Earthquakes Flashcards
(22 cards)
What type of stress forms reverse faults? What happens to the hanging wall?
Compression; the hanging wall moves up relative to the footwall
What type of stress forms strike-slip fault? What happens to the hanging wall?
shearing; There is no hangwall or footwall since there is no vertical movement.
What is stress?
Stress is a force that can push or pull rock to change its shape or volume.
The more stress on a rock, the_
more energy gets stored in that rock
What happens once the stress becomes stronger than the forces holding the rock together?
The rock will shatter. That is what causes an earthquake to form.
What is tension?
It’s is the force that pulls on the crust, causing it to get thinner in the middle.
What is compression?
The force that pushes the crust together, causing it to either fold or break.
What is shearing?
The force that pushes rock in two opposite directions causing it to bend and break.
What type of stress forms at normal faults? The hanging wall moves ____ relative to the foot wall.
Tension; down
What are anticlines and synclines?
An anticline is an upward fold in crust and synclines are downward folds in crust.
What are folded mountains?
They are the wrinkles of Earth’s crust that are usually caused by compression.
What are fault-block mountains?
It’s when two or more normal faults lie next together, it will create new areas of higher elevation (mountains) next to areas of low elevation (valleys).
What are plateaus?
It’s when a big area of flat land gets pushed up in one block, which usually occurs due to compression stress.
What is an earthquake?
vibrations created when rocks along a fault line break in response to stress
Explain the difference between the focus and the epicenter.
The focus is beneath the ground while the epicenter is above.
What is a seismic wave, and what determines their speed and path.
Seismic waves are energy waves that travel through the earth in all directions away from the earthquake. The speed and the path is affected by the materials through which the waves pass through.
What is a P-wave?
It travels the fastest and arrives first. They travel through both solid as and liquids, which causes the least damage
What is an S-wave?
It travels second fastest and arrives second. It vibrates from side to side or up and down. They cannot travel through liquids.
What is a surface wave?
They are created when P and S waves combine and reach the surface and interact. They travel the slowest and arrive last. They also vibrate in circular motions.
What is the modified Mercalli Scale and how does it measure earthquakes? When is this useful?
It is a scale created in the 1200’s to rank the intensity of an earthquake based on observations that were made by people who experienced the earthquake.; It’s useful by describing how an earthquake was experienced or other sophisticated measuring techniques.
What is the Richter scale, and how does it measure earthquakes? When is this useful?
The Richter scale is another scale that measures earthquakes by using Magnitude - a single number that scientists assign to an earthquake based on the amount of shaking measured by a seismograph.; Rates small, local earthquakes but is not very accurate for large or very distant earthquakes.
What is the Moment Magnitude Scale and how does it measure earthquakes? When is this useful?
It rates the magnitude of an earthquake based on the total amount of energy released.; All the time.
