02 December, 2005

Skyscraper that may cause earthquakes

Guardian Unlimited | Science | Skyscraper that may cause earthquakes


Using the construction information, Dr Lin has calculated how much pressure Taipei 101 exerts on the ground. The weight of steel and concrete came to more than 700,000 tonnes. This is spread over an area of 15,081 square metres (3.7 acres), meaning that it exerts a huge pressure of 4.7 bars on the ground below. "The construction of Taipei 101 is totally different to 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," says Dr Lin.

And it is this exceptional downward stress that Dr 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. Deeper down this may have reopened an old earthquake fault," suggests Dr Lin in his paper, published in the journal Geophysical Research Letters.

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


BD said...

I know nothing about geology but it sounds kind of far-fetched. No matter how tall or big a building is it is still but a tiny, minute presence compared to the huge earth it stands on.

Emirati said...

That remains to be seen, the coastal fault here isnt as active as says some of the asian faults, and there remains to be little geological data here presently.

BuJ said...

With all due respect to Dr Lin his arguments hold no water. The building 101 he mentions (which is the tallest in the world, since Burj Dubai has not been completed yet) exerts only 4.6 bars of pressure. This is nothing! The atmospheric pressure is 1 Bar, and guess what, when you dive 46 m down in the sea that is also at 4.6 bar!!!

Does that mean that all seas deeper than 46m will contribue to earthquakes?

Stone is denser than water. How about mountains taller than 46 m?

Perhaps we should blame Jabal Hafeet for the quake... it's at 1000 m, thus puts 100 bar of pressure on the base of the mountain.

Slagothor said...

You're right, Buj: 4.6 bar is 460 kPa, or not even 0.5 MPa. When I was studying rock mechanics for my degree in mining engineering we often talked about stresses in the order of GPa, or thousands of MPa. Go more than 20 or 30 metres deep in a rock formation, and any additional stress caused by builing loads is dwarfed into insignificance. And as was mentioned in the article, earthquakes occur several kilometres below the surface.

BuJ said...

slagothor.. aha.. a scientist!
actually i did a quick check with a fellow engineer and we found that just the self weight of the SLABS of taipei 101 would be equivalent to 500 bar.. which makes me think that the 4.6 bar given by the Dr Lin is absurd!

remember this is excluding the weight of the people in it and cladding, columns, facade etc...

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