By JAY ALABASTER, Associated Press Jay Alabaster, Associated Press– Mon May 9, 5:46 am ET

    – When water begins to trickle down the streets of her coastal neighborhood, Yoshiko Takahashi knows it is time to hurry home.

Twice a day, the flow steadily increases until it is knee-deep, carrying fish and debris by her front door and trapping people in their homes. Those still on the streets slosh through the sea water in rubber boots or on bicycle.

"I look out the window, and it's like our houses are in the middle of the ocean," says Takahashi, who moved in three years ago.

The March 11 earthquake that hit eastern Japan was so powerful it pulled the entire country out and down into the sea. The mostly devastated coastal communities now face regular flooding, because of their lower elevation and damage to sea walls from the massive tsunamis triggered by the quake.

In port cities such as Onagawa and Kesennuma, the tide flows in and out among crumpled homes and warehouses along now uninhabited streets.

A cluster of neighborhoods in Ishinomaki city is rare in that it escaped tsunami damage through fortuitous geography. So, many residents still live in their homes, and they now face a daily trial: The area floods at high tide, and the normally sleepy streets turn frantic as residents rush home before the water rises too high.

"I just try to get all my shopping and chores done by 3 p.m.," says Takuya Kondo, 32, who lives with his family in his childhood home.

Most houses sit above the water's reach, but travel by car becomes impossible and the sewage system swamps, rendering toilets unusable.

Scientists say the new conditions are permanent.

Japan's northern half sits on the North American tectonic plate. The Pacific plate, which is mostly undersea, normally slides under this plate, slowly nudging the country west. But in the earthquake, the fault line between the two plates ruptured, and the North American plate slid up and out along the Pacific plate.

The rising edge of plate caused the sea floor off Japan's eastern coast to bulge up — one measuring station run by Tohoku University reported an underwater rise of 16 feet (5 meters) — creating the tsunami that devastated the coast. The portion of the plate under Japan was pulled lower as it slid toward the ocean, which caused a corresponding plunge in elevation under the country.

Some areas in Ishinomaki moved southeast 17 feet (5.3 meters) and sank 4 feet (1.2 meters) lower.

"We thought this slippage would happen gradually, bit by bit. We didn't expect it to happen all at once," says Testuro Imakiire, a researcher at Japan's Geospatial Information Authority, the government body in charge of mapping and surveys.

Imakiire says the quake was powerful enough to move the entire country, the first time this has been recorded since measurements began in the late 19th century. In Tokyo, 210 miles (340 kilometers) from Ishinomaki, parts of the city moved 9 inches (24 centimeters) seaward.

The drop lower was most pronounced around Ishinomaki, the area closest to the epicenter. The effects are apparent: Manholes, supported by underground piping, jut out of streets that fell around them. Telephone poles sank even farther, leaving wires at head height.

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