A mild earthquake shook the eastern reaches of San Diego County today, but there were no reported injuries or damage.

The 3.9-magnitude temblor, which was centered about four miles west of Borrego Springs, struck at 10:55 a.m., according to the U.S. Geological Survey and Caltech seismologists.

The county Sheriff's Department received no calls, emergency or otherwise, about the shaker, a dispatcher said.

Rich Caldwell, owner of the Borrego Valley Inn, said the quake was "quite noticeable" but caused no apparent harm to the lodge or to his nearby home, which he checked out after feeling the ground tremor.

An apparent aftershock followed about 20 minutes after the initial temblor, Caldwell said.