ARE EARTHQUAKES PREDICTABLE

The answer to the above question depends on the definition of earthqua ke prediction. We discuss several definitions and possible classificat ions of earthquake prediction methods. We also consider various measur es of prediction efficiency, review several recent examples of earthqu ake prediction, and describe the methods that can be used to verify pr ediction schemes. We conclude that an empirical search for earthquake precursors that forecast the size of an impending earthquake has been fruitless. Despite considerable effort in several countries, no statis tically rigorous validation of proposed precursory phenomena is availa ble; therefore, reported cases of precursors can be explained by rando m noise or by chance coincidence. We present evidence that earthquakes are non-linear, chaotic, scale-invariant phenomena. The most probable consequence of earthquake self-similarity is a lack of earthquake pre dictability as popularly defined, that is a forecast of a specific ind ividual earthquake. Many small earthquakes occur throughout any seismi c zone, demonstrating that the critical conditions for earthquake nucl eation are satisfied almost everywhere. Apparently, any small shock ca n grow into a large event. Thus, it is likely that an earthquake has n o preparatory stage. This sceptical view of current earthquake predict ion efforts should not be interpreted as a statement that any further attempts to mitigate the destructive effects of earthquakes are futile . The seismic-moment conservation principle, when combined with geodet ic deformation data, offers a new way to evaluate the seismic hazard, not only for tectonic plate boundaries, but also for areas of low seis micity, that is the interiors of continents. Earthquake clustering wit h a power-law temporal decay (Omori's law) can be used to estimate the rate of future earthquake ocurrence. Realtime seismology can facilita te relief efforts after large earthquakes and eventually provide an im mediate warning of severe shaking a few seconds or tens of seconds bef ore the shaking starts.