Ijen

Located in a densely populated area in East Java, it is the boundary of 2 counties: Bondovoso and Banyuvangi . The nearest large settlement is located to the south-east of the volcano - Banuvangi . About 12,000 people live in the vicinity of the volcano itself. This volcano is a complex consisting of more than a dozen volcanic objects: stratovolcanoes , volcanic cones , craters located within a radius of 20 km around the caldera ^[2] . In the caldera is located the sulfurous lake Kawah Ijen , the water in the lake has a turquoise hue. The caldera is 200 meters deep and 1 km wide. The shores of the lake are natural large deposits of natural sulfur. In the period from 1922 to 1996, the volume of the lake decreased from 0.044 to 0.0036 km³.

The highest point of the volcanic complex is Merapi stratovolcano, reaching a height of 2803 meters, located on the southeast slope of the caldera. The largest number of volcanic structures is located on the south side of the caldera. At the northern end of the caldera, objects form an arcuate ridge. The subduction zone is more than 25 km. Initially, during the Pleistocene epoch , a caldera was formed, later Merati stratovolcano and other volcanic cones appeared around it. It consists mainly of basalts , basalt andesites , andesites , picrobasalts , and to a lesser extent dacites . The most active are stratovolcano Raung, releasing plumes of steam, and Lake Kawah. Fumarolic activity is constantly taking place on the lake. It is sulphate-chloride in composition and has a high acidity. Kawah has a low ph that does not exceed a value of 0.2. The temperature of nearby hydrothermal springs and the lake itself is 170-245 ° C (the boiling point of a mixture of sulfuric and hydrochloric acid of the lake). The surface temperature is 50-60 ° C. In the modern period, the volcano erupted significantly more than a dozen times, the maximum scale of volcanic activity was 2. Volcanic eruptions had different phreatomagmatic , phreatic , strombolian and plinian types of eruptions, which manifested themselves from more than 22 separate volcanic faults . Most often manifested phreatic type of eruption . A volcano is a danger of gathering lahars , pyroclastic flows , lava flows . The last significant eruption occurred from 4 to 25 November 1936. Then the epicenter of the eruption was located directly in the caldera itself. Activity was quite high, as water flows overflowed from the west side of the caldera. The most disastrous was the volcanic activity that occurred in 1817 and lasted 33 days. Then the waters of Lake Kawah overflowed due to the collapse of the slopes of the main caldera and flooded nearby villages and fields with mudflows . 3 villages were damaged, more than 90 houses were destroyed, there were casualties among the population ^[3] . The last slight activity was shown from July 29 to August 15, 2002. Then there was a slight explosion and the emission of streams of burning ash over short distances.

Ijen is very popular among tourists. Tourists come to visit the crater of the volcano, sulfur lake, to see the traditional process of sulfur extraction. Also, the volcano is surrounded by waterfalls, hot springs and volcanic landscapes, which were formed during the active activity of the volcano.

At the eruption site, locals mine sulfur manually with hammers and make their way on foot for about 3 km to the local Jambu plant located in the south-east of the volcano. Sometimes baskets with pieces of sulfur reach 80 kg. The slopes leading to the base of the caldera are covered with coffee plantations.

In one of the craters of the volcano, an unusual natural phenomenon occurs, the exit to the surface of blue volcanic gases ^[5] . This phenomenon occurs because of the ignition of hydrogen sulfide with a temperature of 600 ° C, which is the cause of this color. The glow is weak, so the flame can be seen only at night. Some of the gas condenses and forms stalactites of pure sulfur, which is also mined by local residents and offered as a souvenir to tourists.

A slight activity is constantly recorded on the volcano: a change in the color of Lake Kavah from green to white, whitish green to brown; foam formation due to sulfuric gas activity; minor tremors that reach several hundred per year; fumarol vapors changing color from white to brownish white.

Currently, the volcano is active in the form of minor fumaroles and minor tremors. In the period from August 6 to 14, 2014, the alert level reached 1. Local station of the center of volcanology and geological activity of Indonesia did not recommend tourists and locals to visit the surroundings of the volcano ^[6] .

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  3D modeling of a volcanic complex

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  Volcanic lake Kawah

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  Stratovolcano Merapi

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  Sunset in the area of ​​Igen

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  Manual sulfur extraction

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  Sulfur Porter in the crater of a volcano

• Harun Taziev . On the volcanoes. - Moscow: World , 1987. - 263 p.

• Ijen : [ eng ] // Global Volcanism Program . - Smithsonian Institution . - Date of appeal: 08/24/2014
• Volcano Live - John Search (eng.) . The appeal date is August 24, 2014.