Zipingpu Dam May Have Triggered the Sichuan Quake

bfwebster writes "An article in the Telegraph (UK) raises an interesting question: was the massive (7.9) Sichuan earthquake that wracked China last year and left millions homeless caused by ground stresses following the completion of the Zipingpu dam? As the article notes, 'The 511-ft-high Zipingpu dam holds 315 million tonnes of water and lies just 550 yards from the fault line, and three miles from the epicenter, of the Sichuan earthquake. Now scientists in China and the United States believe the weight of water, and the effect of it penetrating into the rock, could have affected the pressure on the fault line underneath, possibly unleashing a chain of ruptures that led to the quake.'" The Sichuan region is earthquake-prone, but has not seen anything as large as the 7.9-magnitude quake for perhaps millions of years. The Chinese government denies any connection between the dam and the earthquake and seems to be actively obstructing the access of scientists who want to investigate. The article concludes, "There is a history of earthquakes triggered by dams, including several caused by the construction of the Hoover Dam in the US, but none of such a magnitude."

Comments

It would have likely occurred anyway

[EmbeddedJanitor]

The dam might have just brought the event forward a year or two. Fault lines are natural stress relief areas anyway.

As with all things geological, there are a lot of unknown variables, hence the "could", "might" and other diluting terms.

Re:It would have likely occurred anyway

[Gat0r30y]

I suspect that when as much energy as was released in that particular quake gets released, it was gonna get out one way or another. But building the dam where they did couldn't have helped.

Re:It would have likely occurred anyway

[corsec67]

The dam might have just brought the event forward a year or two.

Or made it much more intense. Maybe without the dam and lake instead of one large earthquake it would have been a series of smaller earthquakes.

Adding a large weight almost on top of a fault is definitely going to influence it, flexing the Earth and altering the stresses in the fault.

Re:It would have likely occurred anyway

[Fluffeh]

but the proper way to look at it is the earthquake brought the geology back to a neutral point

Why on earth would you say that? Earthquakes don't bring geology to neutral points. They happen when the earth gets past critical point.

I can't think of a totally slashdot car analogy, but here is a good analogy of earthquake causes and how it works geologically that at least includes a car.

Think of a piece of bungee cord 10 meters in length. You tie one part to the tow-ball of a car, and hold the middle of the cord. This means there is five meters of slack cord past the point where you are holding. Now, the car very very slowly starts to drive away from you, and the tension in the cord slowly grows. You holding onto the cord with all your might represents the pressures on the fault line. Sooner or later however, the pull on the cord will be too much, and it will slip in your hand. Now, you don't totally let go however. It might slip an inch or two, just barely enough so that the force of your hand holding it once again overcomes the force of the pull in the cord - but there is still a lot of tension in the cord. When the car moves away far enough again, there will be another slip of a small distance again and again.

This is how fault lines work. When there is a quake, it doesn't go back to a neutral point. It goes back to a point which is lower than the critical point that caused the earthquake.

Re:It would have likely occurred anyway

[Anonymous Coward]

Suggest you better research the coffee spill incident. Car wasn't moving, complaints about temp filed more than once, much hotter than surrounding area restaurants, woman required skin grafts to repair damage and only sued for cost of medical bills after McD's blew her off. Lots of details glossed over concerning that incident but considering just how hot it was and the damage it did I don't think awarding ONE day's worth of coffee sales was that bad of a restitution... and that was later overturned.

There are certainly shitty lawsuits but THAT one was pretty deserved I think and a poor example despite your trying to be funny about it.

Re:I feel a bad movie based on this where need to

[Chabo]

Sir Ranulph Fiennes (the famous arctic explorer, among other things) was actually kicked out of the SAS for destroying a dam using stolen explosives. You can google for more detailed accounts of the story, but here's one:

http://www.independent.co.uk/student/career-planning/getting-job/my-first-job-explorer-sir-ranulph-fiennes-was-an-sas-officer-420601.html

the government is blameless

[circletimessquare]

let's say they know dams cause earthquakes. ok, so there will be some minor earthquakes. but 7.9? no one is going to predict anything that large

still, let's assume the dam is still the trigger for the 7.9 earthquake. emphasis on trigger. its going to happen someday anyway

if they never built the dam, we'd be talking about the 7.9 or 8.3 sichuan earthquake of 2031 or 2102

Re:Prediction

[peragrin]

not to dodge your sarcasm, but the scientific findings are vague enough to blame the entire quake on Bush bombing people in iraq.

you never know what that one last MOAB will really do what with the butterfly effect and everything.

also if a quake hasn't happened in a million years then it just might be under a lot of stress, that doesn't easily go away.

How do they know it's never happened before?

[Hans Lehmann]

The Sichuan region is earthquake-prone, but has not seen anything as large as the 7.9-magnitude quake for perhaps millions of years

Would a 7.9 quake, although large by earthquake standards, even leave evidence that lasted more than, say, 1000 years? You might be able to tell if you took a cross section of the entire fault line, I suppose, but not all fault lines are known. A L.A. city geologist found a previously unknown (but not currently active) fault under the house of a friend of mine when he was having some drainage work done; new ones are discovered all the time.

NASA math at work. And yes,IAANB*

[rts008]

Maybe they can get this drilling crew on the mission to save the day!

All humour aside, most people have no clue about the energy levels and destructive power available to natural forces, just on our world. (ie:water) Even engineers can fall prey to their preconceptions at times, if they are not diligent. Water is a powerful force, in scale.

Most people perceive the Earth as a solid/stable surface to build on(dig to 'bedrock' for the foundation, etc...), frequently forgetting Earth more resembles a poultry egg: relatively thin shell covering/encasing a liquid center...and just as fragile on scale.

At our most terrible destructive level available technologically to humans today, we are still just 'wannabe' punks in the big picture. Actually, I would argue that communication tech is the most powerful weapon/tech we have devised to date.

*(IAANB) I Am A NASA Brat![clarification of subject line]-just could not pass this one up. And NOT trying to pick on engineers, who have demanding job requirements, but there is a good reason to put erasers on pencils! :-)

Sorry if this was more than you bargained for trying to make a 'funny', but you did raise a valid point! :-)

Re:Prediction

[Malc]

Yes, that's so true. The changes that China has gone through in the last 100 years are staggering. Edgar Snow's Red Star Over China gives a fantastic account of what China was like during the Communist Revolution. It brought them forward a millennia in a few years, spreading education, and raising standards for 100 of millions of poor Chinese peasants. But that still left China far behind what we consider a well developed country. Of course, the Great Leap Forward and Cultural Revolution didn't really help. Then again in the last ten or fifteen years, it's almost as if China has come forward another millennia, where cities like Shanghai are fairly easy to live in as Westerner. The people there are now beginning to resist change for this reason. Want to build a new Maglev line to Hangzhou or high speed rail link to Beijing? The people organised together and forced the government to re-route it via somebody else's neighbourhood. Out in the country though, people still put up with being relocated because their lives haven't changed as fast and are some way behind.