
Tension- pulling on a rope in tug of war
Shear - forces acting in opposite directions on different parts of the same object. This stress produces earthquakes. Example - press sideways on a block of jello, shear stress in middle of jello
Divergent boundaries
Spreading zones along some plate margins. The plate sections are moving apart, or diverging.
Convergent boundaries
Plates are moving toward each other or converging.
Transform boundaries
Places where plates slide past each other in opposite directions along long cracks in the crust.
Fault
Occurs when the sections of rock on opposite sides of the crack move relative to each other.
Focus
The actual center of an underground earthquake
Epicenter
Point on the earths surface directly above the place inside the earth where the earthquake actually happened
Richter scale
Used to report the energy or strength of an earthquake
Magnitude
A measure of the energy released by an earthquake
Intensity
A measure of the damage caused by an earthquake
Tsunami
A far reaching devastating water wave caused by an earthquake
Strike
The direction of a fault
Dip-slip fault
A fault’s motion that is parallel to its dip (up and down).
2 kinds of dip- slip faults:
Normal fault - when the block above the fault surface drops in relation to the block under the fault
Reverse fault - when the upper block rose in relation to the lower block. If the dip is less than a 45 degree angle it is a Thrust Fault
