The formation of Ijen Plateau and Ijen crater lake
Indonesia is famous for hosting some of the world's most powerful volcanoes. Ijen crater lake is the most amazing Indonesian lake, representing a solution of sulphuric acid and hydrogen chloride, the most powerful existing acids. The lake contains 600,000 tonnes of hydrogen chloride, 550,000 tonnes of sulphuric acid, 200,000 tonnes of aluminium sulphate and 170,000 tonnes of iron sulphate, with an acidity around pH 0.5. Any eruption through this lake would expel the water and create deadly mudflow that can claim hundreds of lives and properties.
| Indonesia is famous for hosting some of the world's most powerful volcanoes. Ijen crater lake is the most amazing Indonesian lake, representing a solution of sulphuric acid and hydrogen chloride, the most powerful existing acids. The lake contains 600,000 tonnes of hydrogen chloride, 550,000 tonnes of sulphuric acid, 200,000 tonnes of aluminium sulphate and 170,000 tonnes of iron sulphate, with an acidity around pH 0.5. Any eruption through this lake would expel the water and create deadly mudflow that can claim hundreds of lives and properties. |
Pre- and post-caldera activity of Ijen
Pre-caldera activity of the Ijen crater complex is supposed to have started prior to 300,000 years ago. It probably formed a large single stratovolcano - Old Ijen - with an estimated altitude of 3500 m. The caldera formation is associated with the eruption of a large volume – around 80 cubic kilometres - of pyroclastic flow deposits. These are waves that consist of solid or semi-liquid lava, gas, rocks and ash. They can reach temperatures up to about 850 °C and can reach a speed to around 725 km/h. The event occurred some time before 50,000 years ago. This is based on analysis of a lava flow of Mt. Blau. Mt. Blau is considered to be the oldest post-caldera unit.
Post caldera activity produced the rim cones and the inner cones. These younger volcanoes produced the ash and scoria cones, lava flows, pyroclastic flow and surge deposits and debris avalanche material that now cover the caldera flow.
| Pre-caldera activity of the Ijen crater complex is supposed to have started prior to 300,000 years ago. It probably formed a large single stratovolcano - Old Ijen - with an estimated altitude of 3500 m. The caldera formation is associated with the eruption of a large volume – around 80 cubic kilometres - of pyroclastic flow deposits. These are waves that consist of solid or semi-liquid lava, gas, rocks and ash. They can reach temperatures up to about 850 °C and can reach a speed to around 725 km/h. The event occurred some time before 50,000 years ago. This is based on analysis of a lava flow of Mt. Blau. Mt. Blau is considered to be the oldest post-caldera unit. Post caldera activity produced the rim cones and the inner cones. These younger volcanoes produced the ash and scoria cones, lava flows, pyroclastic flow and surge deposits and debris avalanche material that now cover the caldera flow. |
Ijen's landscape full of volcanic cones
The Ijen Plateau was at one time a huge active crater complex of 134 square kilometres in area. Nowadays, the large caldera complex hosts a large number of volcanic edifices of which Ijen and Raung are the most active. The Ijen caldera has a diameter of about 14-16 km.
The landscape is dominated by the volcanic cones of Ijen (2368 m) and Merapi (2800 m) on the north-eastern edge of the plateau, and Raung (3332 m) on the south-western corner. The Ijen crater stands inside the caldera, while Merapi and Raung have arisen along a ring fracture at the edge of the caldera. The caldera’s northern margin is clearly visible as a typical caldera escarpment with a steep inner slope and elevations ranging from 850 to 1559 m.
The southern and eastern walls are covered by the marginal volcanoes of Suket (2950 m), Jampit/Pendil (2338 m), Rante (2644 m), Merapi (2799 m), Ijen (2386 m), Pawenen (2123 m) and Ringgih (1965 m). Inside the caldera the topography is dominated by a large number of extinct volcanic cones: Cilik (1872 m), Pendil (2375 m), Anyar (1276 ), Genteng (1712 m), Gelaman (1726 m), Kukusan (1994 m), Papak (2099 m), idodaren (2100 m), Blau (1774 m), Gendingwaluh (1519 m), Lingker (1630 m) and Kunci (1788 m).
| The Ijen Plateau was at one time a huge active crater complex of 134 square kilometres in area. Nowadays, the large caldera complex hosts a large number of volcanic edifices of which Ijen and Raung are the most active. The Ijen caldera has a diameter of about 14-16 km. The landscape is dominated by the volcanic cones of Ijen (2368 m) and Merapi (2800 m) on the north-eastern edge of the plateau, and Raung (3332 m) on the south-western corner. The Ijen crater stands inside the caldera, while Merapi and Raung have arisen along a ring fracture at the edge of the caldera. The caldera’s northern margin is clearly visible as a typical caldera escarpment with a steep inner slope and elevations ranging from 850 to 1559 m. The southern and eastern walls are covered by the marginal volcanoes of Suket (2950 m), Jampit/Pendil (2338 m), Rante (2644 m), Merapi (2799 m), Ijen (2386 m), Pawenen (2123 m) and Ringgih (1965 m). Inside the caldera the topography is dominated by a large number of extinct volcanic cones: Cilik (1872 m), Pendil (2375 m), Anyar (1276 ), Genteng (1712 m), Gelaman (1726 m), Kukusan (1994 m), Papak (2099 m), idodaren (2100 m), Blau (1774 m), Gendingwaluh (1519 m), Lingker (1630 m) and Kunci (1788 m). |
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