An earthquake measured at magnitude 4.0 and centered near Parkfield jolted some North County residents awake this morning.
According to the U.S. Geological Survey, the temblor struck at 4:30 a.m. and was 3 miles from Parkfield, 14 miles from Shandon and 18 miles from San Miguel.
One man working in downtown Paso Robles at the time of the quake said windows shook and he heard a loud popping noise.
No aftershocks have been reported, according to USGS.
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Parkfield is known as the origination point for regular quakes and has been the site of a major earthquake study for nearly 30 years.