An earthquake with a preliminary magnitude of 3.3  shook eastern San Diego County, and was felt as far away as Riverside Sunday morning.

      "We feel them out here all the time, but not like this one," said  Cheryl Gillott, a state parks worker in Ocotillo Wells. "It was pretty big." 

      The 9:04 a.m. temblor was centered about 16 miles east-southeast of  Julian, or 16 miles due south of Borrego Springs. That spot would be in the  isolated desert mountains about 75 miles southeast of downtown Riverside.

      Persons scattered around eastern San Diego County reported feeling  shaking from the quake, which was centered at a depth of about 3 miles below  the surface. It was also reportedly felt in the cities of San Diego and  Riverside.

      Gillott, an employee at the Ocotillo Wells State Vehicular Recreation  Area Discovery Center, described the quake as having a rolling, as opposed to  jolting, motion.

      Automated seismographs and computers originally calculated the quake to  be magnitude 3.3, but the data was reviewed by seismologists and the magnitude  was changed to 3.4.