At least three of the many volcanoes in Indonesia are called Merapi, meaning 'mountain of fire'. The best-known is the 9,737-foot high Merapi in the center of the island of Java, one of the most dangerous of the nation's 129 volcanoes. More than one million people live in the immediate area, and the city of Yogyakarta, Indonesia's cultural capital, is only 18 miles away.
What makes this stratovolcano so dangerous is the plug of hot rock slowly pushing out of its vent, creating a lava dome. Pieces of rock break off from it and crash down the flanks of the volcano. By day, these falling rocks can usually only be heard, but at dusk the glowing pieces of lava that bounce down the slope and explode become visible. Whole families travel to the observatory in Babadan, just 3 miles from the summit as the crow flies, to witness the fireworks.
However, every few years the lava dome collapses. People in the immediate danger zone are evacuated as clouds of ash shoot out of the crater and pyroclastic flows charge down the slopes. During the rainy season these fresh emissions can turn into potentially dangerous lahars and mudslides.
Photo credit: Bernhard Edmaier