15 Facts About Lava

Ulet Ifansasti/Getty Images
Ulet Ifansasti/Getty Images

Every day, the news is filled with images of the lava flows coming from Kilauea volcano in Hawaii. Previously obscure terms like laze (lava and haze), vog (volcanic and smog/fog), and pahoehoe and a'a (types of lava flows) are becoming part of the lexicon. But how much do you really know about hot molten rock? Here are 15 fascinating facts about lava.

1. LAVA IS MAGMA ABOVE GROUND.

Magma describes molten rock when it's below the surface, while lava describes molten rock after it erupts. It might seem like a trivial distinction, but there are differences, especially after the liquid cools down. Both magma and lava produce igneous rocks when they cool, but underground magma tends to cool slowly and produce gigantic mineral crystals in a subset of igneous rock called plutonic. On the surface, lava tends to cool rapidly, creating tiny mineral crystals in a subset called volcanic. This means that the same source material can produce two different rocks depending on where it cooled; for example, granite and rhyolite are considered similar, except granite is plutonic, being formed underground, while rhyolite, created on the surface, is volcanic.

2. THERE ARE DIFFERENT TYPES OF LAVA …

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The vast majority of lava out there falls into one of three types: mafic, intermediate, and felsic. They're also called basaltic, andesitic, and rhyolitic lavas, respectively. (There are other types, but they're very rare.) These three lavas are distinguished by their mineral composition, viscosity, and the amount of volcanic gases—like water, carbon dioxide, and sulfur dioxide—dissolved in the liquid.

An estimated 90 percent of lava flows are mafic, consisting of around 50 percent silica (SiO2). This kind of lava has the lowest viscosity and gas content; it's the classic bright-red flow you probably picture when you think of lava. Intermediate lava, around 60 percent silica, has higher gas content and viscosity, causing it to explode. Mount St. Helens was an intermediate eruption. Even more explosive—but rare—are felsic lavas, which are 70 percent silica and have the highest gas content and highest viscosity, often exploding and producing bits of rock called tephra.

3. … AND DIFFERENT TYPES OF LAVA FLOWS.

Specifically, there are different kinds of mafic lava flow. The major types on the surface are a’a and pahoehoe, two terms that come from Hawaiian. A’a flows rapidly and loses heat, which increases the viscosity and creates a distinctive rough surface on the cooled lava flow as pieces start breaking off; the word may be from the Hawaiian for burn or stony. In contrast, pahoehoe is smooth and is frequently described as looking like a twisted rope because it moves more slowly and has a lower viscosity, so any breaks are quickly healed. The word may ultimately derive from the Hawaiian for paddle, to describe the smooth ripples paddles create in water. When an eruption occurs under the ocean, a third type called pillow appears. Aside from being underwater, pillow flows are frequently difficult to distinguish from pahoehoe.

4. THE SHAPE OF A VOLCANO IS INFLUENCED BY THE KIND OF LAVA INSIDE IT.

The more liquid mafic lava forms broad, gently sloped shield volcanoes, such as the main volcanoes on the Hawaiian islands. But that's not the only type of volcano this kind of lava can produce: Silica-rich mafic rocks can spray out in the air dramatically, landing back in the area they erupted from to create either a spatter cone, when the lava lands and remains liquid, welding the lava together, or a cinder cone, when the lava solidifies in the air and lands as rock. And if the lava comes from large cracks, it may form flood basalts (as mafic lava is also called).

The more viscous intermediate and felsic lavas produce stratovolcanoes (also known as composite), which are the classic volcano of popular imagination, like Mount Fuji, that build up steeper slopes.

Even more felsic lava leads to calderas, which are areas that erupted so violently the volcano collapsed into the now-emptied magma chamber, creating a large depression in the ground. (You may have even visited one: Yellowstone National Park, which sits above a dormant supervolcano, has a large caldera.) Very felsic lavas can also produce lava domes, which are formed when lava that has been degassed before an eruption piles up around the vent; according to the University of Oregon, the domes can occur in the craters or on the sides of stratovolcanoes and calderas—and sometimes even away from volcanoes altogether.

5. HUMANS HAVE BEEN FASCINATED BY LAVA FOR THOUSANDS OF YEARS …

The earliest depiction of a volcanic eruption was thought to be 8500 years old, located on a mural in the Neolithic settlement of Çatalhöyük, in what is now Turkey. (Some say it's not an eruption at all, but a leopard skin.) But there may be documentation of an eruption that's many thousands of years older. The cave paintings at Chauvet-Pont d'Arc, located 22 miles from France's Bas-Vivarais volcanic field, date to about 37,000 years ago. Alongside the standard cave-painting animals, there are also unusual markings that look like sprays, which led some French researchers to speculate that these are likely depictions of a previously unknown volcanic eruption.

