The lava was still moving. But it had cooled enough for a matt grey skin to have formed on its surface.
The lava was still moving. But it had cooled enough for a matt grey skin to have formed on its surface. Gingerly, the people who had fled their homes four days ago when the red-hot molten rock first poured from Mount Nyiragongo picked their way across the brittle crust.
When it became too hot for the soles of their feet, they ran. But they tried to avoid stumbling. Like ice, at the other end of the temperature spectrum, a crust forms on top. If that is cracked by a careless foot, human flesh is plunged into lava as hot as 1,000C.
Yet still the flow of people continued, a human river defying the one of molten rock which they traversed.
This was Goma, the lakeside African town in eastern Congo, at the foot of Mount Nyiragongo, the volcano which erupted on Thursday sending millions of tons of neon-bright orange lava spilling down its slopes. Most of the 500,000 residents fled, many of them into neighbouring Rwanda.
But yesterday they began returning home. Shunning an international aid effort, they walked away from the two sites where aid-workers had ordered sheaves of plastic sheeting for improvised tents. Instead, they retraced their steps, carrying on their heads their household possessions.
Women balanced huge bundles of sticks and clothes. Men bore battered and bursting suitcases. Children carried chickens. One old chap even balanced a bicycle, precariously, on his shoulders.
"Now you must run," John Nfune, told his fellow returnees as they reached a 100-metre-wide lava flow. There was no way around. And the hot, dense, black mud was radiating intense waves of heat.
The young men dashed across. But the old women shuffled forward, preferring the blast of heat to the risks of tripping and falling on even hotter molten stone nearby, or of cracking the cooling surface.
Coming in the opposite direction was a counter-flow of people with similarly preposterous burdens who had found their homes submerged beneath the volcanic mud and ash, and who were bringing what little survived to start again somewhere else. But not in Rwanda, where the main aid effort is focused. Most said they would prefer to go to other Congolese cities, such as Bukavu, Kalemie or Kisangani.
Yet the vast majority on the move were journeying towards the volcano, which experts say could erupt again. "People are pouring back into Goma," said Alison Preston, an aid-worker with the World Vision charity. "From what I can see it is a massive level of returns."
It was a decision fraught with danger. The residual heat was not the only peril. Doctors were warning that the fumes from the lava – which is giving off a pungent stench of sulphur and a smell like burning rubber. "The fumes are very toxic," said Dr Achille Mudiandanbu at a hospital run by the Sisters of Charity. "They can kill you."
Then there was the risk from contaminated water. The volcano has destroyed both water treatment plants in the town. People are resorting to drinking from Lake Kivu, which is already polluted. A cholera epidemic followed the last eruption of Mount Nyiragongo in 1977.
And experts fear that igneous extrusions into the lake may stir up natural gases in the lake which could cause explosions.
The first aerial pictures since the eruption revealed the scale of the devastation. Almost half of the city is submerged in a sea of lava which is up to 3-meters deep in places.
Despite all this, the bitter experience of local people is that refugee camps are a worse option. They are a deadly reminder of the genocide, banditry and gangsterism during and after the Rwandan civil war less than a decade ago.
Former residents of the camps were unequivocal about their desire to leave. "There is no food, no water, no sanitation. We are here like animals," said Richard Mwambo, a teacher who was returning from a Rwandan camp. "If we are to die, it is better to die in Congo, not Rwanda."
Kasonyo Tipe, a Goma merchant, said he could better support himself in Congo. "Our money here is useless because the exchange rate is so high," he said. "Take us back to where we can do business."
Aid workers in the region are furiously reworking their plans. Britain has pledged £2m, half of which is already on its way to the African nation, according to the Secretary of State for International Development, Clare Short. The first British aid flight, carrying water purification equipment, arrived yesterday. Other countries have responded swiftly too: Belgium, the former colonial power, has pledged $1.1m (£765,000) and the US, $224,000.
But now aid will have to be diverted from the camps to Goma itself, which will be a more difficult task. "This will complicate things considerably," said Paul Stromberg, a spokesman for the UN High Commission for Refugees, not least because of the eastern Congo's limited infrastructure, the inheritance of 30 years of dictatorship by Mobutu Sese Seko, in the far east of the country, formerly Zaire.
The Foreign Secretary, Jack Straw, with his French counterpart, Hubert Vedrine, will begin a three-day tour of the war-ravaged central Africa region tomorrow.
They will not visit Goma, though. If they did, they would find a people uncowed by the scale of what has occurred. "Our houses were built on lava flows that engulfed the town decades ago," said Dieudonne Kabongo, 37, a teacher with five children, as he watched the crowds climbing on to the start of the sulphurous lava path which would take them home. "There's still a way to repair our houses," he said. "There's no electricity, but the cables are there. We can rebuild."Reuse content