San Andreas Fault

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San Andreas Fault
Presentation by
Zack Bick
Erin Riggs
Alicia Helton
Cara Dickerson
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What is it?

• San Andreas Fault, geological fault zone in
  California
• 800mi long and approx. 10mi deep
• Right lateral strike-slip fault
• Imperial Valley to Point Arena
• Marks the boundary between N.American and Pacific
  plates
• Movement of the plates cause earthquakes

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Surface Features

• A linear trough reveals the presence of the fault
• The fault zone is marked by distinctive landforms
• These include long straight escarpments, narrow
  ridges, and small un-drained ponds
• Stream channels characteristically jog sharply to
  the right where they cross the fault

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Brief History

• The San Andreas Fault has been dated at 29
  million years old
• The greatest recorded movement at one time was 5
  meters in the great San Francisco Earthquake of
  1906
• This measured an 8.25 on the Richter Scale

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Major Earthquakes Along the Fault

• 1906, San Francisco
• Began at 512 am, lasted 20-25 seconds and the
  aftershocks lasted 45-60 seconds
• It measured 8.25 on the Richter Scale

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1906 San Francisco Quake

• The number of deaths resulting from the quake and
  the fire following the quake was 3,000
• The total number of injuries was 225,000
• The property damage that occurred was estimated
  at 400million in 1906 dollars.

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1952 Kern County Quake

• Occurred on July 21, at 5 am
• The quake measured 7.5 on the Richter Scale
• The quake was felt from Reno, Nevada to San
  Diego, California

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1952 Quake

• The quake came as a surprise to geologists
• The quake was responsible for
• 12 deaths
• 18 injuries
• 50 million in property damage

9
1989 Loma Prieta Quake

• Occurred October 17th, at 5 pm
• The magnitude was estimated 7.1 on the Richter
  Scale
• The quake did not come as a surprise to geologists

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1989 Quake

• The quake caused damage in San Francisco and
  Oakland
• The 1989 earthquake caused
• 7 billion in damage
• 12,000 displaced people
• 3,757 injuries and 67 deaths

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New Designs and Construction of Buildings in
Earthquake Prone Areas

• Buildings, homes, bridges and overpasses will be
  built to withstand strong shaking
• Some cities have programs to tear down unstable
  buildings or homes
• Automatic shut off of gas lines when the P-wave
  hits to limit fire hazards

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Selective Use of Land

• Places not to build homes or buildings
• Ground failure areas of liquefaction
• Landslide prone areas

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Accurate Prediction of Earthquakes(A Work In
Progress)

• China has been the only country who has predicted
  an earthquake nine hours before, in which they
  saved lives
• However, the next quake they had came unexpected
• In Tokyo, Japan they are hard away at work trying
  to learn how to successfully predict earthquakes
• Other geologists around the world are also
  working to find an answer to predict the quakes

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Earthquake Probability

• Research conducted since the 1989 quake helped
  USGS and other scientists conclude
• 70 probability of at least one magnitude 6.7 or
  greater quake
• 21 probability of that 70 is on the San Andreas
  Fault
• The quake might strike the San Francisco Bay
  region before 2030
• Major quakes may occur in any part of this region
  
• Communities in the Bay Area region continue to
  prepare for earthquakes

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Earthquake Odds

• Rates of large earthquakes in the San Francisco
  have dropped after the Great 1906 Earthquake.
• San Andreas Fault slipped so much over such a
  great length in that quake that the strain was
  reduced on most faults throughout the region.
• Strain has been slowly building up again.
• However, level of seismic activity has not yet
  reached that of the late 1800's.

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In Conclusion, weve learned

• The geography of the San Andreas Fault
• A few of the major quakes on the fault
• What everyone can do to help reduce the risk of
  disaster when a quake hits
• Probability of the next big earthquake