A 3.7-magnitude earthquake struck just south of Pleasanton shortly before 8:30 p.m. Tuesday night, followed by two smaller tremblors in the same area, the U.S. Geological Survey reported.
The first was centered two miles north-northeast of Sunol and three miles south of Pleasanton. It was reported as having a depth of 5 miles.
About two hours later, according to the USGS, two smaller eaarthquakes, each with 2.1-magnitudes, occurred at 11:18 p.m. and 11:27 p.m. The earlier one had a depth of about 5.2 miles and was centered about 3 miles north,northeast of Sunol. The second was recorded by the USGS at 11:27 p.m. and had a depth of about 4.3 miles. Its epicenter was 8 miles south southeast of Sunol.
According to the USGS, the first and larger earthquake was centered two miles north-northeast of Sunol and three miles
south of Pleasanton. It was reported as having a depth of 5 miles.
Officials from the Livermore-Pleasanton Fire Department and the Pleasanton Police Department said there were no reports of injury or damage, just some curious callers wondering if there was an earthquake.
The quakes occurred just four days before the Bay Area observes the 20th anniversary of the Loma Prieta earthquake, which hit on Oct. 17, 1989 with 6.9 magnitude force and severely damaged the San Francisco and Monterey Bay regions.
Ironically enough considering Tuesday's temblor, more than 810,000 Bay Area residents, including more than 201,000 in Alameda County, will participate in the largest earthquake drill ever on Thursday.
Modeled after last year's program in Southern California that had more than 5 million participants, the Great California Shakeout marks the Loma Prieta anniversary. Students and staff at Pleasanton schools and the district offices are said to be participating at that time with duck-and-cover and evacuation drills, similar to those that schools are required to do throughout the year.
Genevieve Pastor-Cohen with the Livermore-Pleasanton Fire Department said each station is also planning to act as if there were an earthquake happening.
"At each station they will do the drop, cover and hold, pull equipment out of each station and do a mock structural assessment," she said. "They will go through normal emergency procedures and do a simulation of what they would do in a neighborhood."
They have also encouraged CERT (Community Emergency Response Teams) graduates and neighborhood watch groups to participate. Even if they're in the car at 10:15 a.m., Pastor-Cohen said people should pull over to a safe spot as they should in an earthquake.
Even for those unaware of the drill beforehand, organizers hope seeing others participate can help spread the word.
"We encourage people to register so that the U.S. Geological Survey can know how big of an earthquake drill it was," Pastor-Cohen said.
To register, visit www.shakeout.org