San Ramon -- Quakes in the San Ramon area made Thanksgiving an exciting one, with at least five temblors reported Thursday, according to the United States Geological Survey.

The USGS reports that a 2.8-magnitude earthquake occurred at 2:39 p.m. Thursday about 4 miles southeast of San Ramon. Another small temblor, measuring 1.3 on the Richter scale, transpired about 2 kilometers northeast of Pleasanton at 1:14 p.m. At 6:52 a.m. a small 1.2 earthquake occurred about 5 kilometers north of Dublin.

Three small quakes shook San Ramon between 2:52 a.m. and 2:58 a.m. that measured between 1.5 and 2.3 on the Richter Scale. Each early-morning temblor occurred near San Ramon.

Since Sunday, residents have been on alert with earthquake officials saying the cluster of seismic activity is centered on a minor fault that runs perpendicular to the Calaveras and Concord faults.

The Calaveras fault breaks off from the San Andreas fault near Hollister and Peters near San Ramon. The Concord fault is a few kilometers to the east.

Scientists say they cannot predict how long the swarm of quakes will last.