How Do Tsunamis Work?

Hiroshi Kawahara, AFP/Getty Images
Hiroshi Kawahara, AFP/Getty Images

Tsunamis have been wreaking havoc on the world's coastlines for centuries. Since 1850 alone, tsunamis have been responsible for taking 420,000 lives and causing billions of dollars in damage. How do these monster waves work?

DON'T CALL IT A TIDAL WAVE

Tsunamis have nothing to do with the wind-generated waves we're used to seeing, or the tides—they’re a set of ocean waves caused by the rapid displacement of water. Most commonly, this happens when large underwater earthquakes push up the seabed; the larger and shallower the earthquake, the bigger the potential tsunami. Once generated, the waves split: A distant tsunami travels out into the open ocean, while a local tsunami travels toward the nearby coast. The speed of the waves depends on the depth of the water, but typically, waves roll across the ocean at speeds between 400 and 500 mph.

It’s not only the method of generation that differentiates tsunamis from wind-generated waves. On average, wind waves have a crest-to-crest wavelength—the distance over which the wave’s shape repeats—of approximately 330 feet and a height of 6.6 feet. A deep ocean tsunami will have a wavelength of 120 miles and amplitude (the distance from the peak of the wave to its trough) of only about 3.3 feet. This is why tsunamis are difficult to detect in the open ocean.

As a tsunami approaches the shore, the wave compresses: Its speed and wavelength decrease while its amplitude grows enormously. Most waves arrive on-shore not as a huge wave but as a fast-moving tidal bore that floods the shoreline. However, if the trough of the wave arrives before the ridge, or peak, the sea will recede from the shore, exposing normally submerged areas, as the trough builds into a ridge. This can serve as a brief warning that a tsunami is about to occur.

Other causes of tsunamis include underwater landslides and explosions. Another type of wave, called a mega-tsunami, is caused by above-water landslides or glacier calving. The largest recorded mega-tsunami struck in Alaska’s Lituya Bay in 1958; an earthquake triggered a landslide that displaced so much water that the waves created were 470 feet taller than the Empire State Building.

MONITORING WAVES

Like earthquakes, tsunamis can’t be predicted—but that doesn’t mean scientists aren’t trying to figure out ways to warn people before the flooding starts. Using a system of buoys called DART—Deep-Ocean Assessment and Reporting of Tsunamis—researchers can monitor ocean wave height in real time. When an earthquake occurs that scientists believe is likely to trigger a tsunami, these strategically placed buoys send reports on sea level change back to tsunami warning centers. There, scientists use that data to create a model of the potential tsunami’s effects and decide whether to issue a warning or make populations evacuate.

In the 2012 action film Battleship, the DART system took a star turn. Director Peter Berg used it as a method of creating the game’s iconic grid. (The Hollywood version of DART is much more robust than the real-world version, which has just 39 buoys.)

LOCATION, LOCATION, LOCATION

Tsunamis are mostly generated by quakes that occur in subduction zones: areas where denser oceanic plates slide underneath lighter continental plates, causing vertical displacement of the seafloor and water column above it. The majority of the world's subduction zones are in the Pacific Ocean bordering Oceania, Asia, North America, and South America. This highly unsettled loop is nicknamed the "ring of fire" for its concentration of geologic upheavals.

Because the Atlantic Ocean has far fewer subduction zones than the Pacific, Atlantic tsunamis are rare, but possible. The most likely cause would be an earthquake creating a submarine landslide that would displace a huge volume of water and trigger the wave.

In 2001, geophysicists Steven N. Ward and Simon Day suggested that an Atlantic mega-tsunami could be generated by a massive landslide off La Palma, the most active volcano in the Canary Islands archipelago. The theory was based on modeling a number of worst-case scenarios, the authors said. Others have argued that the danger is overblown.

Pioneering Heart Surgeon René Favaloro Is Being Honored With a Google Doodle

Dr. René Favaloro (left) pictured with colleague Dr. Mason Sones.
Dr. René Favaloro (left) pictured with colleague Dr. Mason Sones.
The Cleveland Clinic Center for Medical Art & Photography, Wikimedia Commons // CC BY 4.0

Argentinian heart surgeon René Favaloro is the subject of today’s Google Doodle, which features a sketched portrait of the doctor along with an anatomical heart and several medical tools, The Independent reports.

