At least 41 people have died, six more have been reported missing and nearly 2,000 have been injured since Thursday as a result of the strongest tremors. The quakes have collapsed buildings and bridges, triggered fires and landslides, and even derailed a bullet train. Some small communities remain cut off, and officials say they therefore don't yet know the full scope of the tragedy.

More than 250,000 people have been either ordered to leave their homes or have left voluntarily because of damage or fears of further destructive tremors, according to officials in Kumamoto prefecture.

Quake Rescue Operations Continue Amid Japan Aftershocks

Tens of thousands of personnel are involved in the rescue-and-recovery effort, which is being hampered by heavy winds and rain.

"The Self Defense Force, police and firefighters have been working to rescue people, but there are still missing people. The government will further deploy all possible means by expanding the troop size to 25,000," Prime Minister Shinzo Abe told reporters.

His government's emergency task force held a second meeting at the prime minister's office Sunday morning to discuss response measures amid increasing reports of shortages of essential supplies in the worst-hit communities.

The central government is making available 900,000 meals, a ton of baby formula and 60,000 diapers, according to Taro Kono, the Cabinet minister in charge of disaster response.

The Japan Meteorological Agency placed the magnitude of Saturday's largest quake at 7.3, which followed Thursday's 6.5 tremor. Both were at shallow depths, onshore and located under populated areas.

Asked by VOA whether he concurred with JMA's assessment that Thursday's shallow temblor was a foreshock to the stronger quake on Saturday, University of Tokyo professor of geophysics Robert Geller said, "Now I would. But if there is a M7.6, say, tomorrow, we'd have to revise that again. Highly unlikely, yes; completely impossible, no."

Geller added that the series of powerful quakes in Kumamoto prefecture was not uncommon. "For example, there was a magnitude 7.3 quake two days before the magnitude 9.0 Tohoku quake in 2011," he said.

An active volcano in the area, Mount Aso, also erupted for the first time in a month, although Japanese authorities said the small eruption was not linked to the quake.

Abe had planned to visit Kumamoto, 1,200 kilometers southwest of the capital, to survey the damage, but decided to avoid the area while aftershocks continue. More than 400 detectable tremors, located in or near the Beppu-Shimabara rift zone, have been reported since Thursday's earthquake.

The historic Aso Shrine, more than 1,700 years old, suffered a great deal of damage. Part of a wall at the 400-year-old Kumamoto castle also collapsed.

More than 100,000 homes in Kumamoto prefecture remained without electricity Sunday, and water service has been disrupted to 422,000 households, according to the Japanese government, forcing residents to haul water from local offices to their homes.

There were no reported abnormalities at three nearby nuclear facilities, according to a government spokesman.

Operations at key manufacturing plants in the area, includin