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How is Mount Merapi formed?

Answer:
Mount Merapi, located North of the city of Yogyakarta, on the island of Java, Indonesia was formed as the over 100 other active volcanoes on the Island as the Australian plate is subducted down under the Eurasian plate and the rock plate brings with it a lot of water molecules that then as they are lighter than the rock simmers up threw the mantle. When the magma comes close to the surface the pressure decreases and the magma expands very rapidly which can lead to very explosive eruptions.

In May 2006 there was a large earthquake close to Merapi and the volcano had an eruption at the same time. If the earthquake caused Merapi to erupt have been argued.
Contributor: C.Hainsaw
First answer by Jaaho. Last edit by Jaaho. Contributor trust: 32 [recommend contributor recommended]. Question popularity: 11 [recommend question].