Rajabasa
| Rajabasa | |
|---|---|
 | |
| Highest point | |
| Elevation | 1,281 m (4,203 ft)[1] |
| Listing | Ribu |
| Coordinates | 05°47′00″S 105°37′30″E / 5.78333°S 105.62500°E[1] |
| Geography | |
  Rajabasa Location within Sumatra  Rajabasa Location within Indonesia | |
 | |
| Location | South Lampung Regency, Lampung, Sumatra, Indonesia |
| Geology | |
| Rock age | Pleistocene |
| Stratovolcano | |
| Volcanic arc | Sunda Arc |
| Last eruption | Pleistocene[1] |
Rajabasa (Indonesian: Gunung Rajabasa) is an isolated 1,281-metre (4,203 ft) conical stratovolcano located along the Sunda Strait at the most southeastern point of Sumatra, Indonesia.[1] It is situated in South Lampung Regency, Lampung province, and is part of the Sunda Arc volcanic system.[1]
The volcano has a well-preserved summit crater measuring approximately 500 x 700 metres with a swampy floor, and is covered with dense vegetation.[1] The eroded edifice has a diameter of approximately 7.5 km, with the Balerang summit towards the southeast and the slightly higher Rajabasa cone to the northwest.[1]
Geography
[edit]Rajabasa is situated in South Lampung Regency, Lampung province, at the southeastern tip of Sumatra. The volcano lies approximately 50 km from the Krakatoa volcanic complex across the Sunda Strait.[2]
The eastern slopes of Mount Rajabasa are part of the Sekampung River basin.[3] All the watercourses originating from its upper reaches are utilized for agricultural irrigation on the downstream, southern side of the Sekampung River.[3]
The volcano is located in the districts of Kalianda and Penengahan, South Lampung Regency.[4] The Trans-Sumatran Highway (Jalinsum) runs along the northern side of the mountain, connecting Kalianda with the port of Bakauheni.[5]
Geology
[edit]Rajabasa is a stratovolcano of Pleistocene age, part of the Sunda Arc subduction zone system.[1] The volcano is composed of two main cones: Rajabasa to the northwest and Balerang to the southeast, which formed within a 25-km-diameter caldera at the southern tip of Sumatra.[1]
The volcanic history of Rajabasa is divided into several stages. According to Bronto et al. (2012), the volcanism began with the construction of the Pre-Rajabasa composite cone, followed by a destruction period that formed the Pre-Rajabasa Caldera.[6] The eruption points subsequently moved in a west-northwest to east-southeast direction, possibly controlled by a subsurface weak zone.[6]
Quaternary lavas at Rajabasa consist of andesite and basaltic andesite, along with breccias and tuff.[1] Hasibuan et al. (2020) reported that the youngest eruptive material, an andesite from the Rajabasa cone, was K-Ar dated at 0.120 ± 0.04 Ma (120,000 ± 40,000 years ago).[7]
Fumarolic activity
[edit]Fumarolic activity occurs on the foot and flanks of the volcano, indicating an active geothermal system beneath the edifice.[1] Increased fumarolic activity was reported in April 1863 and May 1892, though no eruptive activity followed.[1][2]
Eruptive history
[edit]The Global Volcanism Program has no record of Holocene eruptions from Rajabasa.[1] The volcano is considered to have last erupted during the Pleistocene, with the most recent dated material being approximately 120,000 years old.[1][7]
Although fumarolic activity has been observed and increased activity was reported in 1863 and 1892, it is not known when the volcano last erupted.[1][2] The volcano is currently classified as normal or dormant.[8]
Geothermal potential
[edit]Rajabasa is recognized as a significant geothermal energy prospect.[9] The volcano is associated with a geothermal system that has four identified reservoirs: Pangkul (south), Way Merak (south), Gunung Botak (south), and Kalianda (north).[10] Surface manifestations include thermal springs and fumaroles.[9]