The renowned doctor was born on this day in 1923 in La Plata, the capital of Argentina’s Buenos Aires province, and pursued a degree in medicine at La Plata University. After 12 years as a doctor in La Pampa, where he established the area’s first mobile blood bank, trained nurses, and built his own operating room, Favaloro relocated to the U.S. to specialize in thoracic surgery at the Cleveland Clinic.

In 1967, Favaloro performed coronary bypass surgery on a 51-year-old woman whose right coronary artery was blocked, restricting blood flow to her heart. Coronary bypass surgery involves taking a healthy vein from elsewhere in the body (in this case, Favaloro borrowed from the patient’s leg, but you can also use a vein from the arm or chest), and using it to channel the blood from the artery to the heart, bypassing the blockage. According to the Mayo Clinic, it doesn’t cure whatever heart disease that caused the blocked artery, but it can relieve symptoms like chest pain and shortness of breath, and it gives patients time to make other lifestyle changes to further manage their disease.

Favaloro wasn’t keen on being called the “father” of coronary bypass surgery, but his work brought the procedure to the forefront of the clinical field. He moved back to Argentina in 1971 and launched the Favaloro Foundation to train surgeons and treat a variety of patients from diverse economic backgrounds.

Favaloro died by suicide on July 29, 2000, at the age of 77, by a gunshot wound to the chest. His wife had died several years prior, and his foundation had fallen deeply into debt, which Argentinian hospitals and medical centers declined to help pay, The New York Times reported at the time.

“As a surgeon, Dr. Favaloro will be remembered for his ingenuity and imagination,” his colleague Dr. Denton A. Cooley wrote in a tribute shortly after Favaloro’s death. “But as a man ... he will be remembered for his compassion and selflessness.” Today would have been his 96th birthday.

[h/t The Independent]

Forget Lab-Grown Meat—You Can Now Buy Lab-Grown Ice Cream

Deagreez/iStock via Getty Images
Deagreez/iStock via Getty Images

Even though “dairy-free” doesn’t necessarily mean “healthier,” it’s still a necessary disclaimer for dairy-free people who are screaming for ice cream. And between veganism, lactose intolerance, and other dietary dairy restrictions, the race is on to create an ice cream for the masses that doesn’t taste like chalk, chemicals, or sadness.

Bay Area startup Perfect Day may have just pulled ahead of the competition. Today, Fast Company reports, it released three flavors of dairy-free ice cream—Vanilla Salted Fudge, Milky Chocolate, and Vanilla Blackberry Toffee—that contain the same proteins found in cow dairy, but grown in a lab from engineered yeast and DNA. Since those proteins contribute greatly to the rich texture and taste of ice cream that we love so much, Perfect Day’s products are supposedly indistinguishable from the real thing.


View this post on Instagram

A post shared by Perfect Day (@perfectdayfoods) on

The co-founders, vegan bioengineers Ryan Pandya and Perumal Gandhi, got the idea from their experience in medicine, where fermentation is used to grow things in a lab all the time. “The two of us started scratching our heads and wondering, what if we just apply that same exact technology that’s been around for half a century to make the world’s most in-demand, highest-quality protein?” Pandya explained to Fast Company.

Their lactose-, dairy-, and gluten-free vegan ice cream, which they’ve been working on for five years, includes the dairy proteins casein and whey, as well as plant-based fats and sugar. If you're dairy-free because of a casein or whey allergy or sensitivity, you should treat this ice cream like you would any other foods containing dairy, and heed the "Contains milk protein" disclaimer on Perfect Day products.

Lab-grown dairy has environmental benefits too, considering that cows and other livestock are major culprits of greenhouse gas emissions. Pandya and Gandhi hope to sell their proteins to large-scale food manufacturers, and have teamed up with Archer Daniels Midland, an Illinois-based food processing company, to increase production.

Though it seems like a scoop or two of this ice cream might be the recipe for a perfect day, that wasn’t the inspiration behind the company’s name—the founders stumbled upon a study in which scientists discovered that cows produced more milk when listening to music, and one of the most successful songs was Lou Reed’s “Perfect Day.” “As a company on a mission to make cows, people, and the planet happier, it seemed like a perfect fit,” the website says.

Can’t wait to taste the magic? You can purchase all three flavors in a three-pint bundle for $60 here.

[h/t Fast Company]

SECTIONS

arrow
LIVE SMARTER