Earthquakes

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Earthquakes
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MEASURING EARTHQUAKES

• Seismograph
• records the intensity, direction, and duration
  of an earthquake.
• Richter Scale
• Measures the amplitude (intensity) of seismic
  waves
• 1 small disturbance, 9 great disturbance.
• Each increase on the scale is magnified 10 times.

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MEASURING EARTHQUAKES
Seismograph of a magnitude 9.5 earthquake
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RICHTER SCALE

• lt 3.5 ------ Generally not felt, but recorded.
• 3.5-5.4 ---- Often felt, but rarely causes
  damage.
• lt 6.0 ------ At most slight damage to
  well-designed buildings. Can cause major
  damage to poorly constructed buildings over
  small regions.
• 6.1-6.9 ---- Can be destructive in areas up to
  about 100 km across where people live.
• 7.0-7.9 ---- Major earthquake. Can cause serious
  damage over larger areas.
• 8 --------- Great earthquake. Can cause serious
  damage in areas several hundred
  kilometers across.

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QUAKE FACTS
Frequency of Occurrence of Earthquakes Based on
Observations since 1900
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Earthquakes in the past week, day, and hour
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FAMOUS EARTHQUAKES

• 1906 San Francisco
• Most damaging in U.S. history
• Magnitude 7.8
• 3000 people died

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FAMOUS EARTHQUAKES

• 1960 - Chile
• Largest in world
• Magnitude 9.5
• Large tsunami created

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On May 22, 1960, at 1911 GMT, an earthquake
occurred off the coast of South Central Chile. A
Pacific-wide tsunami was triggered by the
earthquake, which had a surface-wave magnitude of
8.6, an epicenter of 39.5 S, 74.5 W, and a
focal depth of 33 km. The number of fatalities
associated with both the tsunami and the
earthquake has been estimated to be between 490
to 2,290. Damage cost estimates were over a half
billion dollars.
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FAMOUS EARTHQUAKES

• 1964 Alaska
• Largest in the U.S.
• Magnitude 9.2

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Close-up of Government Hill elementary school,
which was destroyed by the Government Hill
landslide. Anchorage, Alaska.
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The 6-story high Four Seasons apartment building
in Anchorage was completely destroyed
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1995 Great Hanshin Earthquake aka Kobe
Earthquake Magnitude 6.9
One of the most devastating earthquakes ever to
hit Japan more than 5,500 were killed and over
26,000 injured. The economic loss has been
estimated at about US 200 billion.
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Most Destructive Known Earthquakes on Record in
the World

• Date Place Magnitude Deaths
• 1556  01 23 China, Shensi 8 830000
• 2004  12 26 Sumatra 9.1 283106
• 2005 10 08 Pakistan 7.6 80361

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Types of Faults

• There are 3 types of faults.
• Normal
• Reverse
• Strike slip (transverse)

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Normal Fault
A normal fault drops rock on one side of the
fault down relative to the other side.
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Reverse Fault
Along a reverse fault one side is pushed up
relative to rock on the other side.
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Strike-Slip Fault
There is horizontal movement not up or down