Earthquakes
Definition of earthquake
Shaking and trembling that results from the movement of rock below the Earth's surface.
Why does magma rise?
It is less dense than the surrounding rock.
Force that acts upon rock to change its shape or volume
Stress
1 fact about P waves
1. First to arrive
2. Compress and expand
3. Travels through solids and liquids
Which scale is used to measure earthquakes?
Moment magnitude Scale
What is friction's role in earthquakes?
Amount of friction on a fault line will determine how strong an earthquake is.
What is an eruption?
When pressure builds under the surface of a volcano, and magma erupts on the surface.
Vibrations that travel through Earth carrying the energy released during earthquakes
Seismic Waves
1 fact about S waves
1. Vibrate side to side and up and down
2. Shake ground back and forth
3. Can only travel through solids
What is the size of an earthquake with low friction?
Small or undetectable
What is the point beneath Earth's surface where rock breaks triggering an earthquake/
Focus
What is a quiet eruption?
1. Magma flows easily
2. Gases dissolved in magma bubble out gently
3. Low silica content - Runny
An instrument that records ground movements caused by seismic waves
Seismographs
1 fact about surface waves
1. P/S waves turn into these sometimes
2. Slower than P/S waves, but cause more severe movements
What happens to create a tsunami?
Plate movements cause the ocean floor to rise and push water out of the way.
What is the point directly above the focus on Earth's surface?
Epicenter
What is an explosive eruption?
1. Magma is thick, sticky, and builds up pressure
2. Dissolved gasses can not escape, then they explode
3. High silica content (sticky)
An earthquake's violent shaking turns loose soft soil into liquid mud
Liquefaction
3 stages of a volcano?
1. Active
2. Dormant
3. Extinct
What do you call an earthquake that occurs after a larger earthquake in the same area?
Aftershock
What is a fault?
A break in the Earth's crust where slabs of crust slip past each other.
Why are pyroclastic flows dangerous?
Temperatures above 1000 degrees and it destroys everything in their path.
Area where magma from deep within the mantle melts through the crust above it
Hotspot
Which type of soil shakes most violently during liquefaction?
Loose soil / sand
What is the difference between magma and lava?
Magma is inside of the Earth while lava is on the surface.