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Quakes, volcanoes 'unrelated'
29/05/2006 09:52 - (SA)
Indonesia - The Asia-Pacific rim is rumbling.
While earthquakes are common and even expected along the belt that circles the Pacific Ocean, the Asian side of the rim has been struck particularly hard in the last 18 months by strong seismic activity.
In December 2004, an undersea quake triggered the tsunami that killed 131 000 people. Last October, Pakistan was struck by a 7.6-magnitude quake that killed 80 000 people.
Numerous smaller temblors rocked the rim until Saturday, when a 6.3-magnitude earthquake hit central Indonesia, causing nearly 5 000 deaths in the same area that has been bracing for a possible full-scale volcanic eruption.
A day later, two powerful earthquakes struck the South Pacific nations of Papua New Guinea and Tonga.
Quakes unrelated
But while the strength and frequency of the quakes rattling the region raises fears of more disasters, experts say they are likely unrelated.
The Pacific rim, the belt that circles the edges of the ocean from the Americas to Asia and the South Pacific islands, is the site of most of the world's seismic activity, as there are long fault zones that are constantly pushing the ocean floor beneath the continents. Earthquakes are common.
Quake may trigger volcanic eruption
But Saturday's 6.3-magnitude quake struck central Indonesia as it was already fearfully monitoring Mount Merapi, a volcano that has been rumbling and spewing smoke and lava for weeks. Soon after the temblor, the 3 000-metre Merapi spewed hot clouds in a loud burst and sent debris cascading some 3.5km down its western flank.
Many fear that the quake will trigger the feared eruption of one of the world's most active volcanoes. Mount Merapi, which means "Fire Mountain," has erupted scores of times in the last 200 years, often with deadly results.
Earlier this month, residents in the danger zone had been ordered to evacuate, though many recently returned to tend crops, milk cows and feed livestock.
Quake 'will impact volcano'
Bambang Dwiyanto, head of the geological department at Indonesia's energy and mineral ministry, said there were no links between Saturday's quake and the increased activity at Merapi, but he said the quake could still set off a larger eruption.
"The impact of the earthquake ... will influence the activities of Mount Merapi, particularly in the lava dome," he said, referring to a build up of lava near the top of the volcano's crater.
Clive Oppenheimer, of the University of Cambridge's Volcanology Group, said external factors could trigger or accelerate eruptions.
"It's certainly possible a good shake from the earthquake could destabilise" the lava dome, Oppenheimer said.
Other seismic activity
Barry Hirshorn, a geophysicist with Hawaii's Pacific Tsunami Warning Centre, said the Papua New Guinea and Tonga quakes posed no risk of a Pacific-wide tsunami and were unlikely to be related.
"They're probably unrelated, they just happened at the same time," he said.
Other experts have the same opinion on the string of recent major seismic rumblings, saying the quakes and volcanoes are not likely related.
"This area is pretty active seismologically," said Anthony Guarino, a seismologist at CalTech Seismological Laboratory in Pasadena, California.
"The earthquake that caused the tsunami was not in same area as this, so that quake probably had no bearing on" the Indonesia quake.
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