Sunda Arch
The Sunda Arc is a 6000 km long island arc formed by the subduction of the Indo-Australian lithospheric plate beneath the Sunda and Burma plates arises. It includes, for example, the Andaman and Nicobar Islands , the large islands of Sumatra and Java , the Lesser Sunda Islands , but also the volcanic island of Krakatau , which exploded in the Sunda Strait in 1883 .
The Sunda arch on the Sunda and Burma plates is completed by the Sunda trench where the Australian plate dips. Then there is an approximately 700 km wide Fore-arc Basin and a Back-arc Basin , the Andaman Basin. There, the Burma and Sunda plates have been driven apart in several rift zones for about four million years by the so-called ocean floor spreading. The Andaman Sea in the Andaman Basin, which is around 650 kilometers wide today, has existed since the Oligocene . Another back-arc basin exists in the Lesser Sunda Islands, the Banda Basin, which the north-south about 600 kilometers Banda was born. The eastern part of the Sunda Arc is estimated to be over 100 million years old, while the northwestern part is only around 40 million years old.
Seaquake in the Indian Ocean
The 2004 Sumatran-Andaman quake in the Indian Ocean had its epicenter off the northwest coast of Sumatra, followed by aftershocks in the Andaman and Nicobar Islands, including the 2005 Sumatra earthquake . In addition to the loss of around 228,000 human lives, the seaquake also shifted the Nicobar Islands and the Simeulue Island off the north-west coast of Sumatra by around 15 meters in a south-westerly direction.
As a reaction to the seaquake, the German Indonesian Tsunami Early Warning System (GITEWS) was founded in order to be able to recognize a possible tsunami danger early in the future. Trial operations began in 2008 and the system was handed over in Jakarta in 2011.
On July 17, 2006, a tidal wave that caused the earthquake off Java left several hundred dead. According to the Pacific Tsunami Warning Center , the quake had a magnitude of 7.7. The tidal wave is said to have been at least two meters high.
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- ↑ KA Kamesh Raju: Three-phase tectonic evolution of the Andaman back arc basin. Current Science, Vol. 89, No. 11, 10 December 2005. ( PDF file )