By CBSLA Staff

LOS ANGELES (CBSLA) — A shudder felt across most of Southern California wasn’t an earthquake – it was a sonic boom, according to the U.S. Geological Survey.

The sonic boom was felt at about 9:20 a.m. Friday across a wide swath of Southern California. And even though it wasn’t an earthquake, the USGS created an event page for it that indicated it was felt from Huntington Beach to Thousand Oaks along the coast, and as far inland as Lake Elsinore.

Earthquake expert Dr. Lucy Jones said that seismograms clearly showed the earth did not move – just the air, which suggests the source was a supersonic aircraft over the ocean.

It’s unclear what aircraft may have caused the sonic boom.