Taipei skyscraper may have triggered quakes
(China Daily)
Updated: 2005-12-03 06:29

And it is this exceptional downward stress that Lin thinks may have caused the extra earthquakes.

"I think that the considerable stress might be transferred into the upper crust due to the extremely soft sedimentary rocks beneath the Taipei basin," he said in his paper, published in the journal Geophysical Research Letters.

"Deeper down this may have reopened an old earthquake fault."

Other experts are more cautious about blaming the skyscraper for the earthquakes.

John Vidale, an earthquake expert at the University of California in Los Angeles, said: "A building will change the stress on the ground under the building, but this probably won't reach down to around 10km, the level where the earthquakes occurred."

Zygmunt Lubkowski, an earthquake analyst for the engineering firm Arup, is concerned at the lack of data.

"Earthquakes occur on timescales of thousands to millions of years. From just 10 years of earthquake data it is hard to tell if the extra earthquakes are just noise in the signal or due to the building."

Many engineers and scientists are more perturbed about the impact of other types of construction. "It is well known that man can induce earthquakes from things like mining, building reservoirs and extracting oil and gas, where a large load acts over a large area," Lubkowski said.

Compared with dams and underground waste deposits, skyscrapers such as Taipei 101 are mere pinpricks on the Earth's surface.

"It is a point load which is probably going to be insignificant at depth," Dr Leonardo Seeber, a geologist from the Lamont Doherty Eearth Observatory in New York, said.

The Guardian

(China Daily 12/03/2005 page1)