Early morning 3.4-magnitude quake wakes up Southern California, geologists say

A 3.4-magnitude earthquake shook Southern California near Ontario and Rancho Cucamonga at 3:33 a.m. Pacific time Tuesday, March 22, the U.S. Geological Survey reports.

The 4.5-mile deep quake hit 4 miles east of Ontario, according to the USGS. Hundreds of people from as far away as Simi Valley and San Diego reported feeling the tremor to the agency.

“You could hear it before the jolt. Woke us up,” one person wrote on Twitter.

“It really freaked me out it sounded like someone was opening a sliding glass door I heard it before it even happened I was like ‘what is that sound?’ Then it hit! Freaked me out!!!” another Twitter post read.

Some were surprised to discover California has a city named Ontario.

“The real earthquake may be, Ontario shifted from Canada to California?!” read one Twitter post.

“Every time ppl freak out over earthquakes in cali i’m literally always like the mickey mouse ‘wha happah’ video until i realize it was just a stupid earthquake that i didn’t even feel,” one person wrote on Twitter. “Also since when does cali have an ‘Ontario?’”

Ontario is a city of 176,000 people in San Bernardino County east of Los Angeles.

Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says. It replaces the old Richter scale.

Quakes between 2.5 and 5.4 magnitude are often felt but rarely cause much damage, according to Michigan Tech. Quakes below 2.5 magnitude are seldom felt by most people.