Volcano World

Photograph of Fogo eruption, looking east towards Mt. Pico

Credit: Frank Trusdell, U.S. Geological Survey, April 25, 1995.

For the first time since 1951, in 1995 an eruption occurred in the volcanic Cape Verde Islands. To understand the unusual circumstances of the eruption you must understand that people live on the floor of this active volcano! The island of Fogo is one massive volcanic cone, with an 8 km wide caldera that opens out to the east. Some of the best farmland on the island is on the relatively flat floor of the caldera, so people choose to live there, knowing that someday an eruption may chase them out.

Late on the evening of April 2, 1995 a red glow was seen on Fogo, and early the next morning a new fracture was spurting out columns of red lava and ash was falling. This must have been a startling sight for the people who lived nearby and most of them immediately evacuated - or left - the area of the eruption. Altogether perhaps as many as 5000 people moved out of the caldera, finding refuge in villages along the coast, away from the eruptions.

Map source: Smithsonian Institution's Bulletin of the Global Volcanism Network, v. 20, no. 3, March 1995.

Two aa lava flows were formed, with the second one flowing on top of the first one. The flows are about 4 kilometer long and about 600 m wide. The measured temperature was 1026 C. At the vent where lava came out of the ground a small cinder cone was built. By the middle of April it was 140 m high. The lava flows have destroyed a few houses and much valuable land that was used for farming and grazing of cattle.

Photograph of Fogo eruption, Frank Trusdell, U.S. Geological Survey, April 15, 1995.

Activity at Fogo continued from mid-April to early May. Intermittent fire fountains and Strombolian activity reached heights of greater than 1,000 feet (300 m) and the cone grew to a height of 520 feet (160 m). Lava flows were sluggish. On April 23, deafening explosions from the vents shook the ground with concussion waves. A new vent formed and erupted lava that flowed 2,300 feet (700 m) to the west in only a few hours. The next day, Strombolian activity decreased and only a small volume of lava was erupted from the new vent. From April 25 to 27, quiet periods were punctuated by lava fountains that rose about 150 feet (50 m) over the crater. From late April to May 2, lava continued to flow from the crater but at a much reduced rate. News reports on May 7 indicated that the eruption gained in strength slightly and increased the rate of lava production.

Photograph of fire fountain at Fogo, Frank Trusdell, U.S. Geological Survey, April 13, 1995.

As of May 18, it is estimated that 1.6 square miles (4.2 square km) of productive land have been covered. Boca de Fonte, a village with a population of 56 people, was destroyed. Flow fronts were 1,000 feet (300 m) from the village of Portela. About 1,000 people remained in shleters.

Previous Eruptions and Consequences 
The Cape Verde Islands were discovered by Portuguese sailors at about the time Columbus discovered America. From about 1500 AD until 1760 AD, Pico, the volcanic peak on the floor of the Fogo caldera was constantly erupting. Fogo was a lighthouse for sailers in this part of the Atlantic Ocean. Since 1760 six eruptions occurred, most making lava flows that destroyed farmland and houses. Thankfully, the eruptions have not been very explosive so that few people have been killed. But the lavas destroy the use of the land, and since the Cape Verde Island people make only about $1000/yr, any reduction in income is very serious.