Deep Earth & Crustal Layers
This term refers to the earth's thin outer layer made of solid rock.
What is the crust?
This is the point on the earth's surface directly above where an earthquake begins.
What is the epicenter?
Form when a magma chamber empties and collapses, creating a giant bowl-shaped crater.
What is a caldera?
This type of fold occurs when rocks buckle upward into an arch-like structure.
What is an anticline?
This volcano type consists of alternating layers of lava and cinders.
What is a composite volcano (or stratovolcano)?
This boundary marks the region where rock density changes at the bottom of the crust.
What is the Moho?
These fastest-traveling seismic waves move in a rhythmic push-pull motion.
What are P waves (or Primary waves)?
This term describes lava that hardens into a smooth or ropy surface.
What is pahoehoe?
This fault forms when rocks along one side of a fracture move vertically past stationary rock.
What is a normal fault?
Broad, gently sloping volcanoes built up by flow after flow of highly fluid lava?
What is a shield volcano?
This layer of the central earth is believed to be solid iron or nickel due to extreme pressure.
What is the inner core?
This building system uses isolators as movable stilts to absorb seismic energy beneath a foundation.
What is a base-isolated system?
This superheated avalanche of gas and volcanic ash travels swiftly down a volcanic slope.
What is a pyroclastic flow?
This fault forms when rocks along one side of a fracture move horizontally past stationary rock.
What is a strike-slip fault?
A sheet-like mass of igneous rock formed when magma hardens in a vertical crack.
What is a dike?
This element is the most abundant in the earth's crust, making up about 47% of its weight.
What is oxygen?
About 80% of all earthquakes occur in this active zone bordering the Pacific Ocean.
What is the circum-Pacific belt (or Ring of Fire)?
Volcanic ejecta larger than 64 mm that forms when lava is thrown into the air in a liquid state and hardens before hitting the ground.
What are volcanic bombs?
These mountains form when molten rock is forced beneath an overlying rock layer, bulging it upward without erupting.
What are domed mountains?
Formed when magma squeezes horizontally between two rock layers.
What is a sill?
Tectonic plates float on this layer of plastic rock located in the lower portion of the upper mantle.
What is the asthenosphere?
This theory explains how rocks on either side of a fault spring back to an unbent position after straining.
What is the elastic rebound theory?
High amounts of this characteristic in magma can lead to violent eruptions due to how thick the magma becomes.
What is viscosity?
This type of mountain range forms along a fault when rock on one side is forced upward while the other side sinks.
What are fault-block mountains?
This massive, dome-like igneous intrusion forms when stiff magma bulges overlying rock layers upward, forming structures like the Black Hills.
What is a laccolith?