Mount Merapi, a volcano in central Java considered to be one of Indonesia's most active, erupted slightly after 5.15 am local time on Thursday 13 February 2020, acording to the Badan Nasional Penanggulangan Bencana, producing an ash column about 2 km in height. This is the first significant eruption on the volcano since November 2019, and led to ash falls within 1 km of the volcano in all directions, and as far as 10 km away to the south, the direction of the predominant winds at the time of the eruption.
An ash column over Mount Merapi, Java, on 13 February 2019. AFP.
Mount Merapi lies in a densely populated area of Java, on the borders of Central Java and Yogyakarta Provinces, only 28 km to the north of Yogyakarta city. It has been erupting more-or-less continuously since 1548, and has been responsible for numerous fatalities, most recently in 1994 when a pyroclastic flow (avalanche of hot gas and ash) killed 27 people, mostly in the town of Muntilan, to the west of the volcano. Since then Merapi has undergone tow major eruptive episodes, in 2006 and 2010, without any further loss of life, largely due to prompt evacuations by Indonesian authorities.
The approximate location of Mount Merapi. Google Maps.
The Indo-Australian Plate, which underlies the Indian Ocean to the south of Java, is being subducted beneath the Sunda Plate, a breakaway part of the Eurasian Plate which underlies Java and neighbouring Sumatra, along the Sunda Trench, passing under Java, where friction between the two plates can cause Earthquakes. As the Indo-Australian Plate sinks further into the Earth it is partially melted and some of the melted material rises through the overlying Sunda Plate as magma, fuelling the volcanoes of Java and Sumatra.
Subduction along the Sunda Trench. Earth Observatory of Singapore.
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