Stronger Quakes, Big Aftershocks Likely

Even as Japan struggled to cope with an earthquake that shattered the western port city of Kobe, quake watchers warned that more powerful jolts could be on the way.

“The movement of active faults like this one would trigger other movements,” said Kazuo Oike, a Kyoto University seismologist. “We might face similar major quakes.”

In the weeks before Tuesday’s earthquake, Japan had an unusual amount of seismic activity. Most of the quakes were in the northern part of the country.

Tuesday’s temblor, centered under an island in Japan’s Inland Sea, killed more than 2,000 people and left close to 12,000 injured.

More than 600 aftershocks rattled the region around Kobe, 280 miles west of Tokyo. Seismologists predicted some aftershocks were likely to approach the strength of Tuesday’s quake, with a preliminary magnitude of 7.2

Katsuyuki Abe of Tokyo University’s Seismology Institute said there was a good chance that aftershocks with a magnitude of greater than 6 would strike in the coming weeks.

“People should remain cautious,” he said.

While the areas around Tokyo and the northern island of Hokkaido have suffered a series of quakes in the past few years, the western region around the commercial hubs of Osaka and Kobe has been nearly quake-free for some 40 years.

That may be about to change.

Oike of Kyoto University said this quake marks the start of a seismically active phase that could last two or three decades. In the short term, Oike said big aftershocks are likely to shake the region around Kobe for the next several months.

“Stress has been building up for some 40 years, and there is still a lot left,” he said.

As bad as the destruction was in Kobe, observers were quick to point out how much worse a similar magnitude quake in the capital would be.

Kobe has a population of 1.4 million; 12 million live in Tokyo.

“It’s unimaginable,” said Toshiyuki Katada, Musashi Tech University geology professor.

“What we observed today is a miniature version of what might happen in a possible giant quake in Tokyo.”