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Supervolcano Lake Toba
This cache is dedicated to the supervolcano & the largest volcanic lake in the world, Lake Toba in the North of Sumatra,
Indonesia. It's one of the most stunning paradises on earth you could ever visit. Bigger than Singapore the Danau Toba is 100 kilometres long & 30 kilometres wide and has an island in the center. It was formed by a gigantic volcanic eruption 70.000-75.000 years ago. The eruption had a VEI intensity of 8 and is the largest known eruption in the last 25 million years, which caused a massive climate-changing event. The Toba catastrophe theory says that these global consequences killed most humans than alive and created a population bottleneck that affected the genetic inheritance of all humans today.
Supervolcanoes produce eruptions with ejecta greater than 1.000 cubic kilometers. They can occur when magma in the Earth rises into the crust from a hotspot but is unable to break through the crust. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure. Super volcanic eruptions cover huge areas with lava & volcanic ash and cause a long-lasting change to weather that can threaten the extinction of species.
There are six known supervolcanos:
. Yellowstone (US)
. Long Valley (US)
. Valles Caldera (US)
. Taupo Volcano (New Zealand)
. Aira Caldera (Japan)
. Lake Toba (Indonesia)
The Toba eruption was the latest of a series of at least three caldera-forming eruptions which have occurred at the volcano, with earlier calderas having formed around 700.000 and 840.000 years ago. The total amount of erupted material was about 2.800 cubic kilometers (2.000 cubic kilometers flowed over the ground, 800 cubic kilometers fell as ash) causing a 15 centimeters thick ash layer over the entire South Asia. 10.000 million metric tons of sulfuric acid was ejected into the atmosphere by the Toba event, which created acid rain fallout. Compared to the latest Yellowstone eruption of Lava Creek 630.000 years ago the Toba eruption was about three times that size. It lasted two weeks, but the volcanic winter resulted in a decrease in average global temperatures by 3 to 3.5 degrees Celsius for several years. This resulted in a planet-wide die-off.
 
The subsequent collapse formed a caldera that, after filling with water, created Lake Toba. The pressure from the dormant magma, which has not yet erupted, caused Samosir Island to emerge in the center of the lake. It's the largest island (627 km²) within an island and was originally connected to the surrounding caldera wall by a small isthmus, which was cut through to aid navigation. The small town Parapat (N02° 39.467, E 098° 56.350) on the edge of Lake Toba is the primary transit point to the island by ferry. You can travel by land to Parapat, which is about 4 hours by car from Medan. There are also regular buses from most of the big cities in Sumatra. The main bus terminal is on Jl Sisingamangaraja around 1 km from the centre of town. If you really want to enjoy the magical atmosphere of Lake Toba then take one of the ferries (Port Tigaraja for passengers or Aji Batato for car transportation) visit the island. On Lake Toba you will have stunning insights in a different world. The green mountain range & two silent volcanos will tower up next to you. You won't see an end. Everything is blue. The water will merge with the sky and sometimes there'll be a mystical patchy fog on the lake creating an even more surreal setting.
 
to log the cache
... go to Parapat (N02° 39.467, E 098° 56.350) e.g., where you can see the lake glittering in all of its beauty.
... post a picture of you and/or your GPS at Lake Toba and
... send us the answers to the following questions:
(DO NOT put them in your log!)
1. At what altitude are you?
2. What are the two possibilities to get to Samosir Island?
3. What is the volcano number of Toba?
Enjoy this unforgettable trip!
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