Filed 6:45 am: The earthquake that struck the northeast coast of Japan last night has sent tsunami waves surging across the Pacific ocean, leading to tsunami warnings along the US west coast -- including the San Francisco Bay Area. Evacuation orders have been issued for some beach areas (including in San Mateo County), but not in Oakland.

How might this tsunami affect Oakland? Probably not much. Here's what we know so far...

I was awakened at 4:15 by a text message from my sister in Florida: "I heard there's a wall of water heading your way from the earthquake in Japan." But in fact, effects around Oakland appear likely to be relatively mild.

Tidal surges of about two feet are expected to arrive in San Francisco at 8:08 am, according to the West Coast and Alaska Tsunami Warning Center (WCATWC).

But specifically for Alameda, a surge amplitude of 0.29 meters (just under one foot) is expected. There would probably be several surges spread over a few hours -- so people who are right along the waterline should take precautions.

According to Weather Underground, "A one-foot deep storm surge can sweep your car off the road, and it is difficult to stand in a six-inch surge." So caution in areas near the bayfront is warranted. Still, it doesn't look like much of Oakland is in for much of a hit from this particular event.

WCATWC issued this tsunami warning, which includes "coastal areas of California and Oregon from Point Concepcion, California to the Oregon-Washington border." The agency recommends: "All coastal residents in the warning area who are near the beach or in low-lying regions should move immediately inland to higher ground and away from all harbors and inlets including those sheltered directly from the sea. ...All residents within the warned area should be alert for instructions broadcast from their local civil authorities." [Emphasis added]

Much of Oakland's flatlands are indeed "low lying," but since we're inland from the Pacific coast, we're more sheltered than direct coastal areas from ocean-crossing tsunamis. The Oakland International Airport is vulnerable to tidal surges, but as of this time the airport is reporting no flight schedule disruptions.

The California Dept. of Conservation has prepared some Alameda County tsunami inundation maps, showing which parts of town might get inundated by a tsunami. This would be most likely to happen with a local earthquake, so it is information people in Oakland should know about.

According to these maps, the parts of Oakland most at risk from a tsunami surge are:

• Around I-880, west of Mandela Parkway -- including the Oakland Army Base, the Oakland Naval Supply Center, and the Prescott, Lower Bottoms, and South Prescott neighborhoods.
• On the waterfront, south of about 3rd. St -- including Jack London Square
• Up to Laney College, near the inlet to Lake Merritt
• Southwest of I-880, from Oakland International Airport up to the Oakland Coliseum area.