Chapter over earthquakes-Holt Sci. 7 Flashcards
(21 cards)
What is seismology?
The study of earthquakes
Who is a seismologist?
Scientist who studies earthquakes
What is an earthquake?
A vibration of the earth that is produced by the rapid release of energy
What is a fault?
A break in the earth’s crust along which blocks of the crust slide relative to one another.
What is elastic rebound?
The sudden return of elastically deformed rock to its undeformed shape.
About how many earthquakes occur each year worldwide?
1 million
About what percent of earthquakes are large enough to be felt?
10 Percent
Where do earthquakes occur and what happens to the rocks where these occur?
Along faults. Rocks break and move along surfaces.
What is an instrument used to record and study earthquakes?
Seismograph.
Elastic rebound occurs when more stress is applied than what?
The rock can handle.
Energy is _________ during elastic rebound.
released
Energy travels as _______waves which causes earthquakes.
seismic waves
Which type of fault is it where tension pulls apart rocks? Along what type of boundaries does it occur?
Normal fault. Occurs at divergent boundaries.
Which type of fault is it where compression pushes on rock from opposite directions? Along what type of boundaries does it occur?
Reverse fault. Occurs at convergent boundaries.
Which type of fault is it where rocks on either side of the fault move past each other? What is it caused by? Along what type boundaries does it occur?
Strike-slip fault. Caused by shearing. Occurs at transform boundaries.
What are the three types of seismic waves?
Primary waves, Secondary Waves, and surface waves.
What are primary waves?
Push-pull waves/ p-waves. These are the fastest and the first to register on seismograph.
Where do primary waves travel?
Through the interior of the earth.
What are secondary waves?
Shake-shear waves, s-waves. These are the second fastest; They travel in a side to side motion.
Where do secondary waves travel?
They travel through the interior of the earth.
What are surface waves?
L-waves. They produce a rolling or swaying motion, These do the most damage. They are the last to reach the seismograph.
