Did Tasmanian Tremor
Act As Tsunami Catalyst?

Indo-Asian News Service
SYDNEY/COLOMBO (IANS) -- Did the smaller and earlier tremor last week off Tasmania in Australia trigger the tsunami that devastated many areas in South and Southeast Asia.
An Australian seismologist said the Indo-Australian tectonic plate had shifted, triggering first the smaller earthquake off the Tasmanian coast last Thursday and then Sunday's catastrophic one.
Geoscience Australia seismologist Cvetan Sinadinovski said the initial earthquake, 700 km southeast of Hobart, might have been the catalyst for the devastating tremors to hit Indonesia, but it was not a direct cause.
There are 12 plate boundaries on earth that move around. Earthquakes take place when these plates collide.
"This earthquake in Indonesia is on the same plate as the earthquake near Tasmania. It just happened on the other side, where the Australian plate collides with the Philippine plate," Sinadinovski said.
"It is not uncommon that an earthquake on one side of a plate would trigger an earthquake on the other side," The Australian daily quoted him as saying.
Indonesia was a hotspot for earthquake activity because that is where three of the earth's tectonic plates meet, Sinadinovski said.
The Indo-Australian plate moves about seven centimetres north each year, putting enormous pressure on the points where it connects with the Philippine and China plates.
Sinadinovski said Sunday's earthquake was the release of energy accumulated during the latest plate collisions.
Although Indonesia was the country closest to the earthquake's epicentre, Sri Lanka was the worst hit by the subsequent tidal waves.
"Because of the earthquake's mechanism and the orientation of the islands, which form certain channels in the water, Sri Lanka was in the direct path of the generated waves," he said. "It was the focus point."
Meanwhile, C.B. Dissanayake, senior geologist at Sri Lanka's Peradeniya University, warned that the island nation was no longer safe from earthquakes as a new plate boundary phenomenon was being formed south of the country.
Sri Lanka is located inside the Indo-Australian plate but "it is breaking up right near the south of Sri Lanka. Therefore, this kind of geological change may cause earthquakes," the Daily News newspaper quotes him as saying.
"Sri Lanka is no longer safe from earthquakes. A recent research conducted by James Cochran, a scientist at the Doherty University in the US has also predicted this new plate phenomenon developing in south of Sri Lanka", according to Dissanayake.
Sinadinovski said the timing of the earthquakes was coincidental and not at all cyclic.
"Earthquakes are not connected to the weather or to the calendar year. They are connected to long geological processes, the Australian reported.
Thursday's Australian quake, which at its epicentre measured 8.1 on the Richter scale, hit at the Macquarie Rise in the Pacific Ocean, seismologists said.
Its impact was felt about 900 km to the northwest, on the Tasmanian coast, but apparently not 400 km to the south on remote Macquarie Island, where Australian scientists slept through it.
Sinadinovski said buildings in Tasmania shook for up to 15 seconds, but no injuries were reported.
And there was little danger of significant structural damage to buildings from a quake so far out to sea.
"If it happened underneath a population centre in Australia, this would probably have destroyed a whole city," Sinadinovski said.
©Copyright 2001-2004 IANS India Private Limited.



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