Thursday 23 February 2012

Possible eruption on Tinakula.

Tinakula is a volcanic island in the Santa Cruz Islands, part of the Solomons, roughly 500 km east of San Cristobel, or 500 km north of Vanuatu. The island forms the peak of a massive stratovolcano (cone shaped volcano) rising 3-4 km from the sea floor to form an island 3.5 km across and 851 m high. The summit crater of Tinakula was breached by a landslide in 1965, forming an open scarp on the west side of the island that runs down to the sea.

Due to its remote location Tinakula is not visited very often, and so is not monitored from the ground. However it is visible to satellites, allowing a level of surveillance. On 13-14 February 2012 NASAs MODIS Instrument detected increased heat coming from Tinakula, and on 14 February the Earth Observing-1 satellite imaged a plume of ash and smoke issuing from the summit of the volcano.

Image of Tinakula captured by the Earth Observing-1 satellite on 14 February. Scale bar is 500 m. Earth Observatory.

Eruptions of this kind do not seem to be unusual on Tinakula. Satellites detected similar activity in 2004, 2006, 2007, 2009, 2010 and 2011. Eruptions were observed by boat in 1984 and 1985, and an eruption in 1971 was observed by airplane and seen from Trevanion Island, 20 km to the south; this eruption caused a small tsunami, though no-one was hurt. Numerous other explosions have been recorded on the island since its discovery by the Spanish in 1595. The island was inhabited till about 1840, when the entire population was wiped out in a particularly violent episode. Since then there have been sporadic attempts to colonize Tinakula by people from neighboring islands, but all have been abandoned.

The Santa Cruz Islands are a volcanic island arc on the boundary between the Pacific and Australian Plates. The Australian Plate is being subducted beneath the Pacific Plate. As it sinks into the Earth's interior it is heated, and partially melts. Some of the melted material rises through the overlying Pacific Plate as magma, forming the volcanoes of the Santa Cruiz Islands, including Tinkula.