Deadly 'Ring of Fire' quakes not linked: experts

The only link between deadly earthquakes in Indonesia and the South Pacific was the stretch of seismic activity where they struck -- the site of most of the world's quakes, experts said on Thursday.

The only link between deadly earthquakes in Indonesia and the South Pacific was the stretch of seismic activity where they struck -- the site of most of the world's quakes, experts said on Thursday.

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They said Tuesday's 8.0-magnitude quake that hit the remote Pacific islands of Samoa and Western Samoa and a 7.6 tremor the following day in Indonesia were along the "Ring of Fire" on the Australian tectonic plate, but too far apart for any connection.

"They were 10,000 kilometres (6,200 miles) apart," Bill Fry, a seismologist at GNS Science in New Zealand, told AFP. "You can get quakes that are close temporally and spatially as one transfers stress to another place against the fault but that's not possible this far apart," he added.

Earthquake frequency needs to be studied over a period of thousands of years to establish patterns, Fry said, and it was impossible to draw conclusions about a cluster of seismic events occurring over a few days.

"The frequency at which we have large quakes over a period of days, or even weeks and months, is quite chaotic," he added.
The Ring of Fire reaches from Indonesia to the coast of Chile in a 40,000 kilometre (25,000 mile) arc of seismic violence that unleashes earthquakes and volcanoes around the Pacific rim almost every day.

Professor Gary Gibson, from the Royal Melbourne Institute of Technology's Seismology Research Centre in Australia, agreed that it was impossible to draw any connection between the two. "There is no known mechanism to connect them," he told AFP.

"What's happening is perfectly normal... Earthquakes often seem to cluster more than they actually do but that is mainly just a psychological perception because you get a big one and then become more alert to others."

Geologists worried that the Indonesian city of Padang, where Wednesday's quake left upwards of 1,000 people feared dead, was vulnerable to more quakes and tsunamis however.

There was also the possibility that the seismic activity could set off eruptions, with three big volcanoes in Indonesia's West Sumatra -- Merapi, Talang and Tandikat.

"There seems to be a relationship between volcanoes and earthquakes. They are all part of the same tectonic system," Gibson said.