Mount Semeru Volcano Restive, Alert Level III
May 22, 2008
Jakarta – Indonesian authorities on Thursday urged residents living around the slopes of Mount Semeru in Indonesia’s crowded East Java province to keep their distance from the active volcano, which appears to be heating up.
Vulcanologists upgraded the alert status of Mount Semeru volcano to level three, one level below a full state of alert, after the 3,676-metre-high volcano on Wednesday sent hot lava as much as 3,000 metres down its slopes.
Villagers and farmers were urged ‘not to conduct activity at a radius of 4 kilometres from the crater, especially around the south-east of the volcano’s slopes,’ said Surono, head of Indonesia’s Centre for Volcanology and Geological Hazard Mitigation at the directorate general of volcanology.
Surono, who like many Indonesians goes only by one name, appealed to residents living on the riverbanks along three different rivers to be cautious of threats posed by lava streams.
However, no immediate evacuation is being considered for residents living in a number villages in the potential danger zone, he said, adding that a team of experts is intensively monitoring Mount Semeru’s activity round-the-clock.
The Mount Semeru volcano, 780 kilometres east of Jakarta, is a popular tourist destination, especially for hikers. Semeru is one of Indonesia’s most active volcanoes.
The Indonesian archipelago, straddling the seismically active ‘Ring of Fire,’ has the world’s highest density of volcanoes. Of its 500 volcanoes, 128 are active and 65 are listed as dangerous. (Source) Copyright respective author or news agency.

The climb to the summit of Semeru is a 2-3 day walk. The mountain stages minor eruptions (like in the photograph) every 20 – 40 minutes. The photo was taken in late afternoon (August 2003) and simply involved walking from the campsite at the base of the climb to the summit around to the west so that the sun was at my back, then waiting for the eruption to start. The most striking aspect of the photo is the colour caused by the almost perpendicular rays of the sun hitting the cloud of dust and steam escaping a couple of thousand metres into the sky from the crater. The photo typifies the fact that Indonesia sits in the middle of the “Ring of Fire”. The many spectacles presented by the landscapes, the festivals and the people of Indonesia never cease to truly amaze me. Photo and caption credit: Campbell Bridge (via Trek Earth at:http://www.trekearth.com/gallery/Asia/Indonesia/photo109462.htm)

Semeru: The Most Active Volcano of Java
Semeru also Gunung Semeru is the highest and one of most active volcanoes of Java. Known also as Mahameru (Great Mountain), it is very steep and rises abruptly above the coastal plains of eastern Java. Maars containing crater lakes have formed along a line through the summit. Semeru lies at the south end of the Tengger Volcanic Complex. The steep-sided volcano, also referred to as Mahameru (Great Mountain), rises abruptly to 3676 m above coastal plains to the south. Semeru’s eruptive history is extensive. Since 1818, at least 55 eruptions have been recorded (10 of which resulted in fatalities) consisting of both lava flows and pyroclastic flows. More than 500 people have been killed by Semeru’s eruptions during the last 30 years. Semeru has been in almost continuous eruption since 1967. (Source 1 and 2 )

Semeru is one of many volcanoes in the Pacific Ring of Fire. Graphic courtesy of Darwin VAAC.

Semeru, a stratovolcano, has erupted at least 55 times since 1818. The eruptions are commonly moderate to moderately large (VEI of 2 to 3) and explosive. This photo, taken November 4, 1982, shows a small cloud associated with a Strombolian eruption (relatively low-level volcanic eruptions) . Photo by Jack Lockwood, U.S. Geological Survey. (Source)

Strombolian eruptions are relatively low-level volcanic eruptions, named after the Italian volcano named Stromboli, where such eruptions consist of ejection of incandescent cinder, lapilli and lava bombs to altitudes of tens to hundreds of meters. They are small to medium in volume, with sporadic violence. (Source). Credit: Wolfgang Beyer GNU Free Documentation license, Version 1.2 or any later version published by the Free Software Foundation.
Semeru eruptions are commonly moderate to moderately large (VEI of 2 to 3). Some of the eruptions produced lahars (a type of mudflow composed of pyroclastic material and water that flows down from a volcano). Semeru’s most recent eruption began in 1967 and has continued to the present. In August of 1994, explosions occurred at 15-20 minute intervals. In February of 1995, pyroclastic avalanches traveled about 0.6 mile (1 km) from the summit.

Semeru, 1985. A USGS Photo.
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