Selasa, 02 Oktober 2012
Senin, 01 Oktober 2012
Lake Toba
Lake Toba (Indonesian: Danau Toba) is a lake and supervolcano. The lake is 100 kilometres long
and 30 kilometres wide, and 505 metres (1,666 ft) at its deepest point.
Located in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about
900 metres (2,953 ft), the lake stretches from WikiMiniAtlas2°53′N 98°31′E / 2.88°N 98.52°E / 2.88; 98.52 to WikiMiniAtlas 2°21′N 99°06′E / 2.35°N 99.1°E / 2.35; 99.1. It is the largest lake in Indonesia and the
largest volcanic
lake in the
world.
Lake Toba is
the site of a supervolcanic eruption that occurred an estimated 69,000 to
77,000 years ago, a massive, climate-changing event. It is estimated to have
been a VEI 8 eruption.
It is the largest known explosive eruption anywhere on Earth in the last 25 million years. According to the Toba
catastrophe theory, it had
global consequences, killing most humans then alive and creating a population
bottleneck in Central
Eastern Africa and India that affected the genetic inheritance of all humans
today. However, this hypothesis is not widely accepted due to lack of evidence
for any other animal decline or extinction, even in environmentally sensitive
species. However, it has been accepted that the eruption of Toba led to a volcanic winter with a worldwide decline in
temperatures between 3 to 5 °C (5 to 9 °F), and up to 15 °C
(27.0 °F) in higher latitudes.
Geology
The Toba caldera complex in Northern Sumatra, Indonesia consists of four overlapping volcanic craters that adjoin the Sumatran "volcanic front". The youngest and fourth caldera is the world's largest Quaternary caldera (100 by 30 km (62 by 19 mi)) and intersects the three older calderas. An estimate of 2,800 km3 (670 cu mi) of dense-rock equivalent pyroclastic material, known the Youngest Toba tuff, was blasted from the youngest caldera during one of the largest single explosive volcanic eruptions in geologic history. Following the "Youngest Toba tuff eruption", a typical resurgent dome formed within the new caldera, joining two half-domes separated by a longitudinal graben.There are at least four cones, four stratovolcanoes and three craters visible in the lake. The Tandukbenua cone on the NW edge of the caldera is relatively lacking in vegetation, suggesting a young age of only several hundred years. Also, the Pusubukit volcano on the south edge of the caldera is solfatarically active.
Lake Toba (Indonesian: Danau Toba) is a lake and supervolcano. The lake is 100 kilometres long
and 30 kilometres wide, and 505 metres (1,666 ft) at its deepest point.
Located in the middle of the northern part of the Indonesian island of Sumatra with a surface elevation of about
900 metres (2,953 ft), the lake stretches from WikiMiniAtlas2°53′N 98°31′E / 2.88°N 98.52°E / 2.88; 98.52 to WikiMiniAtlas 2°21′N 99°06′E / 2.35°N 99.1°E / 2.35; 99.1. It is the largest lake in Indonesia and the
largest volcanic
lake in the
world.
Lake Toba is
the site of a supervolcanic eruption that occurred an estimated 69,000 to
77,000 years ago, a massive, climate-changing event. It is estimated to have
been a VEI 8 eruption.
It is the largest known explosive eruption anywhere on Earth in the last 25 million years. According to the Toba
catastrophe theory, it had
global consequences, killing most humans then alive and creating a population
bottleneck in Central
Eastern Africa and India that affected the genetic inheritance of all humans
today. However, this hypothesis is not widely accepted due to lack of evidence
for any other animal decline or extinction, even in environmentally sensitive
species. However, it has been accepted that the eruption of Toba led to a volcanic winter with a worldwide decline in
temperatures between 3 to 5 °C (5 to 9 °F), and up to 15 °C
(27.0 °F) in higher latitudes.
Geology
The Toba caldera complex in Northern Sumatra, Indonesia consists of four overlapping volcanic craters that adjoin the Sumatran "volcanic front". The youngest and fourth caldera is the world's largest Quaternary caldera (100 by 30 km (62 by 19 mi)) and intersects the three older calderas. An estimate of 2,800 km3 (670 cu mi) of dense-rock equivalent pyroclastic material, known the Youngest Toba tuff, was blasted from the youngest caldera during one of the largest single explosive volcanic eruptions in geologic history. Following the "Youngest Toba tuff eruption", a typical resurgent dome formed within the new caldera, joining two half-domes separated by a longitudinal graben.There are at least four cones, four stratovolcanoes and three craters visible in the lake. The Tandukbenua cone on the NW edge of the caldera is relatively lacking in vegetation, suggesting a young age of only several hundred years. Also, the Pusubukit volcano on the south edge of the caldera is solfatarically active.
. Bunaken
Bunaken is an island of 8 km², part of
the Bunaken
National Marine Park. Bunaken is
located at the northern tip of the island of Sulawesi, Indonesia. It belongs administratively to the
municipality of Manado. Scuba diving attracts many visitors to the
island.
Bunaken
National Park extends over an area of 890.65 km² of which only 3% is
terrestrial, including Bunaken Island, as well as the islands of Manado Tua, Mantehage, Nain and Siladen.
The waters
of Bunaken National Marine Park are up to 1,566 m deep in Manado Bay, with temperatures ranging between
27 to 29 °C. It has a high diversity of - corals, fish, echinoderms or sponges. Notably, 7 of the 8
species of giant clams that occur in the world, occur in Bunaken. It also
claims to have seven times more genera of coral than Hawaii,[1] and has more than 70% of all the
known fish species of the Indo-Western Pacific.[2]
Oceanic
currents may explain, in part, why Bunaken National Marine Park has such a high
level of biodiversity. Northeasternly currents generally sweep through the park
but abundant counter currents and gyros related to lunar cycles are believed to be a trap for free
swimming larvae. This is particularly true on the south side of the
crescent-shaped Bunaken Island, lying in the heart of the park. A snorkeler or diver in the vicinity of Lekuan
or Fukui may spot over 33 species of butterfly fish and numerous types
of groupers, damsels, wrasses and gobies. The gobies, smallish fish with bulging eyes and
modified fins that allow them to attach to hard surfaces, are the most diverse
but least known group of fish in the park.
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