6. … AND HAVE TRIED TO STOP IT FOR CENTURIES.

USGS via Getty Images

The earliest known attempt to stop the flow of lava was in 1669, when Mount Etna erupted on the island of Sicily. Diego Pappalardo of Catania led a group of men to open a hole in the hardened side of the lava flow; the idea was that the lava would flow out the side hole, away from their town. This was at first a success—at least for the residents of Catania. But was a potential disaster for the people of Paterno, who realized the rerouted flow was now threatening their town. They chased Diego and his men away. The hole they'd made in the hardened lava soon clogged, and the lava resumed its original path towards Catania, where it met the city wall. The wall apparently lasted several days before it failed, and lava entered the city. Sicilians had better luck in 1983 and 1992, when their attempts to divert lava flow from Mt. Etna using earthen banks and concrete blocks were moderately successful. Iceland, too, managed to contain some damage from a 1973 eruption by spraying lava with seawater.

7. WE TRIED TO BOMB LAVA INTO SUBMISSION.

In 1935, the U.S. Army bombed a lava channel on Hawaii's Mauna Loa to divert the flow heading towards Hilo. It didn't work. They tried again in 1942 during another eruption of Mauna Loa—and it still didn't work. However, a few days after the 1942 bombing, there was a natural collapse on the volcano that brought the lava flow to a halt. In theory, bombing a channel can make the lava slow down and do less damage to cities because lava moves fastest when contained in a channel or a lava tube, while lava that flows in a broad fan is much slower and cools faster.

This knowledge inspired yet more experimentation three decades later, in 1975 and 1976, when the Air Force dropped aerial ordnance on ancient lava fields on Mauna Loa to see what would happen. They found that spatter cones were particularly vulnerable to bombing. In a report, the Air Force concluded, "Modern aerial bombing has a substantial probability of success for diversion of lava from most expected types of eruptions on Mauna Loa's Northeast Rift Zone, if Hilo is threatened and if Air Force assistance is requested." Despite this assertion, the technique has never been attempted again.

8. THE CAUSE OF HAWAII'S VOLCANISM IS MYSTERIOUS.

In general, volcanoes form near the edges of plates and are side effects of plate tectonics, but Hawaii is thousands of miles from a plate boundary. To explain this and similar anomalies, geologists proposed the "hot spot" hypothesis. The idea is that a plume of extremely hot material comes from the core-mantle boundary and shoots up, punching a hole in the crust and creating islands like Hawaii. Later refinements to this theory proposed that the plume is more or less stationary, and as the crust moves over the plume it creates features like the Hawaiian island chain.

But as Earth magazine explains, this has proven easy to propose and nearly impossible to verify. Critics complain that as contradicting data has emerged, the hot spot hypothesis has become so flexible that it has stopped actually being useful. Instead, a new hypothesis ties these mid-plate features to plate tectonics. In the case of Hawaii, because the Pacific plate is subducting, or going beneath, other tectonic plates in both Asia and parts of North America, it's starting to crack—and thanks to local mantle conditions the Hawaiian volcanoes are forming. Even as the eruption is nightly news, the cause of volcanism in Hawaii is undergoing renewed debate.

9. IT'S PRETTY EASY TO OUTRUN A LAVA FLOW …

Frederic J. Brown/AFP/Getty Images

Last year, researchers from the University of Bristol looked at volcano fatalities between the years 1500 and 2017. Of more than 214,000 deaths they recorded, only 659 could be attributed to lava flows, because, they wrote, "lavas normally advance slowly, allowing escape.” The USGS says a typical mafic lava on a gentle slope flows at less than 1 mph; steep slopes and lava tubes increase that speed.

According to the Bristol researchers, what you really need to watch out for are explosions. "Sudden outbursts of very fluid lavas can cause loss of life," they wrote. "Deaths and injuries typically arise if escape routes are cut off, or as small explosions occur through interaction with water, vegetation or fuel."

Most fatalities could be attributed to "pyroclastic density currents"—basically hot gas, rocks, and ash moving at high speed—which were responsible for 60,000 deaths, or volcano-related tsunamis, which killed about the same number of people. Another nearly 50,000 people were killed by lahars, or volcanic mudflows of water and debris. The remaining deaths were caused by a mix of secondary lahars (which occur years after an eruption), tephra, avalanches, landslides, gas, flying killer rocks called ballistics, and—in nine cases—lightning.

