The largest recorded earthquake in the United States was a magnitude 9.2
that struck Prince William Sound, Alaska on Good Friday, March 28, 1964
Seismology
The largest recorded earthquake in the world was a magnitude 9.5 (Mw) in Chile on May 22, 1960.
 Rocks will bend and stretch up to a limit
undergoing elastic deformation.
 A fault is created when the rock finally breaks.
 An earthquake is the vibrations produced by
the breaking of the rock.
Types of Faults
Normal Faults
 Tensional forces pull the rock apart.
 Rock above the fault surface moves
downward compared to the rock
below the fault surface.
The average rate of motion across the San Andreas
Fault Zone during the past 3 million years is 56 mm/yr
(2 in/yr). This is about the same rate at which your
fingernails grow. Assuming this rate continues,
scientists project that Los Angeles and San Francisco
will be adjacent to one another in approximately 15
million years.
Reverse Fault
 Compression forces squeeze the
rock.
 Rock above the fault surface moves
upward and over the rock below the
fault surface.
It is estimated that there are 500,000 detectable
earthquakes in the world each year. 100,000 of those can
be felt, and 100 of them cause damage.
Strike-Slip Fault
 Shear forces tear the rock.
 Rocks on either side of the fault are
moving past each other without
upward or downward movement.
From 1975-1995 there were only four states that
did not have any earthquakes. They were:
Florida, Iowa, North Dakota, and Wisconsin.
Seismic Waves
 Waves generated by earthquakes that travel
through the Earth.
Origin of Seismic Waves
Focus- the point where the energy is first released.
 Below the surface along the fault.
Epicenter- point on the surface of the Earth directly
above the focus
The world’s deadliest recorded
earthquake occurred in 1556 in
central China. It struck a region
where most people lived in caves
carved from soft rock. These
dwellings collapsed during the
earthquake, killing an estimated
830,000 people. In 1976 another
deadly earthquake struck in
Tangshan, China, where more
than 250,000 people were killed.
• Particles in the rock move back and forth in the same
direction the wave is traveling.
• Fastest seismic waves
Types of
Seismic
Waves
Primary
Waves
(PWaves)
Secondary Waves (S-Waves)
 Particles in the rock move up and down at
right angles to the direction of wave travel.
Alaska is the most
earthquake-prone
state and one of the
most seismically
active regions in the
world. Alaska
experiences a
magnitude 7
earthquake almost
every year, and a
magnitude 8 or
greater earthquake
on average every 14
years.
Surface Waves (L-Waves)
 Particles in the rock move in a backward,
rolling motion and a side-to-side, swaying
motion.
 Causes the most damage.
 Originate from the epicenter.
When the Chilean
earthquake occurred
in
1960, seismographs
recorded seismic
waves that traveled
all around the Earth.
These seismic waves
shook the entire earth
for many days! This
phenomenon is called
the free oscillation of
the Earth.
How many earthquakes
happen every month? Day?
Minute?
Per year: Approximately
1,000,000, including those
too small to be felt.
Per month: Approximately
80,000
Per day: Approximately
2,600
Per minute: Approximately 2
Per second: Approximately
one earthquake every 30
seconds.
Locating an Epicenter
 Seismograph
 Register the waves & record the
time that each arrived.
Seismogram
L Waves
P Waves
S Waves
1 min
Time between P & S waves = 3 minutes
Time for entire quake = 8 minutes
• Data
from three separate stations are
required to locate the epicenter of an
earthquake.
• The epicenter distance is figured out using
the time difference between the P & S waves
graph.
Magnitude
 The amount of energy released in an
earthquake.
 Richter Scale- a numeric scale used to
describe the strength (magnitude) of an
earthquake.
 Mercalli Scale- scale that describes the
amount of damage.
Liquefaction
• Wet soil can be strong most of the time,
but the shaking from an earthquake can
cause it to act like a liquid.
• This causes soil to sink into the ground
and cause things to collapse.
Tsunamis
• Under water
earthquakes cause
the water to shake
forming large
waves.
• Seismic sea waves
• Wave crests can
reach 30m in height
by the time it
reaches shore.
A tsunami is a series of ocean waves that sends surges of
water, sometimes reaching heights of over 100 feet (30.5
meters), onto land.
Most tsunamis, about 80 percent,
happen within the Pacific Ocean’s “Ring
of Fire,”
A tsunami’s trough, the low point beneath the
wave’s crest, often reaches shore first. When it
does, it produces a vacuum effect that sucks
coastal water seaward and exposes harbor
and sea floors. This retreating of sea water is
an important warning sign of a tsunami,
because the wave’s crest and its enormous
volume of water typically hit shore five minutes
or so later.
Tsunamis race across the sea at up to
500 miles (805 kilometers) an hour—
about as fast as a jet airplane. At that
pace they can cross the entire expanse
of the Pacific Ocean in less than a day.
In deep ocean, tsunami waves may appear only a
foot or so high. But as they approach shoreline
and enter shallower water they slow down and
begin to grow in energy and height. The tops of
the waves move faster than their bottoms do,
which causes them to rise precipitously.
In 2004, the Indian Ocean tsunami was caused by an earthquake
that is thought to have had the energy of 23,000 atomic bombs.
Within hours of the earthquake in 2004, killer waves radiating from
the epicenter slammed into the coastline of 11 countries, damaging
countries from east Africa to Thailand. By the end of the day, the
tsunami had already killed 150,000 people. The final death toll was
283,000.
Tsunami waves can be very long
(as much as 60 miles, or 100
kilometers) and be as far as one
hour apart. They are able to cross
entire oceans without great loss of
energy. The Indian Ocean tsunami
traveled as much as 3,000 miles
(nearly 5,000 kilometers) to Africa,
arriving with sufficient force to kill
people and destroy property.
A tsunami is not a single
wave but a series of
waves, also known as a
wave train. The first wave
in a tsunami is not
necessarily the most
destructive. Tsunamis are
not tidal waves.
Liquefaction miniature Demo:
http://www.youtube.com/watch?v=PwvvYxSZ7PI
Christchurch wheelbarrow demo :
http://www.youtube.com/watch?v=1KqlAMWMjOE
Liquefaction during an earthquake in Japan:
http://www.youtube.com/watch?v=rn3oAvmZY8k
Turkey earthquake: 5.7
http://www.youtube.com/watch?v=4dNtqjgkCts
Christchurch earthquake recap 6.3:
http://www.youtube.com/watch?v=wBq1qZWmhM&feature=relmfu
Japan mall earthquake 8.9- first part only (long drags out)
http://www.youtube.com/watch?v=VCU_gSkRhIY&feature=related
Miyako, Japan Tsunami : http://www.youtube.com/watch?v=5zfCBCq-8I&feature=relmfu
Japan carboats : http://www.youtube.com/watch?v=eUdGfplrbKU
Japan 8.9 tsunami:
http://www.youtube.com/watch?v=TRDpTEjumdo
Japan first person tsunami view:
http://www.youtube.com/watch?v=BAuWa77vYDU
What to watch for with a tsunami. 6:11 - 8:45 rest too graphic (made me cry
series) http://www.youtube.com/watch?v=PHpG1P3JwEU
Tilly Smith ABC (cut 3:14-3:31 bodies)
http://abcnews.go.com/video/playerIndex?id=6721606
Tilly Smith (young)
http://www.youtube.com/watch?v=V0s2i7Cc7wA&feature=youtu.b
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