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http://volcano.und.nodak.edu/vwdocs/volc_images/southeast_asia/merapi.htmlMerapi, Java, Indonesia

Location: 7.5S, 110.4EElevation: 9,548 feet (2,911 m)Last Updated: 29 December 2000More Information Top of Form

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Merapi is a stratovolcano in central Java. Merapi has had 68 historic eruption since 1548. The current eruption began in 1987. Because of Merapi's violent past and its close proximity to Yogyakarta it was designated a Decade Volcano and is the target of increased research efforts. Photo by Jack Lockwood, U.S. Geological Survey, September 6, 1982.

Merapi is a stratovolcano with an active summit lava dome. It is located ~30 km immediately north of Yogyakarta, a city with a population of 500,000. Merapi has the unfortunate distinction of producing more nuee ardentes than any other volcano on Earth. The nuee ardentes result from collapse of the lava dome at the summit. Of the 67 historic eruptions 32 have had nuee ardentes associated with them. Eleven of these eruptions resulted in fatalities. Merapi is closely monitored by the Volcanological Survey of Indonesia. Shortly before this photograph was taken Merapi was generating up to 40 nuee ardentes per day. Photograph by Robert Koyanagi, U.S. Geological Survey, July 28, 1979.

Rockfall from the collapse of a lava dome. Photo by Jack Lockwood, U.S. Geological Survey, September 8, 1982.

Lava dome at the summit of Merapi. During 1982, the lava dome was growing about 80,000-100,000 cubic meters per month. The dome collapsed in late November, creating nuee ardentes. Photo by Jack Lockwood, U.S. Geological Survey, October 17, 1982.

Pyroclastic flow deposit on Merapi. Photo by Jack Lockwood, U.S. Geological Survey, November 2, 1982.

Kadong school is in the lower left of this photo. Barriers (just left of the stream valley) have protected the school from lahars. In 1979, heavy rainfall mobilized old lahar deposits to create landslides that travelled as far as 12 miles (20 km) downslope. Eighty people were killed. Photo by Jack Lockwood, U.S. Geological Survey, September 26, 1982.

In late November of 1994, collapse of a lava dome at Merapi generated pyroclastic flows and surges that travelled as far as 5 miles (7.5 km) from the summit. The flows and surges killed 43 people. The plume associated with the dome collapse rose 6 miles (10 km) above the volcano. Over 6,000 people were evacuated. The eruption also started fires.

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Sources of Information:

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

Smithsonian Institution's Global Volcanism Network, 1995, Summary of Recent Activity: Bulletin of Volcanology, v. 57, p. 73-75.

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Incandescent rocks tumbling down the south flank of Merapi in August of 1996. Copyrighted photo by Nick Varley.

View of Merapi in August 1996 from the look-out tower at Ngadas Volcanic Observatory. A lava dome can be seen which had been steadily growing since the previous year. Copyrighted photo by Nick Varley.

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View looking south-southwest along the path to the summit of Merapi. Photo by Steve Mattox, December 9, 1997.

View looking south-southwest to the summit of Merapi. This part of the summit is made of the 1953, 1954, and 1956 lava domes. Photo by Steve Mattox, December 9, 1997.

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Galunggung, Java, Indonesia

Location: 7.3S, 108.1EElevation: 7,111 feet (2,168 m)

Galunggung is a stratovolcano on the west side of the island of Java. The caldera of Galunggung is open to the southeast. Photo by Jack Lockwood, U.S. Geological Survey, August 17, 1982.

The first historic eruption of Galunggung was in 1822. Since then the volcano has erupted four times, most recently in 1984. This photo shows a column of ash rising above the summit during the large (VEI=4) Vulcanian-type eruption. Eruption columns at Galunggung reached heights as great as 15 miles (24 km). Photo by Jack Lockwood, U.S. Geological Survey, August 16, 1982.

