The number of earth tremors on and around the 2,361-meter (7,746-feet) mountain has increased "exponentially" over the past three months, indicating an imminent eruption, said Mallory Leclerc of the Volcanological Observatory in the Comoros' capital, Moroni.

"If the current situation continues, the risk of eruption in the short term is strong," he said.

Around 100 earth tremors a day had been reported in August against around two a day in June, scientists at the observatory have said.

If the mountain erupts, it could be a dramatic andisitic eruption -- driven by steam -- because Karthala has a lake at the summit of its crater, Leclerc said.

Karthala last erupted in 1991. An eruption in 1977 buried the village of Singani, some 20 kilometers (12 miles) south of Moroni, in lava, but no one was killed.

TERRA.WIRE