Geothermal power plant
[edit]A geothermal power plant is currently under construction at Gunung Rajabasa.[11] The project consists of two units with a planned nameplate capacity of 110 MW each (total 220 MW).[11] The project is owned by a consortium including Sumitomo Corporation (33%), ENGIE SA (33%), and PT Supreme Energy (33%), with PT Supreme Energy Rajabasa (SERB) as the operator.[11] The project has confirmed a certain level of geothermal resource potential through surface surveys and geophysical exploration.[12]
Ecology
[edit]The volcano is covered with dense vegetation, with forest types including lowland and montane rainforest.[1] The mountain is home to various flora and fauna, including the endemic gecko species Cnemaspis rajabasa (cecak-batu rajabasa), which is named after the mountain.[13]
The slopes of Rajabasa are used for agricultural purposes, with smallholder farms and plantations cultivating crops such as rubber, coffee, and cocoa.[5]
Recreation and tourism
[edit]Mount Rajabasa is a popular destination for hikers and nature enthusiasts.[5] The mountain is nicknamed "kecil-kecil cabai rawit" (small but spicy) by locals, referring to its relatively low elevation but challenging terrain.[14]
The summit crater, with its swampy floor and surrounding forest, offers views of the Sunda Strait and the nearby coast.[5] The volcano is accessible from Kalianda and Bakauheni via the Trans-Sumatran Highway, making it a popular weekend destination for residents of Bandar Lampung.[5]
Visitors are advised to check current conditions with local authorities before climbing, as the volcano is active with fumarolic activity and geothermal manifestations.[8]
See also
[edit]
References
[edit]- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 "Rajabasa". Global Volcanism Program. Smithsonian Institution. Retrieved 2021-06-24.
- 1 2 3 "Rajabasa". Volcano World. Oregon State University. Retrieved 2026-08-07.
- 1 2 "Peta Interaktif". WebGIS MenLHK (in Indonesian). Retrieved 2023-10-09.
- ↑ "Gunung Rajabasa". Perpustakaan Badan Geologi (in Indonesian). Retrieved 2026-08-07.
- 1 2 3 4 5 "Gunung Rajabasa". Pariwisata Lampung Selatan (in Indonesian). Retrieved 2026-08-07.
- 1 2 Bronto, S.; Asmoro, P.; Hartono, G.; Sulistiyono (2012). "Evolution of Rajabasa Volcano in Kalianda Area and Its Vicinity, South Lampung Regency". Indonesian Journal of Geology. 7 (1): 11–25. doi:10.17014/ijog.7.1.11-25.
- 1 2 Hasibuan, R. F.; Ohba, T.; Abdurrachman, M.; Hoshide, T. (2020). "Temporal Variations of Petrological Characteristics of Tangkil and Rajabasa Volcanic Rocks, Indonesia". Indonesian Journal on Geoscience. 7 (2): 135–159. doi:10.17014/ijog.7.2.135-159.
- 1 2 "Rajabasa Volcano". Volcano Discovery. Retrieved 2026-08-07.
- 1 2 "Identification of Geothermal System Structure Based on Derivative Analysis and 3D Model of Gravity Satellite Data of Mount Rajabasa Area, South Lampung". IOP Conference Series. 2023. doi:10.1088/1755-1315/1233/1/012034.
- ↑ "Geothermal Reservoir Identification based on Gravity Data Analysis in Rajabasa Area". ITB. Retrieved 2026-08-07.
- 1 2 3 "Rajabasa geothermal power plant". Global Energy Monitor. Retrieved 2026-08-07.
- ↑ "Rajabasa Geothermal Power Project". INPEX Corporation. Retrieved 2026-08-07.
- ↑ "Cnemaspis rajabasa". The Reptile Database. Retrieved 2026-08-07.
- ↑ "Uji Fisik Mendaki Gunung Rajabasa Lewat Teropong Kota, Ini Tips Aman untuk Pendaki Pemula". Radar Lampung (in Indonesian). 2026-05-18. Retrieved 2026-08-07.
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