10. … BUT THEY CAN STILL BE DEADLY.

The single largest loss of life from lava occurred in the Democratic Republic of Congo in 2002 when an estimated 100 to 130 people were killed by lava when the Nyiragongo volcano erupted. Situated near the city of Goma, the eruption displaced 250,000 people (another 150,000 are thought to have stayed) as lava flowed through the city streets and cut off parts of the town, including covering an estimated 80 percent of the airstrip at the local airport. Beyond its proximity to a major city, Nyiragongo is deadly because it's believed to have some of—if not the—fastest lava on Earth. A 1977 eruption of Nyiragongo created lava—an extremely low-viscosity mafic type—that traveled at an estimated 40 mph. The 2002 flow is thought to have been slightly slower.

11. BLUE LAVA ISN'T REAL …

Frequently making the rounds on social media are images of "blue lava" from the Indonesian volcano Kawah Ijen. Sadly, the amazing blue glow isn't actual lava. Instead it's caused by sulfuric gases that emerge at high temperatures and ignite, which then can flow down as a glowing liquid sulfur. Blue flames caused by ignited methane gas from burned plant matter are appearing in Hawaii as well.

12. … BUT BLACK LAVA IS.

The coolest (by temperature) lava in the world is at Ol Doinyo Lengai in Tanzania. Lava generally ranges from 1300°F–2300°F (700°C –1250°C), depending on its composition. But the lava at Ol Doinyo Lengai is only around 1000°F. It's also the world's only known active carbonatite volcano (a carbonatite is an igneous rock that's mostly carbonate minerals), which means instead of flowing red, the lava flows black and then solidifies white. The ultimate origin of the weird lava at Ol Doinyo Lengai is still a matter of debate, but because it's responsible for much of the world's rare-earth element production, it's increasingly being studied for economic reasons.

13. THERE'S A RESTAURANT THAT USES LAVA TO COOK FOOD.

If you find yourself wanting a unique experience on the island of Lanzarote in the Canary Islands, there's a restaurant called El Diablo. What makes it unique is that the grill is placed on top of a 6-foot deep hole with lava at the bottom (although it's considered safe as the last eruption was in 1824). Dining here might be a better choice than trying to roast marshmallows over a volcanic vent, which the USGS strongly advised people not do, noting that even if it weren't dangerous to be near a vent, the sulfur dioxide and hydrogen sulfide likely being emitted would make your marshmallow taste awful.

14. MARS MAY HAVE LAVA CHANNELS.

Whether the deep channels on the surface of Mars were caused by lava or water is hotly debated by researchers. It may seem like it would be easy to tell the difference, but in 2010, researchers analyzed a lava flow from 1859 in Hawaii and found features that looked very similar to channels on Mars that were thought to be carved by water. They concluded that fast and low-viscosity lavas could create many of these features that we thought were water-made. A 2017 study came to a similar conclusion on a different part of Mars, saying that what's traditionally seen as signs of rivers and lakes in one region "can be better explained by fluid lava flooding the channels and filling pre-existing impact craters."

15. CLEANING UP LAVA CAN TAKE MONTHS OR YEARS—IF IT HAPPENS AT ALL.

USGS via Getty Images

Returning a landscape to normalcy up after a volcano can be difficult. If a lot of ash has built up, proper care must be taken to dispose of the ash at a dedicated site all while avoiding inhaling glass, fine silica dust, and toxic gases into the lungs, which could lead to serious illness. Lava is even more difficult. According to Accuweather, contractors rarely fully remove the hardened lava, which can take months or years to completely cool. Even then, removing the lava—which is now rock—requires specialized tools. "In the Hawaii case, we are talking about lava that is incredibly sticky and viscous, and that is nearly 2000°F," University at Buffalo volcanologist Greg Valentine told Digital Trends. "No house can stand up to that, and even if it could, it would be partly or completely buried when everything is over." For these reasons, most people just start anew.

10 LEGO Sets For Every Type of LEGO Builder 

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If you’re looking for a timeless gift to give this holiday season, look no further than a LEGO set. With kits that cater to a wide age range—from toddlers fine-tuning their motor skills to adults looking for a more engaged way to relax—there’s a LEGO set out there for everyone. We’ve rounded up some of our favorite sets on Amazon to help you find the LEGO box that will make your loved one smile this year. If you end up getting one for yourself too, don’t worry: we won’t tell.

