Toba Lake - Prapat

Lake Toba North Sumatra Indonesia

Lake Toba also known as Danau Toba in Indonesia is the largest volcanic lake ( crater lake ) in the world. At 100 km long and 30 km wide, measuring 505 m at its deepest point, it is situated in the middle of the northern part of the Indonesian island of Sumatra.Surrounded by tall mountains, it cradles the large island of Samosir in its middle.

Uniqueness of Lake Toba:

Unlike any other lake, if you think about the location — close to the equator — and look at the picture, you will realize that there is something strange about the lake. Most large lakes were formed by glaciers; large lakes close to the equator are sometimes formed by the damming of a large river. But there is no large river flowing into Lake Toba. The lake has a different and more dramatic origin.

Lake Toba marks the site of the largest volcanic eruption in the last 2 million years. It is, like Yellowstone, a “resurgent caldera”, or as geologists David Alt and Daniel Hyndman call this type of volcano, a “perfect horror”. Alt and Hyndman call resurgent calderas “perfect horrors” because they are both violent and enormous.

The size of Lake Toba may be a little difficult to grasp from the picture, so to give you some comparisons.

In Washington state, if the lake were aligned north to south in the Puget Sound area, it would stretch from Everett to Tacoma. In the Chicago area, it would stretch from Waukegan to Gary. In New York, it would stretch from West Point to the Statue of Liberty. This is one enormous volcano.

And its most recent eruption, about 75,000 years ago, was in Volcanic Explosivity Index of 8The Young Toba Tuff has an estimated volume of 2,800 cubic kilometers (km) and was erupted about 74,000 years ago. The Huckleberry Ridge Tuff, erupted at Yellowstone 2.2 million years ago, has a volume of 2,500 cubic km. The Lava Creek Tuff, erupted at Yellowstone 600,000 years ago, has a volume of 1,000 cubic km. The May 1980 eruption of Mount St. Helens produced 1 cubic km of ash. Not shown in the diagram, is the Fish Canyon Tuff of the San Juan Mountains of Colorado. The Fish Canyon Tuff was erupted 27.8 million years ago and has an estimated volume of 3,000 cubic km.

The volume of the youngest eruption is estimated at 2,800 cubic km, making the eruption the largest in the Quaternary. Pyroclastic flows covered an area of at least 20,000 square km. Up to 1200 feet (400 m) of Young Toba Tuff is exposed in the walls of the caldera. On Samosir Island the tuff is more than 1800 feet (600 m) thick. Ash fall from the eruption covers an area of at least 4 million square km (about half the size on the continental United States).

That eruption would not have been pleasant for our ancestors. In fact, some scientists believe that the eruption, and the volcanic winter that followed, almost wiped out homo sapiens, cutting our population down to as few as 3,000, or even as few as 1,000. (That population bottleneck, as geneticists call it, would explain why humans vary less genetically that one would expect from the age of our species.)

How to Get to Lake Toba:

Since it is located in North Sumatra, the only way there is through the city of Medan - North Sumatra Indonesia

Lake Toba is about 4 hours drive by car from Medan City. You can travel by public bus which may take longer to about 6 hours. The usual stop is the town of ” Pematang Siantar ” halfway to Lake Toba for a toilet break.

Local town is known as Prapat / Parapat

Local transportation around the lake takes the form of boats. You can also hire a motorcycle for a day or two and get out and about ( Rp.50,0000 per day inclusive of 4 litres of petrol ). There are no police checking licenses and there is not much traffic - just watch out for the big trucks, buses and diabolical bridge.