Environmental Studies, The Blue Planet, Chapter 6
Body Wave
A seismic wave that travels outwards from the focus, and travels through the Earth’s interior.
Surface Wave
A seismic wave that travels around the Earth’s surface.
Deformation
A change in shape.
Elastic Deformation
When a change in shape reverses when force is removed.
Elastic Energy
Energy stored in rocks.
Elastic Rebound Hypothesis
The hypothesis of earthquake formation. Some fault surfaces are rough, become locked.
Epicenter
The surface center of an earthquake.
Focus
The overall origin of an earthquake.
Fault
A break or fracture in rock.
Liquification
The sudden disturbance of liquid which turns seemingly solid ground to quicksand.
Magnitude
The measure of energy of an earthquake.
Modified Mercalli Intensity (MMI)
A scale used to quantify the magnitude of earthquakes.
Moho
Not YOLO. Mohorovicic Discontinuity. The base of the crust that separates the crust from the underlying zone of denser composition.
P-Wave
The first waves recorded by a seismograph after an earthquake.
S-Waves
The second waves recorded by a seismograph after an earthquake.
Reflection
When seismic waves are reflected by numerous bounderies inside the planet.
Refraction
When the speed of a wave changes as it passes from one medium to another, causing i to bed. (Pencil in water.)
Richter Magnitude
A measurement of the amplitude of seismic waves. Corrects for distance from the epicenter.
Seismic Discontinuities
Bounderies where the velocity of waves changes suddenly rather than smoothly.
Seismic Gaps
Places where earthquakes haven’t occurred in a long time.
Seismic Moment Magnitude
The scale used to determine the magnitude of a quake.
Seismic Wave
The vibrations caused by elastically stored energy carried out to other parts of the Earth.
Seismicity
Earthquake activity.
Seismogram
A recording made by a seismogram.
Seismograph
A machine used to record seismic waves.
Tsunami
A seismic sea wave.
Andesitic Magma
A type of magma that contains about 60% silicon and lots of dissolved gas.
Basaltic Magma
A type of magma that’s has 60% silicon and little dissolved gas. (80% of magma from all volcanoes.)
Batholith
Similar to stocks, huge plutonic bodies that are fundamental building blocks of continental crust.
Caldera
A large depression near the summit of a volcano several kilometers in diameter. Formed by collapse after eruption.
Dormant Volcano
A volcano that is dormant.
Eruption Column
What comes out of a volcano.
Extinct Volcano
A dead volcano.
Fissure Eruption
When lava reaches the surface of Earth through an elongate vent.
Hot Spot
Places lava is fed to the surface by plumes.
Plume
An upwelling mass of hot air (see: Glenn Beck) and material.
Lava
Magma that reaches the Earth’s surface.
Magma
A mixture of molten rock, minerals grains, and dissolved gas formed at high temperatures.
Partial Melt
When something melts only partially.
Pyroclast
A fragment of hot shattered magma ejected during an explosive eruption (ewwww….)
Pyroclastic Flow
A mobile mass of tephra that is denser than the atmosphere and will not rise into the air, but just flow over.
Pyroclastic Rock
Consolidated, solid tephra.
Tephra
A deposit of unconsolidated loose pyroclasts.
Rhyolitic Magma
A type of magma containing 70% silicon and the highest gas content.
Shield Volcano
A dome-shaped volcano with a small slope, formed by successive eruptions of basaltic lava.
Stratovolvano
Your typical cone-shaped volcano. Has layers of lava and tephra.
Tephra Cone
The cone that builds up around the vent of a steep volcano.
Viscosity
The property that causes a substance to resist flowing. Magma viscosity depends on composition
Volcanic Ash
The smallest tephra particles.
Volcanic Gas
Small amounts of gas dissolved in magma.
Volcano
A vent from which melted rock, solid rock debris, and gas is expelled.
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