Powerful aftershocks from the Mount Nyiragongo volcano rocked the eastern DR Congo city of Goma on Tuesday as the death toll from the disaster climbed to 32 and thousands were feared homeless.
Three days after Africa's most active volcano roared back into life, spewing lava that reached the outskirts of the city of 1.5 million people, tremors were shaking the region every 10 to 15 minutes.
And two major cracks, running up to several hundred metres (yards) in length and dozens of centimetres (roughly two feet) in width in some places, opened up near the city's main hospital and on a major highway near the airport, worrying residents who have only just returned home after Saturday's eruption.
"We don't know what to do -- we're in a quandary, there's no instructions from the authorities, even though everything is moving," said Goma resident Furaha Nyirere, visibly anxious.
"We're terrified," said Ishara Bashinenga, also of Goma. "If only they could tell us where to go, because we fear the worst."
But a government official who requested anonymity said "the option of a full evacuation... has not been decided yet," adding that assisting the victims was the main priority for now.
The Goma airport is closed, as well as that of nearby Bukavu, which opened briefly on Monday before being ordered closed again on Tuesday.
At least four buildings in Goma partially collapsed, including a three-storey building in which eight people were seriously injured, police said.
A massive expanse of rocky, black lava blocked the road to Butembo, vital for getting supplies to Goma, over nearly a kilometre (half a mile).
"We are all living in fear of a fresh eruption," a local official from an international organisation told AFP.
"The aftershocks are very intense. A lot of people slept outside... scared that their homes were going to collapse," the official said.
Across the nearby border, the Rwanda Seismic Monitor said it had detected dozens of aftershocks including a 5.3 magnitude earthquake in the region at 0903 GMT, as well as a 4.6 magnitude tremor an hour earlier.
An official of the Goma Vulcanology Institute, Celestin Kasereka Mahinda, said more damage could be expected even while the tremors are abating.
"The Earth ejected lava onto the surface (so) a void was created in the interior," he said. "This void needs to be filled little by little to restore balance."
He warned that the ash emanating from the volcano is "very toxic" and people must not use rainwater for "whatever reason, such as washing vegetables".
Goma, a city on the shores of Lake Kivu, lies just 12 kilometres (about seven miles) from Mount Nyiragongo.
Tens of thousands of residents fled in panic, many of them to Rwanda, when it began erupting on Saturday evening.
Two rivers of molten rock flowed from the volcano at a height of 1,800 metres (5,900 feet).
One headed towards Goma, stopping at the very outskirts of the city.
- Fears of fresh eruption -
It engulfed homes in its wake, smothering the surrounding area with suffocating gas.
"Thirty-two people died in incidents linked to the eruption, including seven people killed by lava and five asphyxiated by gases," the UN refugee agency UNHCR said in Geneva.
The previous death toll, drawn from NGOs and other sources, was 20.
Five people died from suffocation on Monday after they tried to cross the cooling lava some 13 kilometres north of Goma, civil society leader Mambo Kawaya told AFP.
The UN Children's Fund (UNICEF) said at least 150 children were separated rom their parents and another 170 are missing.
A so-called strato-volcano nearly 3,500 metres (11,500 feet) high, Nyiragongo straddles the East African Rift tectonic divide.
Its last major eruption, in 2002, claimed around 100 lives.
- Water access fears -
In an interview with AFP, Raphael Tenaud, deputy head of the International Committee of the Red Cross (ICRC) delegation in Goma, said lava had destroyed four large villages and damaged 12 others.
Humanitarian groups estimate that between 900 and 2,500 dwellings were destroyed representing around 5,000 newly homeless people, he said.
Some 25,000 people fled on Saturday and Sunday, Tenaud said.
"Many of these displaced people have started to return to Goma, some have even come back to the site of the disaster, near the lava flow," he said.
"Some are still displaced as they are afraid to come back," he added.
Damage to a reservoir has potentially affected water supplies for around half a million people, Tenaud said.
"The main problem will be... access to potable water and all the consequences that may stem from that," he said.
The ICRC will revive a disused pumping station to draw water, and water will also be distributed by tanker truck, Tenaud added.