In geography, we learn about water system in the land and the sea. Particularly for water system in the land, there are three ecosystems of river, swamp, and lake. Lake is all about basin that is filled with water. Based on its water type, lakes are divided into salt and freshwater lakes. There are some differences between sea water and mountain water.
While according to their mode of formation, lakes are divided into several types:
- Tectonic lake
- Volcanic lake
- Mixed lake (tectonicand volcanic)
- Glacial lake
- Oxbow lake (formed after the meander river cuts the its neck)
- Karst lake (formed within karst region)
In Indonesia, several types of lakes exist, such as volcanic lake, tectonic lake, fluvial lake, and oxbow lake. This article is going to elaborate 8 examples of volcanic lakes in Indonesia. Meanwhile, there are some popular lakes in Papua that you need to know. Volcanic lake is formed due to the collapsed caldera and explosive eruption which can move material in such large quantity. Volcanism itself is caused by regional tectonic activity like subduction and rifting.
According to the deformation process, volcanic lake is divided into three steps:
- The caldera is collapsing because of big eruption, then the caldera shows some ring fractures and becomes the next deposition center;
- Subaerial sediments, erosion, and debris fans are accumulated in the base and edge of caldera;
- The sediment filling occurs when the eruption and volcanism are still active, producing higher rate of sedimentation. During this process, caldera wall will get eroded. Therefore the lake becomes larger, while its edge is shallow. After the eruption ends, turbidite sediment dominantly occurs.
Generally, volcanic lake or caldera consists of:
- Crater rim, crater wall as the lake cover
- Crater sediments, sediment deposit from the rocks as the lake base
According to previous explanation, there are some examples of volcanic lakes throughout Indonesia provinces, some of them are:
- Maninjau Lake, located in West Sumatra Province, astronomically in 0˚12’26,62’’S– 0˚25’02,80’’S and 100˚E7’43,74’’ – 100˚E16’22,48’’ in Tanjung Raya, Agam District. The lake is located on 461.5 meter above sea level. Maninjau Lake has an area of 97.375.000 m2, with the longest length of 16.469 meter, and the maximum wide of 7.500 meter. The water volume is around 10.226.001.629 m3, with the average depth of 105 meter and area of 13.260 hectare. In spite of those numbers, Maninjau Lake is not one of those 10 largest lakes in the world.
- Tondano Lake, located in Tondano, North Sulawesi Province, between Lambean, Kaweng, and Masarang Mountains. Tondano lake is one of 8 examples of volcanic lakes in Indonesia.
- Tujuh (seven) Mountain Lake, located in Kerinci District, Jambi Province, Sumatera. Astronomically, the lake is located in 1˚42’23’’Ndan 101˚E24’42’’ in the area of Tujuh Mountain. The lake got its name from the seven mountains that surround the lake, there are Hulu Tebo Mountain, Hulu Sangir Mountain, Madura Besi Mountain, Lumut Mountain, Selasih Mountain, Jar Panggang Mountain, and Tujuh Mountain itself.
- Segara Anakan Lake, located in the Rinjani Mountain.
- Kelimutu Lake, located in East Nusa Tenggara and it is popular as the three colored lake. Not only Kelimutu in Indonesia, Vietnam also has some interesting lakes.
- Telaga Lake, located in Dieng Mountain, in Central Java Province.
- Toba Lake, located in Samosir District, North Sumatera Province, and the largest volcanic lake in Indonesia. Toba Lake is located on 905 meter above sea level, it has the length of 275 km, the wide of 150 km, and an area of 1.130 km2. The lake was created due to volcanism activity around 73.000 – 75.000 years ago.
- Tolire Lake, located in Gamalama Mountain in Ternate Island. Astronomically, the lake is located in 127,29˚E– 127,39˚E dan 0,75˚N – 0,87˚ The lake has relatively short diameter of 11 km and area of 76km2.
From 8 examples of volcanic lakes in Indonesia above, it can be explained that volcanic lake is naturally formed due to volcanic explosion, then it creates large basin consists of earth materials like sulfur and geothermal. Besides, volcanic lake has geothermal resources with various depths.
Comparing to tectonic lake, volcanic lake is quite shallower and the water quality is highly impacted by its volcano activity. There are some properties of water in life though. When the volcano erupts, the water contains high rate of sulfur with its typical strong scent. Volcanic lake should attract local and foreign tourists to enjoy natural scenery from volcano eruption.