Japan is still reeling a week after a 9.0-magnitude earthquake triggered a tsunami that devastated swathes of the country's north-east coast.
Attention has focused on the battle to avert a nuclear crisis at the stricken Fukushima Daiichi plant, but Japan is also facing a massive humanitarian challenge.
The number of people confirmed dead in the disaster now stands at more than 6,900, with another 10,000 still missing.
In some areas, residents had little time to move to higher ground before the waves came in. Seven days on, some communities remain isolated - the fate of inhabitants unknown.
Transport supply lines, particularly coastal routes, were made impassable by the wood, tangled metal and other debris left by the retreating tsunami waters.
In Miyagi prefecture - one of the worst-hit areas - more than 175 roads were damaged and two bridges destroyed, impeding access to outlying areas.
Slowly, damaged roads, ports and airports across the length of the 400km-long disaster zone are being repaired and reopened to emergency workers.
But efforts are being hampered by freezing temperatures and snow, shortages of fuel and hundreds of aftershocks - delaying deliveries of vital food and water to survivors and evacuees.
Across the region, around 90,000 rescue workers, including Japanese police and the Self-Defence Forces (SDF), are involved in relief efforts.
The government has earmarked 5.4bn yen ($67m, £41m) to pay for fuel for the SDF to transport aid and petrol to affected areas to power heaters and heavy machinery.
The Tohoku Expressway is now open to emergency vehicles and the submerged Sendai airport has cleared part of the runway for use by aircraft on relief missions.
A bus service between Sendai and Morioka is now running, connecting six prefectural capitals.
Some convenience stores are also reported to have reopened in Sendai to provide food to residents.
But there is an acute shortage of fuel because of damage to several refineries, making it harder to deliver necessities to the 500,000 made homeless by the disaster.
More than 100,000 buildings have been damaged or destroyed and an estimated 380,000 people are now being housed in 2,200 emergency shelters.
In Fukushima prefecture alone there are 103 such shelters - many have reached capacity and there are reports of overcrowding at some.
The government says it is considering transferring survivors in shelters to areas unscathed by the devastation until the construction of temporary housing is complete.
Medical teams, meanwhile, have fanned out across the north-east. As of Friday, more than 2,350 people were known to have been injured in the disaster.
The Red Cross has set up a network of emergency response units from out of which five-person teams comprising doctors and nurses operate, moving on to different evacuation centres each day.
Doctors Without Borders said its teams at evacuation centres were encountering chronic diseases among elderly people such as hypertension, cardiac diseases and diabetes.
Cases of hypothermia and dehydration are also being reported and there was an acute shortage of blankets, it said.
With temperatures dropping to as low as -5C, and no electricity or mobile phone coverage, survivors were isolated and having to cope with extreme living conditions, said Patrick Fuller of the Red Cross.
"With fuel shortages and little food coming in to the few shops that remain open, some have resorted to scavenging through the debris for packets of dried food," he said after visiting Otsuchi in Iwate prefecture.
Save the Children said that as its teams moved up the coast they were "finding pockets of profound humanitarian need".
Patrick Fuller also warned of longer-term issues that survivors would face. He described seeing an elderly couple huddled at a wood stove in the vast hall of an evacuation centre staring blankly into the flames.
"I later learn that they lost their entire family and their home," he said.
"Everyone here has lost a friend or family member to the tsunami. Coping with trauma will fast become the biggest challenge."