FYI: Can Humans Trigger Earthquakes?

Yes. We drill into the earth to mine for gas, oil and minerals and construct massive dams and, as a result, have caused at least 200 quakes of more than 4.5 magnitude in the past 160 years, says Christian Klose, a researcher at Columbia University who studies man-made quakes.

The best-known case is the earthquake caused by the Zipingpu Dam, in China’s Sichuan province, in 2008. Zipingpu held 42.3 billion cubic feet of water, the weight of which precipitated what Klose says is the largest human-triggered earthquake to date: a 7.9-magnitude quake that killed nearly 80,000 people. Klose estimates that Zipingpu, with nearly 320 million tons of water pressing down on a fault line, contributed enough stress to trigger the quake through a process called impoundment. “If you push your finger on top of a paper plate, the plate will bend,” he says. “That same effect works on all the tectonic plates on the Earth’s crust.” The quake occurred two years after the dam’s completion, and its epicenter was a mere three miles from the structure.

Authorities in Basel, Switzerland, shut down the city’s geothermal plant after a 3.4 quake in 2006. Tapping geothermal energy involves boring into rock miles beneath the Earth’s crust in search of steam as a source of energy. Engineers in areas without much water, such as Basel, sometimes create boreholes by way of hydraulic fracturing, or “fracking,” which involves forcefully injecting water to create fissures. Fracking can generate small tremors, but the real damage may happen as excess liquid pools in the cracks between rocks, making them less stable. Although dams have caused some 76 earthquakes, mining is responsible for at least 137 earthquakes, over half the number of man-made quakes to date.

In 1989 a 5.6-magnitude earthquake hit Newcastle, Australia, the direct result of coal mining. Extracting millions of tons of coal added stress to the fault lines, but the real danger resulted from the water that was extracted during mining. For each ton of coal produced, Klose estimates, 4.3 times as much water was pumped out of the ground, a necessary step to prevent flooding inside the mine. But removing so much water dramatically altered the stability of the earth surrounding the mine. Klose says the earthquake caused $3.5 billion in damage-an amount that nearly equaled the profit of all the coal produced by the mine over its 200-year history.

Have a science question you’ve always wondered about? Send an email to fyi@popsci.com

Error’d: $$.$$

Error’d: $$.$$: “

“The little sticker next to the ATM said that the fee shown on the screen would be assessed,” writes Matt, “I guess if I have to ask what $$.$$ is, I can’t afford it.”

 

“I really am not sure what to make of this,” Nick Hartley wrote, “do I owe them nothing or not?”

 

“I haven’t known anyone to have this type of tree in their yard,” writes Brian, “I might need to do more research before getting it.”

 

“Oh, makes sense, I can’t install Office Project 2011 32-bit, so let me switch to the 64-bit edition,” Aaron wrote, “… well then. They could have just said I couldn’t have it in the first place.”

 

“This is from a company with direct access to my credit card account,” notes Adam Thompson.

 

Craig Mulvaney spotted this at an ATM in Newcastle.

 

“Apparently, my payment is 2011 years overdue,” writes Petr O., “I wonder what the interest for $0 USD is going to be…”

 

Paul Collins writes, “I just finished installing Lenovo Fingerprint Software… do I install Lenovo Fingerprint Software?”

 

“I hope it’s not that important,” writes Brendan L.

 


 

(Via The Daily WTF.)

Bias Lighting

Bias Lighting: “

I’ve talked about computer workstation ergonomics before, but one topic I didn’t address is lighting. We computer geeks like it dark. Really dark. Ideally, we’d be in a cave. A cave … with an internet connection.

You-read-my-doormat

The one thing that we can’t abide is direct overhead lighting. Every time the overhead light gets turned on in this room, I feel like a Gremlin shrieking Bright light! Bright light! Oh, how it burns!

But there is a rational basis for preferring a darkened room. The light setup in a lot of common computing environments causes glare on the screen:

 

If your room’s lit, as most are, by fittings hanging from the ceiling, you’ll be wanting to set up your monitor so that you don’t see reflections of the lights in it. The flat screens on many modern monitors (like the excellent Samsung I review here) help, because they reflect less of the room behind you. And anti-reflective screen coatings are getting better and better too. But lots of office workers still just can’t avoid seeing one or more ceiling fluoros reflected in their screen.

A good anti-reflective coating can reduce most such reflections to annoyance level only. But if you can see lights reflected in your screen, you can probably also directly see lights over the top of your monitor. Direct line of sight, or minimally darkened reflected line of sight, to light sources is going to give you glare problems.

Glare happens when there are small things in your field of vision that are much brighter than the general scene. Such small light sources can’t be handled well by your irises; your eyes’ pupil size is matched to the overall scene illumination, and so small light sources will appear really bright and draw lines on your retinas. The more of them there are, and the brighter they are, the more work your eyes end up doing and the sooner they’ll get tired.

 

While a darkened room is better for viewing most types of computer displays, it has risks of its own. It turns out that sitting in a dark room staring at a super bright white rectangle is … kind of bad for your eyes, too. It doesn’t help that most LCDs come from the factory with retina-scorching default brightness levels. To give you an idea of how crazy the defaults truly are, the three monitors I’m using right now have brightness set to 25/100. Ideally, your monitors shouldn’t be any brighter than a well-lit book. Be sure to crank that brightness level down to something reasonable.

You don’t want total darkness, what you want is some indirect lighting – specifically bias lighting. It helps your eyes compensate and adapt to bright displays.

 

“[Bias lighting] works because it provides enough ambient light in the viewing area that your pupils don’t have to dilate as far. This makes for less eyestrain when a flashbang gets thrown your way or a bolt of lightning streams across the screen,” he told Ars. “Because the display is no longer the only object emitting light in the room, colors and black levels appear richer than they would in a totally black environment. Bias lighting is key in maintaining a reference quality picture and reducing eye-strain.”

Bias lighting is the happy intersection of indirect lighting and light compensation. It reduces eye strain and produces a better, more comfortable overall computing display experience.

Bias-lighting

The good news is that it’s trivially easy to set up a bias lighting configuration these days due to the proliferation of inexpensive and bright LEDs. You can build yourself a bias light with a clamp and a fluorescent bulb, or with some nifty IKEA LED strips and double-sided foam tape. It really is that simple: just strap some lights to the back of your monitors.

I’m partial to the IKEA Dioder and Ledberg technique myself; I currently have an array of Ledbergs behind my monitors. But if you don’t fancy any minor DIY work, you can try the Antec Halo 6 LED Bias Lighting Kit. It also has the benefit of being completely USB powered.

Of course, lighting conditions are a personal preference, and I’d never pitch bias lighting as a magic bullet. But there is science behind it, it’s cheap and easy to try, and I wish more people who regularly work in front of a computer knew about bias lighting. If nothing else, I hope this post gets people to turn their LCD monitors down from factory brightness level infinity to something a tad more gentle on the old Mark I Eyeball.

 

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(Via Coding Horror.)