Cities and counties along the Pacific U.S. coast braced for a tsunami that is expected to reached Northern California at 11:20 a.m. New York time, the result of an 8.9 magnitude earthquake in Japan.

Law enforcement in Santa Cruz, a coastal city 60 miles south of San Francisco, recommended that residents in some areas evacuate to higher ground, while San Francisco police shut a 4- mile stretch of highway that runs along the city’s western edge.

Waves are expected to be two- to three feet high in and near San Francisco, and may reach as high as five feet high near Santa Cruz, according to the National Oceanic and Atmospheric Administration. The tsunami’s effect will be blunted in the U.S. at it hits at the lowest tide point of the day, NOAA said.

"We want to ensure that in the unlikely event something more significant does materialize that we’re prepared," said Steve Clark, deputy chief of police of the Santa Cruz Police Department.

The West Coast and Alaska Tsunami Warning Center raised an alert for the west coast of the U.S. after the strongest earthquake on record for Japan unleashed waves that killed hundreds of people and submerged towns on the Asian nation’s northern coast.

Santa Cruz’s emergency operations center notified 6,600 residents who live near the coast to evacuate their homes, said Enrique Sahagun, public information officer of Santa Cruz County, which has 250,000 residents, Sahagun estimates.

Hawaii was hit by a 1-meter (39-inch) wave, according to scientists at the Pacific Tsunami Warning Center, which was anticipating scattered damage, not major destruction.

Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea. They typically hit the shore as a series of waves over a period of 10 to 12 hours.