The response to loading is different from that to unloading when the focal media is approaching instability. The ratio of the response rate during loading to that during unloading, called Load/Unload Response Ratio Y (LURR), could be a measure of the closeness degree to instability and is used in a new approach to earthquake prediction. Retrospective examination of some one hundred earthquake cases (from M 4 to M 8.6) indicates that for more than 80% of the examined ones, the value of Y is much higher than 1 for a period before the main shock, but the Y value always fluctuates slightly about 1 during two decades for seven stable regions, so that the parameter Y could indicate a dangerous degree of an impending earthquake. Several earthquakes occurring on the Chinese mainland in recent years as well as the Northridge California, U.S.A. earthquake (Jan. 17, 1994, M(w) 6.7) have been predicted beforehand with this method.
