A series of quakes in northern Niigata prefecture, led by a tremor measuring 6.8 on the Richter scale on Saturday, buckled roads, smashed houses and left 25 people dead, 1,960 injured and 97,800 seeking refuge.

As images of blanket-wearing victims in shelters were broadcast around the nation, residents in Tokyo -- where the 1923 Great Kanto Earthquake left 142,807 dead or unaccounted for -- prepared themselves for tragedy.

"Every time there is an earthquake, I prepare a little more to prevent furniture from falling down by putting hooks on the walls," said Masami Murata, a 51-year-old office worker.

"My family has talked about meeting at a nearby park if a disaster occurs," he said.

The quakes came hard on the heels of the worst typhoon season on record, including Typhoon Tokage which left 80 dead as it plowed through central Japan Wednesday.

"I bought a disaster kit that contains water, food and wet tissues when my daughter was born," Tokyo housewife Akimi Morita, 34, said of her four-year-old child Yumi.

"When I was a child, people were already saying a huge earthquake would come to the Tokyo area. So I'm prepared for a natural disaster."

Experts said there was a risk living anywhere in Japan, which comes under the constant strain of the westward-moving Pacific tectonic plate.

Saturday's earthquake and some 380 aftershocks occurred in a region about 200 kilometers (125 miles) northwest of Tokyo that had not experienced a deadly tremor in 175 years.

Scholars debated whether it was the result of a "seismic gap" where pressure had been bottled up or if other reasons were to blame.

"Depending on the researcher, the attitude is different, but I was personally surprised that an earthquake occurred there," said Keiji Doi, assistant professor at the University of Tokyo's Earthquake Research Center.

"There had not been a very big earthquake in this area for around 100 years," he said, adding that usually indicates relative stability.

The last deadly quake in the area occurred December 18, 1828, about 30 kilometers north of Saturday's epicenter. It measured an estimated 6.9 on the Richter scale and killed 1,700 people and flattened 13,000 homes, Doi said.

An October 4, 1933 a quake at an estimated 6.1 on the Richter scale shook Ojiya and Kawaguchi -- municipalities badly hit over the weekend -- but no injuries were recorded, he said.

Just two weeks ago the science ministry's Earthquake Research Committee said there was a two percent or less chance of having an 8.0 quake in the next 30 years along fault lines running northward from Nagaoka, just north of the hard-hit areas.

But the committee on Sunday ruled out a link to the weekend tremors, which appeared spread along different faults.

Satellite images of geographical changes and electromagnetic wave patterns have yet to accurately predict earthquakes, said emeritus professor Ryohei Morimoto, formerly with the research center.

"From geographic changes we can tell which areas are dangerous but not when a quake will occur," he said.

Doi said the weekend quakes did nothing to reduce the risk to Tokyo, which is near the intersection of at least three known tectonic plates.

"The danger of an earthquake in the Tokyo region remains the same," Doi said.

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