The Ijen volcano complex is a
group of composite volcanoes in the Banyuwangi Regency of East Java, Indonesia.
It is inside a larger caldera Ijen, which is about 20 kilometres wide. The
Gunung Merapi stratovolcano is the highest point of that complex. The name
"Gunung Merapi" means "mountain of fire" in the Indonesian
language (api being "fire"); Mount Merapi in central Java and Marapi
in Sumatra have the same etymology.
West of Gunung Merapi is the Ijen
volcano, which has a one-kilometre-wide turquoise-coloured acidic crater lake.
The lake is the site of a labor-intensive sulfur mining operation, in which
sulfur-laden baskets are carried by hand from the crater floor. The work is
paid well considering the cost of living in the area, but is very onerous.[2]
Workers earn around Rp 50,000–75,000 ($5.50–$8.30) per day and once out of the
crater, still need to carry their loads of sulfur chunks about three kilometers
to the nearby Paltuding Valley to get paid.[3]
Many other post-caldera cones and
craters are located within the caldera or along its rim. The largest
concentration of post-caldera cones run east-west across the southern side of
the caldera. The active crater at Kawah Ijen has a diameter of 722 metres
(2,369 ft) and a surface area of 0.41 square kilometres (0.16 sq mi). It is 200
metres (660 ft) deep and has a volume of 36 cubic hectometres (29,000 acre·ft).
The lake is recognized as the
largest highly acidic crater lake in the world.[1] It is also a source for the
river Banyupahit, resulting in highly acidic and metal-enriched river water
which has a significant detrimental effect on the downstream river ecosystem.[4]
On July 14–15, 2008, explorer George Kourounis took a small rubber boat out
onto the acid lake to measure its acidity. The pH of the water in the lake's
edges was measured to be 0.5 and in the middle of the lake 0.13 due to high
sulfuric acid concentration.
Since National Geographic
mentioned the electric-blue flame of Ijen, tourist numbers increased.[6] The
phenomenon has occurred for a long time, but beforehand there was no midnight
hiking. A two-hour hike is required to reach the rim of the crater, followed by
a 45-minute hike down to the bank of the crater. The blue fire is ignited
sulphuric gas, which emerges from cracks at temperatures up to 600 degrees
Celsius.
An active vent at the edge of the
lake is a source of elemental sulfur, and supports a mining operation. Escaping
volcanic gases are channeled through a network of ceramic pipes, resulting in
condensation of molten sulfur.[9] The sulphur, which is deep red in color when
molten, pours slowly from the ends of these pipes and pools on the ground,
turning bright yellow as it cools. The miners break the cooled material into
large pieces and carry it away in baskets. Miners carry loads ranging from 75
kilograms (165 lb) to 90 kilograms (200 lb), up 300 metres (980 ft) to the
crater rim, with a gradient of 45 to 60 degrees and then 3 kilometres (1.86
miles) down the mountain for weighing. Most miners make this journey twice a
day. A nearby sulfur refinery pays the miners by the weight of sulfur
transported; as of September 2010, the typical daily earnings were equivalent
to approximately $13 US. The miners often receive insufficient protection while
working around the volcano [10] and complain of numerous respiratory
afflictions. There are 200 miners, who extract 14 tons per day – about 20
percent of the continuous daily deposit.
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