Three farming villagers and as many as 100 farmers in a remote region of Zaire were incinerated early this year when a molten lake of lava rushed down the sides of a volcano that had not erupted since 1928.

Without any warning or any gas-like explosion, according to a Smithsonian Institution geologist, the sides of the Nyiragongo volcano in eastern Zaire broke open on the morning of Jan. 10 and spilled down the 10,000-foot mountain the lava that had been simmering in the volcano's crater for 49 years.

The lava moved down the moutain at speeds of almost 40 miles an hour, covering the south side of the mountain and the countryside out six miles from the base of the mountain in less than an hour. Farmers tilling fields on the slopes of the mountain were incinerated immediately by the lava, whose temperature was estimated at 1,800 degrees F.

"Lava usually flows slowly enough that people in its path can get out of the way," said geologist Lindsay McClelland of the Smithsonian's Scientific Event Alert Network, "but the lava from this eruption traveled so fast that many people were unable to escape."

McClelland has been receiving reports of the disaster for months from European scientists who have visited the volcano. He said he has also heard from scientists working for the Institute of Scientific Research for Central Africa. The eruption took place in the Kivu Province of eastern Zaire near its border with Rwanda.

According to the scientists' reports, at least five fissures opened simultaneously on the north and south flanks of the volcano, draining the lake of molten lava.

A thin crust had covered the lava lake all those years, insulating it against the cool air at the top ofthe mountain. Heat moving from the volcanic interior of the mountain kept the lava molten.

McClelland said the farmers and three villages that were incinerated were all on the south slope of the mountain. Had the lava not spilled down the north slope as well, it would have burned parts or all of the city of Goma on the south end of the slope. The lava flow stopped three miles from Goma, a city of 65,000 population.