"Four big obstacles"

• Lack of fuel, created by the difficulty of getting supplies to the neediest areas and aggravated by hoarding, is "throwing a spanner into everything," Markus said.

• Harsh winter weather is complicating an already difficult relief effort, making it so "you can't get to certain areas,

• Radiation fears have not only triggered a no-fly zone around Fukushima, further complicating transportation, but are also forcing rescue workers to take extra precautions that slow deliveries even more.

Other impacts More than 452,000 people are staying in temporary shelters. Transportation and communications systems were largely paralyzed in the immediate aftermath of the quake, but air and ground travel are said to be near normal. Still, many roads were severely damaged and travel within the hard-hit areas remains difficult. Large swaths of the country remain without power — estimates range from 1.2 million to 4 million households. Rolling blackouts have been imposed to conserve power around Tokyo and northern Honshu. Some commodities, including gas, medicine and other necessities, are scarce. The Japanese government estimates that 1.4 million households have no access to safe drinking water.