More than 10,000 people huddled in evacuation centers in northwest Japan on Tuesday after a strong earthquake the previous day killed nine people and injured more than 1,000.
Following are some facts about Japan and earthquakes.
* Japan, situated on the Ring of Fire arc of volcanoes and ocean trenches that partly encircles the Pacific Basin, accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.
* A tremor occurs in Japan at least every five minutes, and each year there are up to 2,000 quakes that can be felt by people.
* The Great Kanto earthquake of September 1, 1923, which had a magnitude of 7.9, killed more than 140,000 people in the Tokyo area. Seismologists have said another such quake could strike the city at any time.
* On January 16, 1995, an earthquake with a magnitude of 7.3 hit central Japan, devastating the western port city of Kobe. It was the worst earthquake to hit Japan in 50 years, killing more than 6,400 and causing an estimated $100 billion in damage.
* On October 23, 2004, a 6.8 magnitude quake struck the Niigata region, about 250 km (150 miles) north of Tokyo, killing 65 people and injuring 3,000.
* On March 25, 2007, a 6.9 magnitude quake struck the Noto peninsula in Ishikawa prefecture, about 300 km west of Tokyo, killing one person, injuring more than 200 and destroying hundreds of homes.
* The Tokyo metropolitan government said in March 2006 that a magnitude 7.3 earthquake under Tokyo would probably kill more than 5,600 people and injure almost 160,000. Official estimates of economic damage have topped more than $1 trillion.
* German insurer Munich Re was even more pessimistic, saying in 2004 that a severe earthquake in the Tokyo-Yokohama area would kill hundreds of thousands of people, cause damage running into trillions of dollars and have global economic repercussions.
* The Tokyo-Yokohama metropolis, with a population of 35 million, has the highest at risk rating from natural disasters such as earthquakes of any of the world's 30 megacities, the report said.