Indonesia is an immense archipelago of more than 17,000 islands extending over 5000 km from east to west between 95 and 141 degrees E, and crossing the equator from 6 N to 11 S. It is situated at the boundaries of three major plates: Eurasia, India-Australia, and Pacific-Phillipine Sea.
Situated on a major fault and part of the infamous volcanic zone called the "Ring of Fire", Indonesia was created from violent seismic activity that created most of the 17,000 islands that form the nation today. The islands of Indonesia have a great effect on the change of the Australian and Pacific tectonic plates. The Australian plate changes slowly with an upward movement into the small plates of the Pacific plate that moves southward. Between these lines, the islands of Indonesia stretch out.
This makes Indonesia one of the most changing geological areas in the world. There are 400 volcanic mountains on the islands of Indonesia of which 100 are active.
The eruption of super volcano Toba (Nth Sumatra) some 74,000 years ago caused the worlds largest known explosion in 2 million years and formed a lake 100 km long and 30 km wide with an island in the middle the size of Singapore. Many scientists believe this eruption and its long-term impact on the earth altered the genetic make-up of the human species.
From the 1815 eruption of Mt Tambora to the 1883 explosion of Krakatau, Indonesia's seismic tragedies of the past two centuries have altered human history well beyond the Pacific's so-called Ring of Fire, sending geopolitical and economic repercussions across the planet.
The 1815 eruption of Mt. Tambora had far reaching effects. It killed 100,000 people on Sumbawa Island and as volcanic ash settled over the globe the Northern Hemisphere would come to know 1816 as "the year without a summer".
the 1883 eruption of Krakatau off southern Sumatra is considered by some historians to be the worlds first global media event. The invention of the telegraph and creation of news services like Reuters allowed many to "read of the devestation over breakfast the next day". Tsunamis generated by that eruption killed 40,000 on Java and Sumatra. The explosion was heard as far away as Australia and India and threw millions of tons of ash into the atmosphere that would cool temperatures around the world for many years.
Since 2000, earthquakes, volcanic eruptions and tsunamis have continued to disrupt life in Indonesia, causing the deaths of over 250,000 people and the destruction of 2,000,000 homes and buildings.