In this photo, Margaret Vinci, manager at the Seismological Laboratory at the California Institute of Technology (Caltech), gestures toward a row of ShakeAlert user display screens monitoring California quake activity in Pasadena, California, on June 1, 2017. Getty Images / Frederic J. Brown

A 4.5-magnitude earthquake hit California early Thursday with tremors felt in the San Francisco Bay Area. The quake struck just 1.8 miles from Berkeley, and some 40 miles northwest of San Jose.

The earthquake was centered along the Oakland-Berkeley border with its epicenter in the area of the Hayward fault, which is one of the area's most feared in the Bay Area, which could produce a magnitude 7 or greater earthquake. It is also directly underneath heavily populated areas.

There were no reports of damages, but experts said the minor quake could affect old structures in the area. U.S. Geological Survey seismologist Robert Sanders said "there’s always a possibility of some minor damage to older structures in the area."

The "strong" tremor woke thousands of people up who later reacted to the quake on social media. The quake was felt in San Francisco, Oakland, Walnut Creek and as far away as Dublin, Livermore, Union City and Milpitas. Several jolts were also felt at San Francisco International Airport.

"Nothing brings the Bay Area together more than tweeting about an #earthquake in the middle of the night," one user wrote. While another said: "I love how everyone’s first reaction in an #earthquake in SF is to tweet and not, you know, not tweet and try to survive."