Abstract
Earthquake occurrence is not uniform in either space or time. It seems that earthquakes have relations with each other. In cases where the difference is small in both spatial location and occurrence time between two given earthquakes, they are defined to have ’relation’. We try to calculate the degree of relationship using the Fuzzy theory. Identification of pre-shocks and aftershocks is given automatically from the relationships. We will be able to obtain important information about previous earthquake activities by using the relationships.
