The San Andreas Fault runs through California and is one of the earthquake lines in the world. Geologists now 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 7.9 earthquake hit the mountains near Los Angeles. Scientists say that so much tension lies in the rock 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 large parts of the city and killed 3,000 people. In 1989 another strong earthquake with a magnitude of 6.9 south of San Francisco.

The San Andreas Fault separates two large geological - the Pacific Plate and the North American Plate. Because continents on Earth are in steady , 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 will be released. While there is no way of forecasting when an earthquake will hit a region, think there is a good chance that a tremor with a magnitude of 7 or 8 is will hit southern California sometime in the future.

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

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