Chapter 8 – Earthquakes and Volcanoes
Vocabulary
Section 1: pages 210 – 218
energy: the ability to cause change
earthquake: movement of ground that occurs when rocks inside
the Earth pass their elastic limit, break suddenly, and experience
elastic rebound
fault: fracture that occurs when rocks break and that results in
relative movement of opposing sides
seismic wave: earthquake waves, including primary, secondary,
and surface (L) waves
focus: point inside the Earth where an earthquake occurs
epicenter: point on the Earth’s surface where an earthquake
occurs, directly above the focus
seismograph: instrument used to record seismic waves
magnitude: a measure of the energy released during an
earthquake
tsunami: powerful wave caused by an earthquake located under
the ocean floor
seismic safe: describes the ability of structures to stand up against
the vibrations caused during an earthquake
Section 2: pages 219 -224
plate: a large section of Earth’s crust and rigid upper mantle that
moves around on the asthenosphere
volcano: cone-shaped hill or mountain formed when hot magma,
solids, and gas erupt on to the Earth’s surface
lava: molten rock on the Earth’s surface
shield volcano: large, broad volcano with gently sloping sides that
is formed by quiet eruptions
cinder cone volcano: relatively small volcano formed by moderate
to explosive eruptions
composite volcano: steep-sided volcano formed from alternating
layers of violent eruptions and quieter eruptions
Section 3: pages 226 - 231
asthenosphere: plastic-like layer of mantle under the lithosphere
rift: long, crack, fissure, or trough that forms between tectonic
plates moving apart at plate boundaries
hot spot: hot, molten rock forced upward from deep inside the
Earth which may cause magma to break through the Earth’s surface
and cause volcanoes; usually occurs in the middle of a plate