All of California’s vulnerabilities seemed to be on display on Sunday afternoon. In addition to the lashing rains of a very rare tropical storm, firefighters near the Oregon border were battling a wildfire that grew by 2,000 acres overnight.

And then the ground shook.

The 5.1-magnitude earthquake centered near Ojai, Calif., was unlikely to have caused serious damage. But residents in Los Angeles, 60 miles southeast of the epicenter, felt swaying that lasted long enough to take notice.

A 3.5-magnitude earthquake often feels like a quick jolt, as if someone just bumped into your desk. The Ojai earthquake was slightly more significant than that and may have caused some minor cracking in walls, according to Jana Pursley, a geophysicist with the U.S. Geological Survey.

Though the earthquake was felt in much of Santa Barbara County, just 15 miles from Ojai, there haven’t been reports of damage so far, said Jackie Ruiz, public information officer for the Santa Barbara County Office of Emergency Management.

“Generally it’s sounding as if people felt the shake, and they got the alerts, and no impacts,” Ms. Ruiz said.

She said that local officials on Sunday were juggling multiple emergencies, with rainfall from the tropical storm expected to peak between 4 p.m. and 10 p.m., and a fire that began on Saturday in the northern part of the county continuing to burn.

“Absolutely a busy day,” Ms. Ruiz said.

But Sunday’s earthquake was moderate compared to some of the larger ones that have caused extensive destruction in California. The 6.7-magnitude earthquake that struck the Northridge neighborhood of Los Angeles in 1994 released 125 times more energy than today’s Ojai earthquake.

The Loma Prieta earthquake, which left more than 60 people dead in the San Francisco Bay Area in 1989, was 253 times more powerful than the Ojai quake.