The volcanoes around Goma often spew smoke and steam
Scientists in the Democratic Republic of Congo have recorded significant increased volcanic activity around Goma in the east of the country.
Half of the city was destroyed in 2002 after the nearest of two volcanoes, Mount Nyiragongo, erupted.
Now Mount Nyamulagira, which lies 25km (16 miles) from Goma, may soon erupt.
Scientist Dieudonne Wafula told the BBC if it did erupt, there would not be an immediate threat to Goma, but some key rural roads could be cut off.
Rise in temperature
The BBC's Mark Doyle says the volcanoes loom over Goma, spewing smoke and steam even when they are not considered to be an immediate threat.
By day, the air in the city, the de facto capital of eastern DR Congo, is thick with volcanic dust, he says.
By night, residents can often see the red glow of burning lava trickling out of the summit of the nearest volcano, Mount Nyiragongo.
Mr Wafula, who heads Goma's Volcano Observatory, said significantly increased temperatures had been recorded around Mount Nyiragongo recently and a larger than usual cloud of volcanic dust was being thrown into the skies.
However, he said, it was Mount Nyamulagira that was likely to erupt.
The representative of the United Nations refugee agency in Goma, which closely monitors population movements, said he was not aware of any panic in the region.
A resident of Goma told the BBC said people were talking about the volcanoes and that they had noticed a rise in temperature in recent days, but that otherwise the situation inside Goma was normal.