1. Classic Large Creative Gift Box; $44

Amazon

You can never go wrong with a classic. This 790-piece box contains dozens of types of colored bricks so builders of any age can let their inner architect shine. With toy windows, doors, tires, and tire rims included in addition to traditional bricks, the building possibilities are truly endless. The bricks are compatible with all LEGO construction sets, so builders have the option of creating their own world or building a new addition onto an existing set.

Buy it: Amazon

2. Harry Potter Hogwarts Express; $64

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Experience the magic of Hogwarts with this buildable Hogwarts Express box. The Prisoner Of Azkaban-inspired kit not only features Hogwarts's signature mode of transportation, but also Platform 9 ¾, a railway bridge, and some of your favorite Harry Potter characters. Once the train is built, the sides and roof can be removed for play within the cars. There is a Dementor on board … but after a few spells cast by Harry and Lupin, the only ride he’ll take is a trip to the naughty list.

Buy it: Amazon

3. Star Wars Battle of Hoth; $160

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Star Wars fans can go into battle—and rewrite the course of history—by recreating a terrifying AT-AT Walker from the Battle of Hoth. Complete with 1267 pieces to make this a fun challenge for ages 10 and up, the Walker has elements like spring-loaded shooters, a cockpit, and foldout panels to reveal its deadly inner workings. But never fear: Even though the situation might look dire, Luke Skywalker and his thermal detonator are ready to save the day.

Buy it: Amazon

4. Super Mario Adventures Starter Course; $60

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Kids can play Super Mario in 3D with LEGO’s interactive set. After constructing one of the courses, young designers can turn on the electronic Mario figurine to get started. Mario’s built-in color sensors and LCD screens allow him to express more than 100 different reactions as he travels through the course. He’ll encounter obstacles, collect coins, and avoid Goomba and Bowser to the sound of the Mario soundtrack (played via an included speaker). This is a great gift for encouraging problem-solving and creativity in addition to gaming smarts.

Buy it: Amazon

5. Gingerbread House; $212

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Gingerbread houses are a great way to enjoy the holidays … but this expert-level kit takes cookie construction to a whole new level. The outside of the LEGO house rotates around to show the interior of a sweet gingerbread family’s home. Although the living room is the standout with its brick light fireplace, the house also has a kitchen, bedroom, bathroom, and outdoor furniture. A LEGO Christmas tree and presents can be laid out as the holidays draw closer, making this a seasonal treat you can enjoy with your family every year.

Buy it: Amazon

6. Elsa and Olaf’s Tea Party; $18

Amazon

LEGO isn’t just for big kids. Toddlers and preschoolers can start their LEGO journey early by constructing an adorable tea party with their favorite Frozen characters. As they set up Elsa and Olaf’s ice seats, house, and tea fixings, they’ll work on fine-motor, visual-spatial, and emotional skills. Building the set from scratch will enable them to put their own creative spin on a favorite movie, and will prepare them for building more complicated sets as they get older.

Buy it: Amazon

7. Collectible Art Set Building Kits; $120

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Why buy art when you can build it yourself? LEGO’s Beatles and Warhol Marilyn Monroe sets contain four options for LEGO art that can be built and displayed inside your home. Each kit comes with a downloadable soundtrack you can listen to while you build, turning your art experience into a relaxing one. Once you’re finished building your creation it can be exhibited within a LEGO brick frame, with the option to hang it or dismantle it to start on a new piece. If the 1960s aren’t your thing, check out these Sith and Iron Man options.

Buy it: Amazon

8. NASA Apollo Saturn V; $120

Amazon

The sky (or just the contents of your LEGO box) is the limit with LEGO’s Saturn V expert-level kit. Designed for ages 14 and up, this to-scale rocket includes three removable rocket stages, along with a command and service module, Lunar Lander, and more. Once the rocket is complete, two small astronaut figurines can plant a tiny American flag to mark a successful launch. The rocket comes with three stands so it can be displayed after completion, as well as a booklet for learning more about the Apollo moon missions.

Buy it: Amazon

9. The White House; $100

Amazon

Reconstruct the First Family’s home (and one of America’s most famous landmarks) by erecting this display model of the White House. The model, which can be split into three distinct sections, features the Executive Residence, the West Wing, and the East Wing of the complex. Plant lovers can keep an eye out for the colorful rose garden and Jacqueline Kennedy Garden, which flank the Executive Residence. If you’re unable to visit the White House anytime soon, this model is the next best thing.

