5 Facts about Mount Anak Krakatau

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  • Mount Anak Krakatoa. Tempo/Dian Triyuli Handoko

    Mount Anak Krakatoa. Tempo/Dian Triyuli Handoko

    TEMPO.CO, Bandarlampung - Mount Anak Krakatau located in Sunda Strait, South Lampung, erupted for 156 times since Tuesday, October 2 until early Wednesday. The eruption followed by incandescent lava and thunder sounds.

    Kristianto, an official at the Volcanology Center and Geological Disaster Mitigation (PVMBG), said Mount Anak Krakatau’s Observation Post recorded constant tremors which hampered the recording process of the mountain activity.

    The followings are five facts of Mount Anak Krakatau.

    1. Brief History

    Mount Anak Krakatau emerged from the sea on June 11, 1930, due to magmatic activity inside the caldera of Mount Krakatoa enormous eruption in 1883. In 2000, the volcanic mountain grew up to 300 meters above the sea level, and in October 2018, the height reached 338 meters.

    2. Warning Status

    The PVMBG issued the warning status (Alert Level 2) on Mount Anak Krakatau since 2012. “[Which means] the mountain activity may increase; it may erupt or not, or eruption may occur in the crater area,” said Devy Kamil Syahbana, the PVMBG official, in June 2018.

    Read: Mount Anak Krakatau Quake; Public to Steer Clear from Crater

    3. The color of column ash always changes

    A vulcanologist from Bandung Institute of Technology, Mirzam Abdurrachman, explained the color of the volcanic ash of Mount Anak Krakatau varies, for example in August, the dark column ash changed into light color.

    Meanwhile, based on observation conducted by PVMBG officers as noted in Magma Indonesia website, the column ash was in light color with thin intensity and as high as 50 meters from the mountain crater. In the night, the column ash showed firelights.

    Mirzam explained the color changes–called as ultravulcanian in vulcanology term– described the mountain process.

    4. Variety of lava colors

    The color of the lava flown from the mountain crater also diverse, such as red, yellowish red, yellow, and white. The bright orange lava means its temperature was at 1,000-1,050 degree Celsius, red at 800-1,000 degree Celsius, dark red at 650-800 degree Celsius, and brownish red at 500-650 degree Celsius.

    5. The mountain keeps growing

    The PVMBG official Wawan Irawan explained the eruption of Mount Anak Krakatau marked it was in a growing phase.

    According to Wawan, Mount Anak Krakatau grew by around 4 meters per year. “But, it does not erupt every year,” he said Monday, August 20. As of August 2018, the island diameter of Mount Krakatau reached 2 kilometers. The eruption that often occurs is strombolian eruptions which eject materials from the mountain (such as incandescent cinder, lapilli, and lava bombs).

    The material ejection due to Mount Anak Krakatau eruption was usually found outside the coastal border of the volcanic mountain island. Therefore, the safety zone set at 2 kilometers away from the mountain, from previously at 1 kilometer.