The Long History of Mount Semeru Eruptions

Nusantara Pol - On Saturday afternoon (4/12/2021), Mount Semeru in the East Java Province, Indonesia, spewed hot cloud avalanches. The volcanic material, which was first observed at 15.20 WIB, falls in the direction of Besuk Kobokan, Sapitarang Village, Pronojiwo District, Lumajang.

From National Agency for Disaster Management website, the record of Mount Semeru eruptions can be traced back to 1818.

Thick volcanic cloud as a result of Mount Semeru Explosion. (Photo: BNPB)

However, from 1818 to 1913 the record does not document many volcanic activities. Then in 1941-1942 significant volcanic activities were 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.

More volcanic activities were recorded in succession in 1945, 1946, 1947, 1950, 1951, 1952, 1953, 1954, 1955 – 1957, 1958, 1959, 1960.

Then, on December 1, 1977, Mount Semeru erupted once again and spewed lava and hot clouds avalanches with a distance of up to 10 km in Besuk Kembar.

The observed volume of volcanic material deposits reached 6.4 million m3. Hot clouds also launched to the Besuk Kobokan area. At that time rice fields, bridges and houses were damaged.  Volcanic activities continued and were recorded in 1978 – 1989.

PVMBG also recorded Semeru volcanic activity in 1990, 1992, 1994, 2002, 2004, 2005, 2007, and 2008.

In 2008, several eruptions were recorded, namely between May 15 to May 22, 2008. Observed on May 22, 2008, four hot cloud avalanches fell to the Besuk Kobokan area with a sliding distance of 2,500 meters.

According to PVMBG data, the main activity of Mount Semeru is in the Jonggring Seloko crater. This crater is located on the southeast side of the peak of Mahameru, the other name of Semeru. 

The eruption of Mount Semeru is categorized as Vulcanian and Strombolian type which occurs 3-4 times every hour. The character of a Vulcanian eruption is in the form of an explosive eruption that can destroy a previously formed lava dome and tongue. Meanwhile, the character of a Strombolian eruption is usually the formation of new crates and lava tongues.

Currently, Mount Semeru is at level II or 'alert' status with the following recommendations.