Engineers Have Figured Out How the Leaning Tower of Pisa Withstands Earthquakes

iStock
iStock

Builders had barely finished the second floor of the Tower of Pisa when the structure started to tilt. Despite foundational issues, the project was completed, and eight centuries and at least four major earthquakes later, the precarious landmark remains standing. Now, a team of engineers from the University of Bristol and other institutions claims to have finally solved the mystery behind its endurance.

Pisa is located between the Arno and Serchio rivers, and the city's iconic tower was built on soft ground consisting largely of clay, shells, and fine sand. The unstable foundation meant the tower had been sinking little by little until 2008, when construction workers removed 70 metric tons of soil to stabilize the site. Today it leans at a 4-degree angle—about 13 feet past perfectly vertical.

Now researchers say that the dirt responsible for the tower's lean also played a vital role in its survival. Their study, which will be presented at this year's European Conference on Earthquake Engineering in Greece, shows that the combination of the tall, stiff tower with the soft soil produced an effect known as dynamic soil-structure interaction, or DSSI. During an earthquake, the tower doesn't move and shake with the earth the same way it would with a firmer, more stable foundation. According to the engineers, the Leaning Tower of Pisa is the world's best example of the effects of DSSI.

"Ironically, the very same soil that caused the leaning instability and brought the tower to the verge of collapse can be credited for helping it survive these seismic events," study co-author George Mylonakis said in a statement.

The tower's earthquake-proof foundation was an accident, but engineers are interested in intentionally incorporating the principles of DSSI into their structures—as long as they can keep them upright at the same time.

Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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China Is Now Home to What May Be the World’s Most Stunning Bookstore

The best place to get lost.
The best place to get lost.
Shao Feng/X+Living

Anywhere with books for sale is automatically a lovely place to be, but this new bookstore in southwest China just upped the ante with its jaw-dropping display of shelves.

The shop, located in Dujiangyan City, Sichuan, was designed by Li Xiang and her architectural firm X+Living. As Li mentioned on Instagram, she drew inspiration from Dujiangyan’s ancient irrigation system, which uses the rivers running in and around the city. You can definitely see its influence on her work; the towering arches and winding staircases evoke images of flowing water, and the mirrored ceiling makes the room seem infinite. ArchDaily points out that the curved display tables on the black tiled floor even look like boats in deep, placid water. Taking in the entire scene elicits a similar sense of awe that you might feel when observing a natural landscape.


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A post shared by Li Xiang | X+LIVING (@xlivingart) on

Then, there are the books themselves. While shelves stretch up to the ceiling (and seemingly beyond, thanks to those mirrors), visitors don’t have to worry about certain volumes being much too far to reach. The highest “shelves” are actually just wallpaper printed to look like bookshelves. According to designboom, the store also houses a children’s reading area, complete with green bamboo bookshelves, pictures of pandas, and bright-colored cushions.

It’s not the first time X+Living has created a space for book lovers. The Dujiangyan shop is the latest in the firm’s Zhonghuge series of bookstores around China, including locations in Beijing, Ningbo, Guiyang, and Chongqing. There are certain recurring design elements—like mirrored ceilings, curved shelves, and archways—but each has its own distinct style.

While you’re waiting for a chance to explore one of Li Xiang’s magical buildings, find out which bookstore is your state’s best one here.

[h/t designboom]