Geology of Indonesia active volcanoes formed Sumatra, Java, Bali, and Nusa Tenggara islands, most of which, particularly Java and Bali, emerged within the last 2–3 million years. The Pacific and Australian plate movements controlled the tectonics of the eastern portion of Indonesia. The tectonics processes in Indonesia formed major structures in Indonesia. The most prominent fault in the west of Indonesia is the Semangko Fault or the Great Sumatran Fault, a dextral strike-slip fault along Sumatra Island (about 1900 km). The formation of this fault zone is related to the subduction zone in the west of Sumatra. Palu-Koro fault is another major structural
Demographics of Indonesia Indonesia is the world's most populous Muslim-majority nation; almost 87.18% of Indonesians declared themselves Muslim in the 2010 census. 9.87% of the population adhered to Christianity (of which more than 70% were Protestant), 1.69% were Hindu, 0.72% Buddhist, and 0.56 of other faiths. Most Indonesian Hindus are Balinese and most Buddhists in modern-day Indonesia are Tionghoa. Indonesian is the official language but there are many different languages native to Indonesia. According to Ethnologue, there are currently 737 living languages spoken in Indonesia, the most widely spoken being Javanese. A number of Chinese varieties, most prominently Min Nan, are also spoken.