SAN DIEGO — An earthquake with a preliminary magnitude of 4.1 struck near Palomar Observatory in north San Diego County Sunday morning, according to United States Geological Survey.

The quake was reported at 9:46 a.m. about three miles to the west-southwest of the observatory, USGS reported. The astronomical research center is located atop Palomar Mountain, about 26 miles northeast of Valley Center.

The quake was felt as far south as Chula Vista and as far north as Riverside County, USGS reported.

Seismic readings for earthquakes are sometimes adjusted over time as analysts get more data. In the case of Sunday’s quake, the preliminary magnitude was briefly modified to 4.0, before being bumped back up to 4.1.

An earthquake with a preliminary magnitude of 4.0 struck near the Palomar Observatory in north San Diego County Sunday morning, according to United States Geological Survey. (USGS)

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