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25 terms

4th Grade Unit C Ch. 1 Earthquakes and Volcanoes

STUDY
PLAY
ocean-floor crust
Some volcanoes form new ___________ as plates move apart and magma rises to the surface of the crust.
inner core
Earth's ________ is its hottest layer.
measure
Scientist can __________ earthquakes by using seismographs, the Mercalli scale, and the Richter scale.
fault
California has more than 20,000 earthquakes each year, because there is a large ___________ running through the state.
do not
All eruptions _______ form the same kinds of volcanic mountains because the shape of a volcano depends on what type of materials it erupts. There are different eruptions for different volcanoes.
mantle
Earth's plates move very slowly across Earth's surface on a thin layer of partly melted _________.
layers
The inner core, the outer core, the mantle, and the crust are the _______ of the Earth.
magnitude
The 1964 Alaska earthquake released more energy than the 1989 California earthquake as measured by the ____________ (size of waves) and the intensity using a Richter scale.
mountains
If Earth's plates stopped moving, then the Earth's core would cool and no new mountains would form. Then rain would erode the Earth's surface until it was flat and covered with water.
Ring of Fire
The _____________ is an area with frequent earthquakes and volcanic eruptions that circles the Pacific Ocean.
focus
_________ is the point underground where the movement of an earthquake first took place.
magma
________ is the melted rock inside the Earth.
lava
________ is the melted rock that reaches Earth's surface.
epicenter
________ is the point on the surface of Earth that is right above the focus of an earthquake.
vent
__________ is the rocky tube in a volcano through which magma rises toward the surface.
seismograph
_________ is an instrument that records earthquake waves.
magma chamber
_________ is an underground pool below a volcano that holds magma.
volcano
________ is a mountain that forms when red-hot melted rock flows through a crack onto Earth's surface.
crater
________ is a large basin formed at the top of a volcano when the top falls in on itself.
crust
_______ is the Earth's outer layer and includes the rock of the ocean floor and large areas of land.
mantle
________ is the thickest layer of Earth and is found just below the crust.
fault
_______ is a break in the Earth's crust along which rocks move.
earthquake
_______ is a vibration, or shaking, of the Earth's crust.
plate
_______ is a continent-sized slab of Earth's crust and upper mantle.
core
_______ is the dense center of the Earth and is a ball made mostly of two metals (iron and nickel).