The Northridge earthquake--magnitude 6.8--caused 60 deaths and billions of dollars in property damage. Immediately after the earthquake, the rumor began to spread that seismologists at the California Institute of Technology had predicted an even larger earthquake. Caltech's response was that "Caltech cannot release predictions since it is impossible to predict earthquakes."
The vast majority of the world's seismologists think that earthquakes cannot be reliably and accurately predicted.
Despite great progress in seismological research, no physical law or mathematical formula now exists for reliably predicting the time, place and size of an earthquake.
In order to predict earthquakes, one would have to find a precursory phenomenon that always occurs before a large earthquake but never occurs otherwise. Seismologists throughout the world have searched for such a precursor for more than 100 years but their attempts have failed.
Small earthquakes occur continually but relieve only a negligible portion of the accumulated strain energy. Occasionally one of these small earthquakes will trigger a chain reaction--an avalanche of small earthquakes occurring within a few seconds--that we perceive as a single large earthquake. But since large earthquakes and small earthquakes both start in the same way--as a small earthquake--there are no scientific grounds for believing that large earthquakes are preceded by unique precursory phenomena that would allow them to be predicted.
After a large earthquake, there frequently are reports of precursors, such as changes in the water level of wells or anomalous animal behavior. Even if such reports were accurate, these phenomena have no established link with the onset of earthquakes. Sometimes there are more credible observations, such as reports of foreshocks. Unfortunately, foreshocks are just like any other small earthquake. They can only be identified as foreshocks after the main shock has occurred.
The difficulty of predicting earthquakes is further underscored by the Parkfield Earthquake Prediction Experiment on the San Andreas Fault. Several predictions have been issued, but all have been false alarms. Meanwhile, large earthquakes have occurred in Landers and Northridge.
