Mount Semeru or Mount Meru is a conical volcano in East Java, Indonesia. Mount Semeru is the highest mountain on the island of Java, with a peak of Mahameru, 3,676 meters above sea level (masl). This mountain was formed due to the subduction of the Indo-Australian Plate under the Eurasian Plate. Mount Semeru is also the third highest volcano in Indonesia after Mount Kerinci in Sumatra and Mount Rinjani in West Nusa Tenggara. The crater at the top of Mount Semeru is known as Jonggring Saloko.
Mount Semeru is administratively included in the area of two regencies, namely Malang Regency and Lumajang Regency, East Java Province. This mountain is included in the Bromo Tengger Semeru National Park area. Semeru has Dipterocarp Hill forest areas, Upper Dipterocarp forests, Montane forests, and Ericaceous Forests or mountain forests. Semeru's geographical position is between 8°06' latitude and 112°55' east longitude.
In 1913 and 1946 Jonggring Saloka Crater had a dome with a height of 3,744.8 m until the end of November 1973. To the south, this dome smashed into the crater rim causing lava flows towards the south side covering the Pronojiwo and Candipuro areas in Lumajang.
This mountain is included in the Bromo Tengger Semeru National Park area. This National Park consists of mountains and valleys covering an area of 50,273.3 hectares. There are several mountains within the Mount Tengger Caldera, including: Mount Bromo (2,392 m); Mount Batok (2,470 m); Seat Mountain (2,581 m); Mount Watangan (2,662 m); and Mount Widodaren (2,650m). There are four lakes (ranu): Ranu Pani, Ranu Regulo, Ranu Kumbolo and Ranu Darungan.
There are various types of flora in the Mount Semeru area but are mostly dominated by spruce, acacia, pine, and Jamuju species. Meanwhile, the undergrowth is dominated by kirinyuh, reeds, tembelekan, harendong and white edelwiss. Edelwis is also commonly found on the slopes leading to the summit of Semeru. There is also an endemic species of orchid that lives around the southern part of Mount Semeru, namely the Slipper Orchid.
Many fauna that inhabit Mount Semeru include: panthers, budeng, mongoose, deer, deer, etc. Meanwhile, at Ranu Kumbolo there are grouses that still live wild.
First climber
The first Europeans to climb this mountain were Clignet and Winny Brigita (1838), a Dutch geologist. They took the route from the southwest via Widodaren. Then Junghuhn (1945), a Dutch botanist, climbed from the north via Mount Ayek-ayek, Mount Inder-inder and Mount Kepolo. In 1911, Van Gogh and Heim went through the northern slopes and after 1945 generally climbing was done via the northern slopes through Ranu Pani and Ranu Kumbolo until now.
Poison gas
At the top of Mount Semeru (Puncak Mahameru) climbers are advised not to go to the Jonggring Saloko crater, also prohibited from climbing from the south side, due to the presence of toxic gases and lava flows. This poisonous gas is known as Wedhus Gembel (Javanese which means "dreadlocks goat", which is a goat that has hair like dreadlocks) by local residents. The temperature at the peak of Mahameru ranges from 4-10 degrees Celsius, at the peak of the dry season minus 0 degrees Celsius, and ice crystals are found. The weather is often foggy, especially in the afternoon, evening and night. The wind is blowing hard, in December - January there are often storms.
Wedus Gembel eruptions occur every 15-30 minutes at the peak of Mount Semeru which is still active. In November 1997, Mount Semeru erupted 2990 times. During the day, the wind direction is towards the peak, so avoid coming during the day at the peak, because toxic gases and eruptions lead to the peak.
The eruption was in the form of white, gray to black smoke with an eruption height of 300-800 meters. The material that comes out in each eruption is in the form of ash, sand, gravel, and even hot burning stones which are very dangerous if climbers are too close. In early 1994 hot lava flowed down the southern slopes of Mount Semeru and had claimed several lives, although the view of the hot river winding towards the sea is a very interesting spectacle.
The eruption in early January 2021 resulted in the population of 5 sub-districts on the slopes of Semeru; Candipuro District, Pasrujambe District, Senduro District, Gucialit District, and Pasirian District. The PVMBG appealed to the public not to carry out activities within a 1 km radius of the summit crater of Mount Semeru and a distance of 4 km to the crater opening in the south-southeast sector, and to be aware of hot clouds falling, lava avalanches, and lava along rivers/valleys flowing through the river. originates at the top of Mount Semeru. The radius and distance of this recommendation will be evaluated continuously to anticipate if there are symptoms of changes in the threat of danger.
