A day after a 6.0 magnitude earthquake jostled a wide swath of Northern California, residents in Southern California got a jolt Friday morning.
But what some thought was another quake turned out to be a sonic boom that was recorded about 9:20 a.m., according to the U.S. Geological Survey.
The blast of sound energy occurred about one mile south of San Dimas, the USGS reported. But the effects rippled out toward the coast, where several people reported feeling an earthquake-like rumble.
A sonic boom is a thunder-like noise that can be heard when an aircraft flies faster than the speed of sound, according to NASA.
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