Indonesia sits at the meeting point of the Indo-Australian, Eurasian and Pacific plates, forming part of the Pacific Ring of Fire. The Sunda subduction zone, where the Indo-Australian Plate dives beneath Southeast Asia, runs the length of the archipelago and makes Indonesia the country with the most active volcanoes on Earth and one of the highest rates of large earthquakes.
Its volcanic history includes the two most famous eruptions of the modern era: Tambora in 1815, whose ash triggered the global 'year without a summer', and Krakatoa in 1883, whose explosion was heard thousands of kilometres away. The 2004 Sumatra-Andaman earthquake, magnitude 9.1, generated a catastrophic tsunami that killed over 220,000 people around the Indian Ocean, while Merapi in Java remains one of the world's most dangerous active volcanoes.