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Science Notes
Earthquakes
Earthquakes – one of nature’s most violent
phenomena. Earthquakes happen when
plates suddenly break or shift under stress.
The deadliest earthquake ever occurred in
China in 1557.
Most earthquakes occur along faults. Faults
occur where plates meet.
Intraplate quakes happen when stress builds
up and the earth’s crust is stretched or
squeezed together until it rips.
The largest quake belt is where plates
carrying the Pacific Ocean come into contact
with plates carrying the continents
surrounding the Pacific. This belt includes
the most active zone in the United States.
(California, Hawaii, and Alaska)
The earth’s plates are constantly moving and
interacting in a process called plate
tectonics. Usually the plates move slowly,
but occasionally stress builds up and is
released suddenly in seismic waves. This
causes the earthquake.
Four types of faults:
1. Normal fault – common through the
world – Plate boundaries pull apart
and one side of the fault slips down.
2. Reverse fault – Occurs where plates
are colliding and one side of the fault
is pushed up and over the other.
(Thrust fault/reverse fault)
3. Strike-slip fault – plates meet evenly
and slide against each other
horizontally. The San Andreas Fault
in California is a strike-slip fault.
4. Dip-slip fault – strike-slip faults
combined with a normal or reverse
fault. One plate moves sideways, and
one plate moves downward.
A fault can be a few inches or hundreds
of miles long. They can be horizontal,
vertical, or incline. Some are seen at the
Earth’s surface while others are deep
beneath the ground.
Hypocenter – the place where the
movement first occurred in the fault
Epicenter – the point on the surface
directly above the hypocenter
Seismograph – instrument used to
measure seismic waves. The resulting
pattern reveals where the quake began,
how long it lasted , and how much
energy was released.
The Richter Scale is used to assign
magnitudes to quakes. It assigns a
number based on the amplitude of its
seismic waves.
Collapsing buildings are one of the
leading causes of death during an
earthquake. Construction material,
building structure, and foundation design
are critical elements to consider when
designing buildings to withstand
earthquakes.
Ground Types
l. Bedrock – hard, solid rock – safest
place to build to avoid earthquake
damage.
2.Fault Zone – building in danger –
major rupturing along a fault and
significant displacement.
3.Landfill – soft, loose sediment – most
dangerous place during an earthquake.
Science Notes
Earthquakes
_________________ – one of nature’s most violent phenomena.
Earthquakes happen when plates suddenly ___________ or shift
under ________________.
The deadliest earthquake ever occurred in __________ in 1557.
Most earthquakes occur along _________. Faults occur where
_________________ meet.
____________________ quakes happen when stress builds up and
the earth’s crust is ____________ or squeezed together until it rips.
The largest quake belt is where plates carrying the ____________
come into _______________ with plates carrying the
__________________ surrounding the Pacific. This belt includes
the most active zone in the United States. (California, Hawaii, and
Alaska)
The earth’s plates are constantly ____________ and interacting in
a process called ___________________. Usually the plates move
slowly, but occasionally stress builds up and is released suddenly
in _____________ waves. This causes the _________________.
Four types of faults:
1.____________________ – common through the world – Plate boundaries
pull apart and one side of the fault slips down.
2._________________ – Occurs where plates are colliding and one side of
the fault is pushed up and over the other. (Thrust fault/reverse fault)
3.__________________ – plates meet evenly and slide against each other
horizontally. The San Andreas Fault in California is a strike-slip fault.
4.____________________ – strike-slip faults combined with a normal or
reverse fault. One plate moves sideways, and one plate moves downward.
A ______________ can be a few inches or hundreds of miles long.
They can be horizontal, _____________, or incline. Some are seen at
the Earth’s ____________ while others are deep beneath the
______________.
_______________ – the place where the movement first occurred in
the fault
________________ – the point on the surface directly above the
____________________
____________________ – instrument used to measure seismic waves.
The resulting pattern reveals where the quake ________, how long it
lasted, and how much ______________ was released.
The _______________ is used to assign magnitudes to quakes. It
assigns a number based on the amplitude of its __________________.
Collapsing ____________ are one of the leading causes of _________
during an earthquake. Construction material, building structure, and
foundation design are critical elements to consider when designing
buildings to withstand ___________________.
Ground Types
1._____________ – hard, solid rock – safest place to build to avoid
______________________ damage.
2. _____________________ – building in danger – major
rupturing along a fault and significant displacement.
3. _______________ – soft, loose sediment – most dangerous
place during an earthquake.