Dutch geologist, Van Bemmelen (1949), called the Lake Batur in Kintamani, Bali, as one of the largest and most beautiful caldera in the world. With an area reaching 16.6 square kilometers, Lake Batur is the second largest caldera lake in Indonesia after Lake Toba in North Sumatra.
In addition to showing the beauty of the scenery, the extent of Lake Batur also illustrates the many volumes of material ejected during its formation.
Deadly eruption occurred about 29,300 years ago, beginning with vomit overlies 84 cubic kilometers (volcanic material). This massive eruption of Batur caldera formed first. Traces of volcanic material that was brought in the eruption spread to the north side of Ubud and Denpasar (about 40 miles from Lake Batur) with a thickness overlies up to 120 meters (Sutawijaya, 2000). For thousands of years, volcanic material was mined stone and is now the community into building materials.
The second major eruption occurred 20,150 years ago, spewing 19 km3 overlies and form a second caldera. At the base of the second caldera is then grown Batur Volcano.
Traces of this second major eruption in the complex revealed perfect Pura Gunung Kawi (approximately 21 miles from Lake Batur). Ignimbrite that forms cliffs up to 20 meters was carved into the complex to honor ancestral spirits, including the King Udayana. This temple was built around the 11th century.
Indyo Pratomo, a geologist at the Geological Museum of Bandung, describe the awesomeness that second caldera eruption through volcanic material outcrops in the cliffs around Besakih-Panelokan Road, 10 kilometers from the caldera of Batur. Outcrops that show a series of eruptions before the massive eruption which throws the contents of the magma chamber to the air up to 40 km.
Phase evolution
Dutch geologist, GLL Kemmerling (1917), concluded that the evolution of Mount Batur occur in five stages.
First, the volcanic activity that formed the old cone of Mount Batur to altitude of 3,000 meters above sea level. The second stage is a massive eruption that causes volcanic cones disappear by half.
This huge eruption that produced the first and remains the basis of the caldera caldera on the northwest side of railroad known as Kintamani. These steps are about 300 meters above the caldera second base.
The third stage is the formation of Mount Abang and other small volcano. Batur Volcano rebuilding followed the fourth stage, namely the destruction of volcanic cones. This second major eruption causing amblesnya first base and the loss of half of the caldera of Mount Abang body.
Van Bemmelen rate, the eruption was followed by the formation of Lake Batur crescent-shaped. This lake has the longest point of 13.8 km and 10 km with the shortest point of the high embankment of up to 2152 meters 1267 meters. Trunyan community, known as the Bali Mula, inhabiting the banks of the east side of this lake for hundreds of years. In fact, many findings megalithic cult around Batur indicate that this area has been inhabited since prehistoric times.
The fifth stage of evolution is the formation of the cone of Mount Batur volcano that began about 5,000 years ago and continued until today. However, the eruption of Batur Volcano young new existence since 1804 and has happened 28 times until 2000.
Wheller and Varne, researchers at the Department of Geology, University of Tasmania, Australia (1986), concluded, catastrophic eruption of Batur can be repeated. The conclusion was made after examining both the process of formation of basaltic magma of Mount Batur (dilute) to dasitik (very thick).
Magma dasitik, according to The Center for Volcanology and Geological Hazard Mitigation Surono, very thick and rich gas causing tremendous eruption, as happened at Mount Krakatoa erupted during 1883.
Wheller and Varne also found a similarity of chemical properties of rocks and minerals between Batur and Krakatoa. Although magma spewed Batur in 28 times the last eruption are basaltic, according Wheller and Varne, the nature of this magma could turn into dasitik.
Threat to the future
At the foot of the young volcanoes scattered settlements which follows the shoreline of Lake Batur. Since hundreds of years ago, people Trunyan has occupied the east side of the lake. In fact, human life around the lake is estimated to have occurred since prehistoric times, marked by numerous findings of worship characterized by megalithic stones.
Eruption occurred many times, leleran lava hit the settlements, ash and pyroclastic flows (hot clouds) did not make clear the basis of residents around the caldera.
Volcano Batur volcanic activity recorded from 1804 to 2000 was not such a paroxysmal eruption occurred at Mount Agung in 1963. Pyroclastic material being thrown into the air are concentrated in the caldera.
Dilute cause bursts of lava fountains that resemble a burning at night. Beautiful, but deadly. The beauty of the current eruption of Batur disguise traces of the deadly eruption and form part faces the island of Bali.
The evolution of Batur Volcano continues to run behind the panoramic beauty of the caldera. Nature works follow the arguments can only be guessed humans. The silence and the look of natural scenic always keep the risk in the country who wrapped the ring of fire.
(Indira Permanasari / Augustine Handoko / Ahmad Arif)
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