Two eruptions at Galunggung have caused fatalities. During the 1822 eruption (VEI=5), nuee ardentes and mudflows killed 4,011 people and destroyed 114 villages. The nuee ardentes extended up to 6 miles (10 km) away from the volcano. During the 1982 eruption (VEI=4) about 68 people died, mostly from indirect causes (traffic accidents, old age, cold, and lack of food). Estimated damage was $15 million and 22 villages were left uninhabitable. The 1984 eruption was phreatic and lasted about two weeks. This photo shows lightning above the summit and glowing pyroclasts on the flank of Galunggung. Photo by Jack Lockwood, U.S. Geological Survey, September 16, 1982.

The April 1982-January 1983 eruption destroyed the 1918 lava dome and produced a new cinder cone in a new crater. The crater was about 2,000 feet (600m) across and about 1,000 feet (300 m) deep. The cone grew to 250 feet (75 m) and was 650 feet (200 m) in diameter. Photo by Jack Lockwood, U.S. Geological Survey, July 31, 1982.

View of new cinder cone. As the 1982-1983 eruption waned a crater lake began to form. The presence of the lake, high rainfall, and the large volume of exposed pyroclastic material on the volcano have made the hazard associated with secondary lahars very high. The lahar deposits have been revegitated and a lahar warning system has been established. Photo by Jack Lockwood, U.S. Geological Survey, October 30, 1982.

During the 1982 eruption two jumbo jets entered the ash clouds at an altitude of about 6 miles (10 km). Their engines stalled and windshields were abraded. Fortunately, the pilots were able to restart the engines.

Source of Information:

Lubis, H., Hamidi, S., and Casadevall, T., 1987, Volcanic hazards at Galunggung, West Java, Indonesia, since the 1982-1982 eruption: Hawaiian Symposium on How Volcanoes Work, abstract volume, p. 160.

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

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Tangkubanparahu Volcano, Island of Java

Location: 6.77S, 107.60EElevation: 6836 ft (2084 m)Last update: October 30, 2002

Tangkubanparahu is an active stratovolcano within the Sunda Caldera, west Java. Tangkubanparahu has erupted about seventeen times since 1826. The city of Bandung, population 1.6 million, is 18 miles (30 km) south of the volcano. This photograph shows Ratu fumarole field and crater. The most recent activity at this vent was a small phreatic eruption in 1983. Photograph by John Dvorak, U.S. Geological Survey, March 16, 1982.

A view into the crater of Tangkubanparahu. Copyrighted photo by Nick Varley.

Another view into the crater of Tangkubanparahu. Copyrighted photo by Nick Varley.

October 15, 2002

Seismicity has been dominated by volcanic events from Sept. 9 - Oct. 6. Thin ash plumes rose 2.5 km above the volcano. The volcano remained at alert level 2.

This information was summarized from the GVP/USGS Weekly Volcanic Activity Report

September 17, 2002Following the increase of seimic activity and temperatures of Domas and Ratu craters in the last two weeks (2-4C increase) , the Alert Level was increased to 2 (on scale 1-4). No changes were observed on the volcano surface, but several animals were found dead in the crater.

This information was summarized from the GVP/USGS Weekly Volcanic Activity Report

Sources of Information:

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, AZ, 349 p.

McClelland, L., Simkin, T., Summers, M., Nielsen, E., and Stein, T.C., 1989, Global Volcanism 1975-1985, Prentice Hall, Englewood Cliffs, New Jersey, 655 p.

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Lavas and Pyroclastic Rocks

Lavas

Basaltic lavas are thin and fluid and come in two varieties: pahoehoe and aa. Pahoehoe has a characteristic smooth, ropy surface; aa is jagged, cindery, and very difficult to walk upon. Aa forms from slightly more viscous magma than pahoehoe. Columnar jointing is common in basalt flows. More silicic lavas are called block lavas and form as a viscous lava flow fragments upon flowing.

Pahoehoe on Mauna Loa

Smooth-sided basaltic vent on Mauna Loa

Hornito on aa flow, Lava Beds National Monument

Columnar jointing in the Devils Postpile, California

Margin of Obsidian Dome, California

Obsidian and interfingered pumice at Obsidian Dome

Tuff from eruption of Mt. Mazama (Crater Lake)

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