ORIGINS OF LAKE TOBA
Now a complex of Mount Toba Lake Toba caldera is the island of Samosir in the middle.
Mount Toba is the giant volcano that is active volcano in the category of very large, estimated last erupted about 74,000 years ago leaving a lake that is Lake Toba, North Sumatra, Indonesia as the largest caldera in the world.
The scientific evidence
In 1939, the Dutch geologist Van Bemmelen report, Lake Toba, a length of 100 kilometers and 30 kilometers wide, surrounded by relics of pumice from the eruption. Therefore, Van Bemmelen concluded, Toba is a volcano. Later, other researchers discovered dust rhyolite (rhyolite) rocks are the same age as Toba in Malaysia, even as far as 3,000 kilometers to the north to central India.
Some oceanographers also reported finding traces of Toba rocks in the Indian Ocean and Bay of Bengal. The researchers start, Van Bemmelen also Aldiss and Ghazali (1984) has been created through a suspected Toba eruption mahadahsyat. However, other researchers, Vestappen (1961), Yokoyama and Beatles (1981), and Nishimura (1984), assumed the caldera was created through several eruptions. Researchers later, Knight and colleagues (1986) and Chesner and Rose (1991), provides an estimate of the details: Toba caldera created by three giant eruptions.
Research about Toba is not over until now. So, still a lot of mystery behind the sleeping giant. One of the newest generation of researchers Toba was governor of Indonesia, seismologists at the Meteorology and Geophysics Agency. Undergraduate physics from the University of Indonesia's 1985 graduates earned a doctorate from Renssealer Polytechnic Institute, New York, in 1998, for his studies of the Toba.
Being in three tectonic plates
Location of Mt Toba (now: Lake Toba), in Indonesia is prone to disasters. This is related to the position of Indonesia which is located at the confluence of three tectonic plates, the Eurasian, Indo-Australian Plate and the Pacific. A total of 80% of the territory of Indonesia, located on the Eurasian plate, which includes Sumatra, Java, Kalimantan, Sulawesi and Banda.
This continental shelf life, every year they shifted more or mashing plate with a certain distance. Eurasian Plate which is a continental plate is always a target. Indo-Australian Plate as far as mashing the Eurasian plate 7 cm per year. Or a shift of the Pacific Plate relative to the Eurasian plate as far as 11 cm per year. Of that shift came the mountain range, including the Toba volcano.
If there is a collision, ocean plates containing sediment layers beneath the continental shelf infiltrate. This process is then called subduction or infiltration.
Mount the result of subduction, one of Mount Toba. Although it is no longer shaped mountain, the remains kedasahyatan eruption still appears today. Lake Toba is a caldera formed by the eruption of Mount Toba about three times the first 840 million years ago and the last 74,000 years ago. The part that was thrown from the eruption reached an area of 100 km x 30 km square. The remaining regions then form the caldera. In the middle then comes Samosir Island.
Eruption
Formerly Mount Toba erupted three times.
• The first eruption occurred around 840 million years ago. This eruption produced the caldera in the south of Lake Toba, covering area and Porsea Prapat.
• The second eruption which has a smaller force, occurred 500 million years ago. The eruption formed a caldera in the north of Lake Toba. Precisely in the area between the Haranggaol Silalahi. Of the two eruptions, the eruption ketigalah most powerful.
• The third eruption 74,000 years ago produced the caldera, and became Lake Toba to Samosir Island now in the middle.
Mount Toba supervolcano is classified. This is because Mount Toba has large pockets of magma that erupted when a huge caldera. Caldera volcano hundreds of meters, whereas it Supervolacano tens of kilometers.
Of particular interest is the gravity anomaly at Toba. According to the law of gravity, from one place to another will have the same gravity when it has mass, and relativity of the same height. If there are other materials that are there with different masses, the attractiveness of different styles. Imagine the mountain erupted. A lot of the material that comes out, it means loss of mass and force reduced its appeal. Then going up-lifting (removal). This is what led to the emergence of Samosir Island.
Magma below continued upward, slowly. He does not have the power to erupt. This movement is trying to adjust to normal gravity. It happens over a period of thousands of years. Only Samosir is lifted because it was the weakest area. While other areas are caldera wall.
