Two earthquakes were detected in Southern California by the Caltech seismology laboratory in Pasadena. There were no reports of damage or injuries. A Caltech spokesman said one quake, measuring 3.2 on the Richter scale, was centered five miles east-northeast of Castaic. The other measured 3.4 and was centered 15 miles north-northwest of Palm Springs. It was an aftershock of a July 8 quake that caused some property damage in and around Palm Springs, the spokesman said.