Origins of Lake Toba

North Sumatra - In 1930, Reinout Willem van Bemmelen, a leading Dutch East Indies geologist, transfixed watching the rocks in a hill not far from Toba Lake. He uses a small hoe to dig and determine the thickness of rocks in multiple locations.
Van Bemmelen down the area around Toba Lake, or to an area farther than he researched previously, to determine the thickness of the rocks. All that he did for years with the guidance of scientific instincts.
Overlies rocks is ignimbrit, a mixture of hardened volcanic ash (tuff) and pumice grains are rich in silicate - acidic rocks. Ignimbrit volcanic eruptions occur when a large-scale plunked massive hot clouds.
Van Bemmelenn find ignimbrit around Lake Toba so thick, but thinner at an area away from the lake. He also found abundant tuff during the study between 1930-1939.
The findings led Van Bemmelen to the development of super volcano theory. According to him, Toba Lake, the basin area of ​​2,270 square kilometers with a length of 100 kilometers and a width of 30 kilometers, is the volcanic lake.
In Geology of Indonesia, Van Bemmelen said that Toba Lake was formed after the eruption of a super volcano. He also popularized the term Tumor Batak, or a very large dune that separates the lake Toba with Bukit Barisan Mountains.
Tumor Batak is a volcano that sustains Toba Lake. Van Bemmelen also mentioned Tumor Batak as Mount Toba, which stands on a large fault system Sumatra.
Research in the following years supervolcano clarify the theory right on Toba Lake current position. Van Bemmelen and Stauffer also found rhyolite in Malaysia. William and Royce reported rhyolite in India are as old as the discovery of the Van Bemmelen and Ninkovich.
Findings rhyolite in locations far from Toba Lake led experts to estimate the strength of the eruption 74 thousand years ago. The results were surprising, Toba Lake was formed from volcanic eruptions giant, with a very large magma chamber beneath Toba Lake.
Other geologists estimate super volcano that created Toba Lake powered 300 times larger than the eruption of Mount Tambora in 1815, and was recorded as the largest eruption in the history of the earth.
Source: Koran Tempo, Monday September 26th 2016, page 7th

Lake Toba in Map. Source: Asianreisender

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