EARTHQUAKES

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EARTHQUAKES

• Part one

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KEY IDEAS

• -stresses on earths crust produce compression,
  tension, and shearing in rock.
• -faults are cracks in earths crust that result
  from stress
• -faulting and folding of the crust cause
  mountains and other features to form on the
  surface.

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KEY TERMS

• EARTHQUAKES-shaking and trembling that results
  from the movement of rock beneath the surface of
  the earth
• STRESS-force that acts on rock to change its
  shape or volume
• FAULT-break in the crust where slabs of crust
  slip past each other
• COMMPRESSION-squeezes rock until it folds or
  breaks

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KEY IDEAS

• -as seismic waves travel through the earth, they
  carry the energy of an earthquake from the focus
  to the surface.
• earthquakes produce two types of seismic waves, P
  waves and S waves that travel out in all
  directions from the focus of an earthquake
• -today the moment magnitude scale is used to
  determine the magnitude of an earthquake. Other
  scales that geologists have used to rate
  earthquakes include the Mercalli scale and the
  Richter scale.

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EARTHQUAKES!

• Part two!.

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KEY TERMS

• focus-point beneath earths surface where rock
  that is under stress breaks triggering an
  earthquake
• P waves-waves that compress and expand the ground
  like an accordion
• S waves-waves that shake the ground back and
  forth
• magnitude-measurement of earthquake strength
  based on seismic waves and movement along faults
• Mercalli scale-developed to rate earthquakes
  according to their intensity
• Richter scale-rating of the size of seismic waves
  as measured by a particular type of mechanical
  seismograph
• surface waves-produce severe ground movements
• seismic waves-carry the energy of an earthquake
  away from the focus through earths interior and
  across the surface

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EARTHQUAKES PART THREE

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KEY IDAES

• -earthquakes can damage structures through
  tsunamis, landslides or avalanches, and shaking
  or liquefaction of the ground.
• -new buildings can be designed to withstand
  earthquakes old buildings can be modified to
  make them more earthquake resistant.
• -for personal safety indoors during an
  earthquake, drop, cover, And hold under a desk or
  table, or against an interior wall

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KEY TERMS

• -liquefaction-occurs when an earthquakes violent
  shaking suddenly turns loose soft soil into
  liquid mud
• -aftershock-earthquake that occurs after a larger
  earthquake in the same area

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What to do before an earthquake

• Make sure that you have a plan in case one
  strikes
• Have an emergency kit ready
• Stay indoors if you know that an earthquake is
  going to happen soon

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What to do during an earthquake

• Stay indoors
• Drop, cover, And hold under a desk or table, or
  against an interior wall.

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What to do after an earthquake

• Expect aftershocks
• Listen to a battery-operated radio or television.
  Listen for the latest emergency information
• Use the telephone only for emergency calls.
• Open cabinets cautiously. Beware of objects that
  can fall off shelves.
• Stay away from damaged areas.
• Help injured or trapped people.

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Earthquake in southern Chile

• On May 22, 1960, the largest global earthquake
  recorded this century occurred along the coast of
  Southern Chile.
• centered about 480 miles south-west of Santiago
  and just off the coast of Valdivia.
• The earthquake ruptured nearly a 1,000 miles of
  the prominent Southern Chile subduction zone
• Severe shaking lasted for several minutes as the
  fault rupture proceeded both north and south from
  the focal point.
• Buildings toppled, soft coastal sediments
  liquefied, landslide swept down mountain slopes,
  and cliff fronts calved-off into the ocean.

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Earthquake in southern Chile

• 2,300 people were killed.
• Hardest hit were areas around soft sediments
  where substantial ground settlements occurred.
• The earthquake produced an enormous tsunami which
  impacted the entire Pacific rim
• Wave heights along portions of the Chilean and
  Peruvian coasts were in excess of 25 m (82 ft.)
  and literally swept low-lying beach fronts clean
  of all vegetation and construction.
• A robust aftershock lasted for years and produced
  dozens of earthquakes in the M 5.0 range.