Earthquakes can cause great physical damage and can result in large losses of life. Therefore, accurately predicting earthquakes would be very beneficial.

Short-Term Prediction: Short-term prediction refers to predicting earthquakes within a matter of hours or days. Measurement of certain physical parameters might act as indicators of possible earthquakes. Measuring the strain in rocks near faults, the rate of land uplift, and fluctuations in groundwater levels may provide signals of a possible earthquake event. Some researchers claim that strange animal behavior such as catfish swimming violently, chickens stopping laying eggs, and dogs barking for no reason may signal a coming earthquake. Unfortunately, none of these methods has been proven to be a reliable predictor of earthquakes. At the moment, accurate and reliable short-term prediction of earthquakes is not a realistic possibility.

Long-Term Prediction: Long-term prediction refers to a timeframe of years or even decades. Long-term prediction depends on historical records, patterns emerging over time, and long-term observations of rock movement and strain. These observations result in scientists being able to assign a probability for an earthquake occurring in a certain geographical area, usually within a span of several decades. The U.S. Geological Survey (USGS), for example, has predicted that the Hayward-Rogers Fault system in the San Francisco Bay area has a high probability of an upcoming earthquake. This is based on records that show that the average interval between earthquakes in this area is 140 years. Since the last earthquake in this area occurred in 1868, the USGS is predicting a high probability for another earthquake sometime within the next 30 years. Long-term prediction, because it is based on long-term patterns and observations, has had some success, and is considered to be reasonably reliable.

Learning Activity

Click here to view a seismic hazard map for the entire United States.

1. Which areas have a very high probability of an earthquake?
   
   Earthquakes are highly probable on the west coast, the California-Nevada border area, the Montana-Idaho-Wyoming corner, the southern coast of Alaska, and in Hawaii.

Click here to view magnitude 6.5 and greater earthquakes since 1978.

2. Have all the major earthquakes since 1978 occurred within these zones of very high risk?
   
   Yes, they have all occurred within zones of very high risk. The only possible exception to this might be the Idaho earthquake, but it is very close to the Montana-Idaho-Wyoming high risk corner.

Click here to zoom in on the San Francisco Bay area.

Now add in all the major fault lines.

3. What are some major cities that are either right on, or very close to major fault lines?
   
   San Francisco, San Jose, Oakland, and Santa Rosa are either right on, or very close to major fault lines.

Now add in the probability of major earthquakes before 2036 as determined by the USGS.

4. What is the probability of an earthquake in San Francisco before 2036?
   
   The probability is 21%.
5. 1. Which area has the highest probability of an earthquake?
      
      The Hayward-Rogers Creek Fault zone has the highest probability of an earthquake.
   2. What is the probability of an earthquake here?
      
      The earthquake probability is 31%.
6. What is the probability of an earthquake occurring somewhere in the San Francisco Bay area sometime before 2036?
   
   The probability is 63%.