A powerful 7.0-magnitude earthquake struck Northern California Thursday morning, causing shaking as far south as the Bay Area, prompting a brief tsunami warning for coastal regions and setting off a swarm of smaller aftershocks that continued Friday.

The quake, dubbed the 2024 Offshore Cape Mendocino earthquake, hit at 10:44 a.m. and was centered about 10 miles southwest of Scotia in Humboldt County.

Map: Where are California’s tsunami hazard zones? Look up your address on this map Explainer: What triggered California’s 7.0 earthquake — and why aftershocks could hit San Andreas Fault Earthquake Tracker: Real-time map of California quakes It followed two smaller tremors the day before, at magnitudes 4.2 and 4.4.

A tsunami warning was issued across Northern California, urging coastal residents to evacuate immediately to higher ground. However, within an hour, federal officials downgraded the warning, stating that no significant tsunami waves were expected. Although the tsunami did not materialize, authorities at all levels stressed that there was significant initial concern, and it was not a false alarm.

Swarm of aftershocks A swarm of small aftershocks pulsed through Northern California Friday morning in the wake of a major, 7.0-magnitude earthquake on Thursday, according to data from the U.S. Geological Survey.

Nearly 30 aftershocks were recorded on the USGS’s earthquake tracker within an hour’s drive of Petrolia, a small unincorporated community in Humboldt County.

California tsunami hazards map California’s tsunami warning on Thursday after the 7.0-magnitude earthquake off the Humboldt County coast was quickly canceled. But it was a reminder of the hazards facing residents and visitors along state beaches, harbors and certain low-lying neighborhoods near the shore – and the need to know where to go in the case of a tsunami.

The California Geological Survey has created maps showing tsunami hazard zones along the entire coast that are a helpful start. However, they were developed with an extreme event in mind, coming from a different location than Thursday’s quake. To help people know where to escape, the map projects where water might inundate the shoreline during a tsunami caused by a rare, but possible, gigantic earthquake in Alaska.

See the map here.

At least eight aftershocks have measured 4.0 or more Dozens of aftershocks have hit Northern California following the magnitude 7.0 quake that struck off the Cape Mendocino coast on Thursday morning. At least eight of the aftershocks have measured at 4.0 or above on the Richter scale, with the biggest of those hitting 4.7 two minutes after the initial quake. the U.S. Geological Survey says aftershocks can continue for weeks.