Taipei skyscraper may have triggered quakes
Updated: 2005-12-03 06:29
Taipei 101 is a building with a lot to boast about. Standing 508 metres high, it is the world's tallest. And at 700,000 tons, it must be among the heaviest.
But the sheer size of the Taiwan skyscraper has raised unexpected concerns that may have far-reaching implications for the construction of other buildings and man-made megastructures. Taipei 101 is thought to have triggered two recent earthquakes because of the stress that it exerts on the ground beneath it.
Taipei 101, the world's tallest building. [newsphoto]
According to the geologist Cheng Horng Lin, from the National Taiwan Normal University, the stress from the skyscraper may have reopened an ancient earthquake fault. And it is not just skyscrapers that are a problem. Dams and underground waste deposits may also cause rumblings if they become too large.
Before the construction of Taipei 101, the Taipei basin was a very stable area with no active earthquake faults at the surface. Its earthquake activity was similar to parts of the UK, with micro-earthquakes (less than magnitude 2) happening about once a year.
However, once Taipei 101 started to rise from the ground, things changed.
Lin said: "The number of earthquakes increased to around two micro-earthquakes per year during the construction period (1997 to 2003).
"Since the construction finished there have been two larger earthquakes (magnitude 3.8 and 3.2) directly beneath Taipei 101, which were big enough to feel,"
Using the construction information, Lin has calculated how much pressure Taipei 101 exerts on the ground. The weight of steel and concrete came to more than 700,000 tons. This is spread over an area of 15,081 square metres, meaning that it exerts a huge pressure of 4.7 bars on the ground below. "The construction of Taipei 101 is totally different from many other high-rise buildings because it used hybrid structures made of both concrete and steel, to give it added protection from earthquakes and fire. Therefore it has a huge vertical loading on its foundation," Lin said.