Dust clouds rise from Fernandina caldera on July 4, 1968, about three weeks after a major explosive eruption that was followed by collapse of the caldera floor. Collapse occurred incrementally and asymmetrically, ranging up to about 350 m at the SE end of the caldera, which contains the caldera lake. Fernandina, the most active of Galápagos volcanoes, is a basaltic shield volcano with a deep 4 x 6.5 km summit caldera. Flat-topped benches mark the SE and NW ends of the elliptical caldera. Photo by Tom Simkin, 1968 (Smithsonian Institution).
Chuck Wood took this picture in 1979 while sailing around Fernandina island.
The lava flows are clearly seen on the sides of the volcano and along the shore.
The Jan-Feb, 1995 eruption:
On Jan 25, sailors reported a red glow over Fernandina, the most active of The Galapagos volcanoes. A group of interested people immediately set sail to Fernandina and discovered that lava was flowing from a crack in the ground (such cracks are called fissures). The new lava flowed about five kilometers and entered the sea. By the 28th of September, small clots of lava thrown up around the fissure had built a spatter cone 20-30 m high. A plume or cloud of steam and ash particles rose 3-4 km above the cone.
Observations of a red glow over the caldera at the top of Fernandina during the first night, and later discovery of other fissures and fresh lava between the spatter cone and the caldera suggests a story for how the eruption developed. Perhaps the eruption started inside the caldera (explaining the red glow seen early on). Then a crack or fracture allowed lava to escape along the line of fissures. Finally, the eruption concentrated at the lower fissure where a cone was built. And lava continued to pour into the sea at least until mid-February.
This picture of Fernandina was taken by a Space Shuttle crew in the 1980s. Everything on the island is volcanic - the lava flows are shades of blue. The X on the bottom left side shows the approximate location of the 1995 eruption site. One of the sad things about the eruption is that many birds and fish were killed. The heat from the lava entering the sea killed fish, and then seabirds who dived into the water to eat the fish were scalded to death.
Background on the Galapagos Islands
A thousand kilometers west of Ecuador is a volcanic chain called the Galapagos Islands. These Pacific Ocean islands are famous because the British scientist Charles Darwin visited them in the 1830s. It was Darwin's studies of the Galapagos finches and other birds and animals that led him to his famous theory of evolution.
Although the Galapagos includes nearly a dozen islands, most of the volcanic activity during the last few hundred years has occurred on two islands, Isabela and Fernandina. Isabela is shaped like a seahorse and contains five and a half large shield volcanoes. The half volcano is Ecuador (the name of a volcano, not the country!), whose western half has apparently collapsed into the ocean.
The Galapagos Islands have been built entirely by volcanism, and about 60 previous eruptions have been recorded over the last 200 years, so it is not surprising that another eruption has occurred. But the surprise is where the eruption happened. Although many Galapagos eruptions have been in and around the large calderas on top of the shield volcanoes, the activity that started Jan 25 was from a vent far down the flank of Fernandina, near the sea. The last time this occurred at Fernandina, in 1968, there was a huge collapse of the floor of the caldera - it fell more than 350 meters. The new eruption has not caused another collapse, so far.
Chuck Wood took this picture in 1979 also. It shows the small boat they used to sail around the islands. At the helm is Tui De Roy, a woman who grew up in the Galapagos Islands and knows them probably better than any other person. The two bearded men behind her who look like fishermen are actually famous volcanologists. The man on the right is Bob Smith of the U.S. Geological Survey, and the man on the left is Tom Simkin of the Smithsonian Institution.