Savu - Vulcanism

Vulcanism

The Savu Islands are situated in a tectonic subduction zone, where the Indo-Australian Plate is moving northward, sliding under the Eurasian Plate. The islands lie on a ridge that was created by volcanic eruptions caused by the plate movement. Sediments carried into the Earth's crust heat up and rise in plumes of magma, which cool and solidify to form igneous rock. The Sumba Ridge is no longer volcanically active, however there are active volcanoes on the island of Flores, to the north.

The compression of the two tectonic plates is causing the Savu Islands to rise at a rate of about 1 mm per year. Occasionally, however, the tectonic plate suddenly slips a much greater distance, resulting in an earthquake. In 1977, a major earthquake, registering 7.9 on the Richter Scale, struck 280 km W/SW of Raijua. This triggered an enormous tsunami, which swept across the coastal plain at Seba, reaching as high as the airport. No one was reported missing on Savu or Rai Jua. However, on the neighbouring islands of Sumba and Sumbawa, the death toll reached 180.

• Interactive map showing major earthquakes in East Nusa Tenggara between 1970 and 2005 (requires Flash Player).