Buy it: Amazon

10. Volkswagen Camper Van; $120

Amazon

Road trip lovers and camping fanatics alike will love this vintage-inspired camper. Based on the iconic 1962 VW vehicle, LEGO’s camper gets every detail right, from the trademark safari windshield on the outside to the foldable furniture inside. Small details, like a “Make LEGO Models, Not War” LEGO T-shirt and a detailed engine add an authentic touch to the piece. Whether you’re into old car mechanics or simply want to take a trip back in time, this LEGO car will take you on a journey you won’t soon forget.

Buy it: Amazon

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Why Your Christmas Lights Always Get Tangled, According to Science

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iStock

A Christmas tree isn't a Christmas tree without those pretty colored lights, right? OK, no problem. You stored them in a box marked "Xmas lights" 11 months ago. You know where the box is. Now you just have to open the box, grab the lights, and—

That's where it gets tricky. Unless you're very lucky, or extremely well organized, the lights are likely all tangled up; soon you're down on your hands and knees, struggling to untangle a spaghetti-like jumble. (And it's not just you: A couple of years ago, the British grocery chain Tesco hired temporary "Christmas light untanglers" for the holiday season.) But why are Christmas lights so prone to tangling in the first place—and can anything be done about it?

Why do Christmas lights get tangled in the first place?

There are really two separate problems, explains Colin Adams, a mathematician at Williams College in Williamstown, Massachusetts, and the author of The Knot Book, an introduction to the mathematical theory of knots. First, the cord on which the lights are attached is prone to tangling—just as headphone and earbud cords are (or, in the past, telephone handset cords).

Several years ago, physicists Dorian Raymer and Douglas Smith, then at the University of California, San Diego, did a study to see just how easily cords can get tangled. They put bits of string of various lengths in a cube-shaped box, and then mechanically rotated the box so that the strings tumbled around, like socks in a dryer, repeating the experiment more than 3400 times. The first knots appeared within seconds. More than 120 different types of knots spontaneously formed during the experiment. They also found—perhaps not surprisingly—that the longer the string, the more likely it was to become knotted (few knots formed in strings shorter than 18 inches, they noted). As the length of the string increased, the probability of a knot forming approached 100 percent.

The material that the string (or cord) is made of is important too; a more flexible cord is more likely to tangle than a less flexible one. And while the length of the cord matters, so does its diameter: In general, long cords get tangled more easily than short ones, but a cord with a large diameter will be less flexible, which reduces the risk of knotting. In other words, it's the ratio of length to diameter that really matters. That's why a garden hose can get tangled—it's relatively stiff, but it's also very long compared to its diameter.

But that's not the end of the story. If a cord has a metal wire inside it—as traditional Christmas lights do—then it can acquire a sort of "natural curvature," Jay Miller, a senior research scientist at the Connecticut-based United Technologies Research Center, tells Mental Floss. That means that a wire that's been wrapped around a cylindrical spool, for example, will tend to retain that shape.

"Christmas lights are typically spooled for shipping or packing, which bends metal wire past its 'plastic limit,' giving it natural curvature approximately the size of the spool it was wound around," Miller says. Christmas lights can be even harder to straighten than other wound materials because they often contain a pair of intertwined wires, giving them an intrinsic twist.

And then there's the additional problem of the lights. "Christmas lights are doubly difficult, once things get tangled, because there are all of these little projections—the lights—sticking out of them," Adams says. "The lights get in the way of each other, and it makes it very difficult to pull one strand through another. That means once you're tangled, it's much harder to disentangle."

How do you fix tangled Christmas lights?

What, then, can be done? One option would be for manufacturers to make the cord out of a stiff yet elastic material—something that would more readily "bounce back" from the curvature that was imparted to it while in storage. A nickel-titanium alloy known as Nitinol might be a candidate, says Miller—but it's too expensive to be a practical choice. And anyway, the choice of material probably makes little difference as long as the lights still protrude from the cord. Perhaps the biggest breakthrough in recent years has been the proliferation of LED "rope lights" that don't employ traditional bulbs at all; rather, they use LEDs embedded within the rope-like cord itself. Of course, these can still get tangled up in the manner of a garden hose, but without those pesky protrusions, they're easier to untangle.

A simpler solution, says Adams, is to coil the lights very carefully when putting them away, ideally using something like twist-ties to keep them in place. (Martha Stewart has proposed something similar, using sheets of cardboard instead of twist-ties.)

Meanwhile, the mathematicians have some advice if you find yourself confronted with a hopelessly tangled, jumbled cord: Find one of the "free" ends, and work from there.

"Eventually," Adams assures us, "you will succeed."