San Andreas Fault - Getting Ready For the Big One


The San Andreas Fault runs through California and is one of the most important earthquake lines in the world. Geologists now predict that a major earthquake, the so-called "Big One" will occur somewhere along that line soon.

While the northern part of the fault has been hit by earthquakes several times, the last big tremor in the southern section of the San Andreas Fault happened in 1857, when a magnitude 7.9 earthquake hit the mountains near Los Angeles. Scientists say that so much tension lies in the rock formations of the southern part of the fault that the "Big One" may hit the area soon.

The Oakland Bay area, which lies almost directly above the San Andreas Fault has been hit by major earthquakes more often.  In 1906, a 7.8 earthquake hit San Francisco. It destroyed large parts of the city and killed 3,000 people. In 1989 another strong earthquake with a magnitude of 6.9 occurred south of San Francisco.

The San Andreas Fault separates two large geological plates - the Pacific Plate and the North American Plate. Because continents on earth are in steady movement, the two plates are moving past each other at a rate of about 2 inches (5 cm) per year. At some point tension inside the earth's crust will get too big and energy will be released. While there is no way of forecasting when an earthquake will hit a region, geologists think there is a good chance that a tremor with a magnitude of 7 or 8 is will hit southern California  sometime in the near future.



An abrupt movement along the plates may even trigger a series of movements throughout the area. California's largest city, Los Angeles, is only 30 miles away from the fault and may suffer severe damage.

Studies show that a major earthquake can produce damage of up to $200 billion dollars and lead to over 2,000 deaths.



Related Topics



  • abrupt = sudden
  • billion = a thousand  million
  • damage = when harm is done to something or someone
  • destroy = to damage completely
  • earthquake = a sudden shake or movement in the earth's crust; it sometimes causes a lot of damage on the surface and may lead to the death of people
  • fault = a crack in the earth's surface that separates two plates
  • forecast = to say when something will happen
  • geological plate = one of a few large sheets of rock that form the earth's surface
  • geologist = person who studies rock formations on earth
  • magnitude = the size by which an earthquake is measured
  • major = very big
  • near future = soon
  • occur = happen
  • predict = say that something will happen in the future
  • rate = speed
  • release = to set free
  • rock formation = the layers of rock that have formed over millions of years
  • scientist = person who is trained in science and works in a lab
  • separate = divide, split into two parts
  • series = here: more than one
  • several =some, a few
  • severe = very much
  • steady = here: something that happens slowly but constantly
  • studies = work that is done to find out more about a special subject
  • tension = here: being tight and ready to break
  • tremor = earthquake
  • trigger = an event that causes other , mostly bad, things to start