Earthquakes are one of the more dramatic earth events. The life-styles of people living in earthquake prone areas are affected by these unpredictable and uncontrollable forces. For centuries, mankind has tried to predict earthquakes by identifying obser vable earth events that correlated to earthquakes. In this investigation the possible relationship between tidal stresses and earthquakes is examined, using the hypothesis that the effect of the tides is insignificant in determining the frequency of earthquakes. Tidal stresses on the earth result from the gravitational and centrifugal forces between the earth, sun, and moon.
Tidal stresses reach maximum when the earth, sun, and moon are aligned.
This occurs during the full and new moon. We have the minimum tidal stresses when the Moon and Sun are at right angles to each other. Periods of full and new moon are used to indicate the period of highest tidal stresses . The constant movement of plates on the earth's surface causes stresses to build up where these plates come together. Most earthquakes occur along faultlines at major plate boundaries, such as the San Andreas Fault.