A magnitude 8 earthquake has hit near the Solomon Islands in the Pacific Ocean, causing a tsunami that and may have destroyed a number of villages. Tsunami warnings were issued as far afield as Australia, but were soon cancelled.
of the Australian National University in Canberra, who visited the area recently, say it is seismically 鈥減articularly active, but you don鈥檛 hear much about it because it is relatively sparsely populated鈥�. There have been dozens of quakes there in the last month, with over 40 greater than magnitude 4.5 in the preceding seven days.
According to the US Geological Survey (USGS), there have been several major earthquakes in the region over the past decade, including a magnitude 8.1 earthquake in April 2007.
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罢辞诲补测鈥檚 struck shortly after 1 am GMT where the Australian plate is plunging below the Pacific plate along a zigzag-shaped fault, moving eastward at a rate of about 94 millimetres each year.
The USGS originally reported that the quake was about 5.8 kilometres deep, says of the University of New South Wales in Sydney. 鈥淭hat made me think 鈥榦h no, here we go again, this will be a bad one鈥�.鈥� Earthquakes as shallow as that can transmit more energy to the surface, producing more intense shaking and larger tsunamis. However, the Pacific Tsunami Warning Center in Hawaii then said , so the tsunami was weaker than first thought. The USGS now gives the depth as 28.7 km.
Arculus says our knowledge of the area鈥檚 geology was poor until recently. For example, it was thought there were no submarine volcanoes along the plate boundary 鈥� until half a dozen were found in 2002. 鈥淭he volcanoes and seismicity are part of the same phenomenon,鈥� says Arculus.
Along with the volcanoes, there are mineral-rich hot springs. 鈥淭hese hot springs have vents that put out black smoke, which is full of gold and copper,鈥� says Arculus. The Canadian company Nautilus Minerals has an exploration license for the area and plans to begin mining the vents later this year. Australia鈥檚 Bluewater Metals also has an exploration license.
In its , Nautilus says local communities have expressed concern that deep-sea mining could trigger earthquakes and tsunamis by releasing stress that has built up in the sea bed. However the company says this is unlikely, arguing that stresses cannot build up because the area is so seismically active.
