A 5.6-magnitude earthquake hit near Mendocino County early last week.
The seismic event sent tremors through Northern California across the area.
Cell phones across the Bay Area flashed with ShakeAlert warnings.
The shaking reached San Francisco and adjacent locales.
Reports say little damage showed up immediately after.
Officials keep checking extra shakes.
They urge people to stay ready as a precaution.
5.6 earthquake reported in Northern California, triggers alert across Bay Area San Francisco Chronicle
Shake alert lights up Bay Area phones Wednesday morning after 5.6 quake hits Mendocino KRON4
Magnitude 5.6 earthquake felt across Northern California, USGS says KCRA
Northern California hit by magnitude 5.6 earthquake in Mendocino County CBS News
Magnitude-5.6 earthquake shakes parts of Northern California NBC Los Angeles