Tectonic evolution of Savu
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.
The Sumba Ridge is no longer volcanically active,
however there are active volcanos on the island
of Flores, to the north. Sediments carried into
the Earth's crust heat up and rise in plumes of
magma, which cool and solidify to form igneous
rock.
The compression of the two tectonic plates is
causing the Savu Islands to rise at a rate of
about 1mm 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 (RS), struck 280km W/SW of Rai Jua. Since
1970, over 40 earthquakes greater than 6.0 RS
have struck within 500km of Savu. As can be seen
on the map, below, many
of these earthquakes were situated beneath the
sea, some shallow enough to cause tsunamis.
Earthquakes in East Nusa Tenggara
1970-2004
Enlarge
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Copyright © 2006 Ina
Tali/Francesca Von Reinhaart
© raijua.com
Resources:
The
Geology of Indonesia
IAGI (Ikatan Ahli Geologi Indonesia - Indonesian
Association of Geologists).
Fleury, Jean-Marc
De la Subduction Oceanique a la
Subduction Continentale Deformations Associees et
Heritage Structural: L'exemple du bloc
Sumba-Savu, terminaison orientale du fosse de la
Sonde.
These de Doctorat de l'Universite Pierre &
Marie Curie
Hamson, G. (2004)
The
Tectonic Evolution of the Banda Orogen, East
Timor.
Veritas Geophysical Services
Seismic data of the sea
bed surrounding Savu and Sumba.
Vorkink,
M.W. & Harris, R.A.
Geology, B.Y.U, provo, UT 84602
Geoscience in a
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