All I know about Toba lake

The other tour place that well known in Sumatera is lake Toba ( prapat).
Thios is the lagest lake in north Sumatera, with good view, fresh atmosphere. In the middle of the lake, is a small island called Samosir. The place thar have the most visitor isa Tuk Tuk and Temok. Many tourist go there to buy hand made sourvenir.

Lake Toba (Indonesian: Danau Toba) is,100 km long and 30 km wide, in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about 900 m (3000 feet), stretching from 2.88° N 98.52° E to 2.35° N 99.1° E.

GEOLOGY
In 1949 the Dutch geologist Rein van Bemmelen reported that Lake Toba was surrounded by a layer of ignimbrite rocks, and that it was a large volcanic caldera. Later researchers found rhyolite ash similar to that in the ignimbrite around Toba (now called Young Toba Tuff to distinguish it from layers deposited in previous explosions) in Malaysia and India, 3000 km away. Oceanographers discovered Toba ash, with its characteristic chemical "fingerprint", on the floor of the eastern Indian Ocean and the Bay of Bengal.
HISTORY
The Toba eruption (the Toba event) occurred at what is now Lake Toba about 71,500 ± 4000 years ago. It had an estimated Volcanic Explosivity Index of 8 (described as "mega-colossal"), making it possibly the largest explosive volcanic eruption within the last twenty-five million years. Bill Rose and Craig Chesner of Michigan Technological University deduced that the total amount of erupted material was about 2800 cubic km (670 cubic miles) — around 2000 km³ of ignimbrite that flowed over the ground and around 800 km³ that fell as ash, with the wind blowing most of it to the west. By contrast, the 1980 eruption of Mount St. Helens ejected around 1.2 cubic km of material, whilst the largest volcanic eruption in historic times, at Mount Tambora in 1815, emitted the equivalent of around 100 cubic kilometres of dense rock and created the "Year Without a Summer" as far away as North America.

The Toba eruption was the latest of a series of at least three caldera-forming eruptions which have occurred at the volcano. Earlier calderas were formed around 700,000 and 840,000 years ago.[2]

To give an idea of its magnitude, consider that although the eruption took place in Indonesia, it deposited an ash layer approximately 15 cm (6 in) thick over the entire Indian subcontinent; at one site in central India, the Toba ash layer today is up to 6 m (20 feet) thick[3] and parts of Malaysia were covered with 9 m of ashfall.[4] In addition it has been calculated that 1010 metric tons of sulphuric acid was ejected into the atmosphere by the event, causing acid rain fallout.[5]


Landsat photo of Sumatra surrounding Lake TobaThe subsequent collapse formed a caldera that, after filling with water, created Lake Toba. The island in the center of the lake is formed by a resurgent dome.

Though the year can never be precisely determined, the season can: only the summer monsoon could have deposited Toba ashfall in the South China Sea, implying that the eruption took place sometime during the northern summer.[6] The eruption lasted perhaps two weeks, but the ensuing "volcanic winter" resulted in a decrease in average global temperatures by 3 to 3.5 degrees Celsius for several years. Greenland ice cores record a pulse of starkly reduced levels of organic carbon sequestration. Very few plants or animals in southeast Asia would have survived, and it is possible that the eruption caused a planet-wide die-off. There is some evidence, based on mitochondrial DNA, that the human race may have passed through a genetic bottleneck within this timeframe, reducing genetic diversity below what would be expected from the age of the species. According to the Toba catastrophe theory proposed by Stanley H. Ambrose of the University of Illinois at Urbana-Champaign in 1998, human populations may have been reduced to only a few tens of thousands of individuals by the Toba eruption.

ETHNIC
Most of the people who live around Lake Toba are ethnically Bataks. Traditional Batak houses are noted for their distinctive roofs (which curve upwards at each end, as a boat's hull does) and their colorful decor.

Lake Toba
Landsat photo
Location North Sumatra
Coordinates 2°37′N, 98°49′E
Lake type Volcanic/ tectonic
Primary outflows Asahan River
Basin countries Indonesia
Max length 100 km
Max width 30 km
Surface area 1130 km²
Max depth 505 m[1]
Water volume 240 km³
Surface elevation 905 m
Islands Samosir