Quakes, eruption sign of land on move

While the Australian continent is edging its way towards the north-east of the globe at a rate of about seven centimetres a year, the islands of the Pacific are moving towards them in a westerly direction at much the same speed. The result: an underwater volcano erupting on Monday in the South Pacific, an earthquake shaking Victoria on Wednesday, and a much larger quake near Tonga that caused a tsunami alert in the region. The events are linked by the fact that the country sits in the middle of a large tectonic plate, the Indian-Australian plate, which is crashing into the Pacific Plate that lies beneath the Pacific Ocean. A build-up of stress in the plate was released near Korumburra, to the south-east of Melbourne, in a magnitude 4.6 earthquake on March 6. While not surprising, a second earthquake of the same size at the same spot on Wednesday afternoon was an "unusual" event for Australia. The first earthquake transferred new stresses further along the geological fault line, which were eventually released in last week's tremor.