Soe Hok Gie, one of the prominent Indonesian activists and a student of the Faculty of Letters at the University of Indonesia, died on Mount Semeru in 1969 as a result of inhaling toxic fumes on Mount Semeru. He died with his colleague, Idhan Dhanvantari Lubis.
Eruption activity
1800's
The first recorded eruption was estimated at 8 November 1818. In the 1829-1878 range there were also several eruptions until 1913 but not much documented information. Eruptions in the 19th century AD occurred in 1829, 1830, 1832, 1836, 1838, 1842, 1844, 1845, 1848, 1851, 1856, 1857, 1860, 1864, 1867, 1872, 1877, and 1878. it erupted again in 1884 to 1899.
1900's
In 1941-1942, long duration volcanic activity was recorded. The Center for Volcanology and Geological Hazard Mitigation (PVMBG) stated that the lava flow occurred in the period from September 21, 1941 to February 1942. At that time, the eruption reached the eastern slope with a height of 1,400 to 1,775 meters. Volcanic material to pile up the Bantengan irrigation post.
Several volcanic activities were also recorded in succession in 1945, 1946, 1947, 1950. They erupted again in succession from 1951 to 1961 and 1963. Successive eruptions occurred again from 1967 to 1969 and 1972 to 1990. The next eruption was followed in in 1992 and 1994. The eruption in 1994 was horrific because it claimed the lives of 7 people and people were swept away by the lava.
On December 1, 1977, a lava avalanche produced hot clouds of avalanches with a distance of up to 10 km in Besuk Kembar. The observed volume of volcanic material deposits reached 6.4 million cubic meters. Hot clouds also point to the Besuk Kobokan area. At that time, rice fields, bridges and residents' houses were damaged. Volcanic activity continued and was recorded in 1978–1989.
On February 2, 1994, there were 9 eruptions of Mount Semeru. This eruption resulted in the emergence of thick white smoke with a height of up to 500 meters. In addition to white smoke, there were 34 lava avalanches in the direction of Besuk Twins as far as 1 km. The eruption of Mount Semeru claimed the lives of 7 people who were swept away by the lava.
2000s
PVMBG also recorded volcanic activity of this mountain in 1990, 1992, 1994, 2002, 2004, 2005, 2007 and 2008. In 2008, several eruptions were recorded, namely in the range of 15-22 May 2008. Observed on 22 May 2008, four avalanches were recorded. hot clouds that lead to the Besuk Kobokan area with a sliding distance of 2,500 meters.
On June 12, 2006, the Tanjung Perak Maritime Meteorology and Geophysics Agency (BMKG) recorded a volcanic earthquake with a magnitude of 1.8 on the Richter Scale (SR) due to the activity of Mount Semeru (3,676 masl).
On December 1, 2020, Mount Semeru experienced an eruption which was followed by hot clouds falling from the summit. The sliding distance of this hot cloud is 2-11 kilometers.
Until December 4, 2021 at 15.10 WIB, Mount Semeru erupted and released a hot cloud of avalanches leading to Besuk Kobokan, Sapitarang Village, Pronojiwo District, the last and most recent eruption in a number of BNPB. The lava fall traveled with a sliding distance of 500-800 meters, with the center of the fall 500 meters below the crater. Meanwhile, volcanic earthquakes related to eruptions, avalanches and gusts of crater smoke have occurred as many as 54 earthquakes or eruptions, 4 earthquakes avalanches, and 18 times earthquake gusts.
Vegetation
Non-native invasive plant
25 non-native plants have been found in Gunung Semeru National Park. this non-native plant, which threatens endemic to this local plant, was imported by the Dutch botanist Van Steenis, in the colonial era. They include Foeniculum vulgare, Verbena brasiliensis, Chromolaena odorata, and Salvinia molesta.
Vegetable garden
Mud erosion from the surrounding vegetable plantations adds silt to Lake Ranu Pani, causing the lake to gradually shrink. Research has predicted that the lake will disappear around 2025, unless hillside vegetable plantations are replaced with more ecologically sustainable perennials.