Now a complex of Mount Toba Lake Toba caldera is the island of Samosir in the middle.
Mount Toba is the giant volcano that is active volcano in the category of very large, estimated last erupted about 74,000 years ago leaving a lake that is Lake Toba, North Sumatra, Indonesia as the largest caldera in the world.
The scientific evidence
In 1939, the Dutch geologist Van Bemmelen report, Lake Toba, a length of 100 kilometers and 30 kilometers wide, surrounded by relics of pumice from the eruption. Therefore, Van Bemmelen concluded, Toba is a volcano. Later, other researchers discovered dust rhyolite (rhyolite) rocks are the same age as Toba in Malaysia, even as far as 3,000 kilometers to the north to central India.
Some oceanographers also reported finding traces of Toba rocks in the Indian Ocean and Bay of Bengal. The researchers start, Van Bemmelen also Aldiss and Ghazali (1984) has been created through a suspected Toba eruption mahadahsyat. However, other researchers, Vestappen (1961), Yokoyama and Beatles (1981), and Nishimura (1984), assumed the caldera was created through several eruptions. Researchers later, Knight and colleagues (1986) and Chesner and Rose (1991), provides an estimate of the details: Toba caldera created by three giant eruptions.
Research about Toba is not over until now. So, still a lot of mystery behind the sleeping giant. One of the newest generation of researchers Toba was governor of Indonesia, seismologists at the Meteorology and Geophysics Agency. Undergraduate physics from the University of Indonesia's 1985 graduates earned a doctorate from Renssealer Polytechnic Institute, New York, in 1998, for his studies of the Toba.
Being in three tectonic plates
Location of Mt Toba (now: Lake Toba), in Indonesia is prone to disasters. This is related to the position of Indonesia which is located at the confluence of three tectonic plates, the Eurasian, Indo-Australian Plate and the Pacific. A total of 80% of the territory of Indonesia, located on the Eurasian plate, which includes Sumatra, Java, Kalimantan, Sulawesi and Banda.
This continental shelf life, every year they shifted more or mashing plate with a certain distance. Eurasian Plate which is a continental plate is always a target. Indo-Australian Plate as far as mashing the Eurasian plate 7 cm per year. Or a shift of the Pacific Plate relative to the Eurasian plate as far as 11 cm per year. Of that shift came the mountain range, including the Toba volcano.
If there is a collision, ocean plates containing sediment layers beneath the continental shelf infiltrate. This process is then called subduction or infiltration.
Mount the result of subduction, one of Mount Toba. Although it is no longer shaped mountain, the remains kedasahyatan eruption still appears today. Lake Toba is a caldera formed by the eruption of Mount Toba about three times the first 840 million years ago and the last 74,000 years ago. The part that was thrown from the eruption reached an area of 100 km x 30 km square. The remaining regions then form the caldera. In the middle then comes Samosir Island.
Eruption
Formerly Mount Toba erupted three times.
• The first eruption occurred around 840 million years ago. This eruption produced the caldera in the south of Lake Toba, covering area and Porsea Prapat.
• The second eruption which has a smaller force, occurred 500 million years ago. The eruption formed a caldera in the north of Lake Toba. Precisely in the area between the Haranggaol Silalahi. Of the two eruptions, the eruption ketigalah most powerful.
• The third eruption 74,000 years ago produced the caldera, and became Lake Toba to Samosir Island now in the middle.
Mount Toba supervolcano is classified. This is because Mount Toba has large pockets of magma that erupted when a huge caldera. Caldera volcano hundreds of meters, whereas it Supervolacano tens of kilometers.
Of particular interest is the gravity anomaly at Toba. According to the law of gravity, from one place to another will have the same gravity when it has mass, and relativity of the same height. If there are other materials that are there with different masses, the attractiveness of different styles. Imagine the mountain erupted. A lot of the material that comes out, it means loss of mass and force reduced its appeal. Then going up-lifting (removal). This is what led to the emergence of Samosir Island.
Magma below continued upward, slowly. He does not have the power to erupt. This movement is trying to adjust to normal gravity. It happens over a period of thousands of years. Only Samosir is lifted because it was the weakest area. While other areas are caldera wall.
