Volcano Watch — Local volcanologist to assess Zaire eruption

The U.S. Geological Survey has a Volcano Disaster Assistance Program (VDAP) that provides scientific and technical assistance during international volcanic crises.

The scientists and technicians who respond to these crises are drawn mainly from the Cascades, the Hawaiian, and the Alaska Volcano Observatories and from regional centers in California, Colorado, and Virginia. A cache of monitoring equipment is maintained at the Cascades Volcano Observatory so that responses can be executed quickly. VDAP is jointly supported by U.S. AlD's Office of Foreign Disaster Assistance and U.S. Geological Survey's Volcano Hazards Program.

In the past, VDAP has provided assistance during eruptions in Cameroon, Chile, Columbia, Ecuador, Guatemala, Indonesia, Mexico, the Northern Marianas Islands, Peru, and the Phillipines. A new potential volcanic crisis has recently activated the response team, and two scientists will soon be on their way to Zaire in Central Africa.

Two different volcanoes in east Zaire began erupting within the past six weeks. The first is Nyiragongo, a steep-sided stratovolcano surmounted by a deep summit crater. It last erupted 11 years ago, but on June 23, new eruptions began, and a lava lake formed in the summit crater. The summit is only 18 kilometers (11 miles) north of the city of Goma, and a red glow was reported seen above the volcano. Goma is now the temporary home to an estimated million refugees as a result of the Rwandan civil war. An active lava lake resided in the 1.2-kilometer-deep crater from 1927-1977. In 1977 the lake drained and lava erupted from fissures on the north, south and west flanks of the volcano.

The lava from Nyiragongo has an unusual composition, characterized by low silica, that causes it to be very fluid and to flow rapidly. The 1977 flows moved downslope at speeds up to 60 kilometers/hour, killed 70 people, and advanced to within about 600 meters of the Goma airport. In 1982 lava fountaining and phreatic(steam) explosions occurred in the crater and formed a small lava lake.

The second volcano, Nyamuragira, is located only 13 kilometers north-northwest of Nyiragongo. It began erupting on July 4 from a fissure, or fissures, on the west or southwest flank of the volcano. Reports indicate that the eruption is producing tephra and volcanic dust or ash that is being carried by the wind and causing crop damage up to 35 kilometers away. Press reports in late July indicated that volcanic ash fell on the refugee camps. Nyamuragira is a large shield volcano, similar in form to that of Hawaiian volcanoes, with a 2-kilometer-wide summit crater. Numerous historical eruptions have occurred within the summit crater and from radial fissures on the fla~ks of the volcano. Flank eruptions in 1980, 1981, 1984, 1986, 1989, and l991-1993 produced flows up to 30 kilometers long. A number of twentieth century flows reached the shores of Lake Kivu northwest of Goma. The Global Volcanism Network of the Smithsonian Institution compiled much of the above information on the current and past activity at Nyiragonga and Nyamuragira.

Next week, two volcanologists, Dr. Jack Lockwood from the Hawaiian Volcano Observatory and Dr. Tom Casadevall from the Denver Regional Center, will depart for Zaire to evaluate the lava flow hazards posed by the two volcanoes to the refugee camps and the possible effects of volcanic ash on aircraft involved in the relief effort. Dr. Lockwood, who responded to the Lake Nyos disaster in 1986, is an expert on lava flow hazards. Dr. Casadevall is an expert on volcanic ash and aircraft safety. Doctors Lockwood and Casadevall will spend a week to 10 days assessing the situation in Zaire and will make recommendations to the U.S. State Department regarding appropriate response.