The Caldera of Santorini is today a ring of islands in the Aegean. Photograph by Flickr member EmreKanik.

A caldera is a very large crater that forms after a very large volcanic eruption. The eruption is explosive and ejects a lot of material. Most of what comes out of the volcano is blown a great distance into the atmosphere and over a large area, so a huge volume of the local landscape is simply gone—thus the large crater.

Many people know about the Yellowstone Caldera because it is the location of a lot of interesting ongoing thermal and volcanic activity, some of which has been in the news lately, and it has even been featured in a recent epic disaster fiction film called 2012 in which the re-explosion of the Yellowstone Caldera is only one problem of many faced by the film’s heroes and heroines.

Somewhat less known but still famous is the Santorini Caldera. It is in the Aegean Sea, in Greece, near the island of Crete. Santorini blew about 1,600 B.C. and seems to have caused the end of the Minoan Civilization; the edge of the volcano’s caldera is now a ring of islands. By comparison with Yellowstone, Santorini is small. The Yellowstone Caldera is about 55 by 72 kilometers in size, while Santorini’s is about 7 by 12 kilometers.

Santorini is the subject of an investigation just reported in the journal Nature. The volcano has blown numerous times in the past. The investigation shows that the last explosion, the one at about 1,600 B.C., was preceded by a stunningly short period of build-up of underground magma. It seems as though the magma, enough for a very large eruption, moved into the zone beneath the caldera in two or more events less than 100 years prior to the explosion, with a significant amount of the magma moving into place just a few years before the blast.

If we go back a decade or so, volcanologists thought that the buildup to a major eruption like this would take more time, perhaps many centuries. Various lines of evidence have caused scientists to start to think that the buildup to blast-time might be shorter than that, and the present report is an excellent direct measurement of the timing which seems to confirm these growing suspicions.

How can scientists tell that it happened this way? Using volcano forensics, of course! Here’s the basic idea:

When shocking events happen, such as the intrusion of a bunch of magma into an area of rock, or associated seismic activities, the various chemicals in magma become “zoned.” Waves of energy passing through the molten rock cause bands of specific types of chemicals to form. During a period of no shocks, if the temperature is high enough, these bands dissipate. Some bands dissipate in very short periods of time, others over very long periods of time. If at any point the magma is released in a volcanic explosion such as the type that forms a caldera, the material suddenly cools and the state of the bands, dissipated to a certain degree, is preserved. Later, sometimes thousands of years later, geologists can study the rocks and estimate the amount of time between shock event and the volcanic explosion by measuring how much dissipation has occurred. It is a sort of magma-based clock.

In the case of Santorini, everything seems to have happened well within a century. This formation of a magma chamber large enough to cause a major eruption occurred after an 18,000-year-long dormant period. So, if we were thinking that the long period of time between caldera eruptions was characterized by a slow and steady buildup of magma, we were probably wrong. The real significance of this is that we can’t look at a caldera that is known to have erupted multiple times and rule out a future eruption simply on the basis of a low level of current activity. And of course, we are left wondering what initiates this rather rapid recharge of the magma underneath a caldera.

It’s a good thing that scientists are studying and monitoring these volcanoes!

Druitt, T., Costa, F., Deloule, E., Dungan, M., & Scaillet, B. (2012). Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano Nature, 482 (7383), 77-80 DOI: 10.1038/nature10706

The aurora borealis in northern Norway. Photo by AP Photo / Scanpix Norway, Rune Stoltz Bertinussen

Our photo gallery of the most stunning images from the recent northern lights show.

Precious few people around the world have ever had the chance to witness the remarkable phenomenon known as the aurora borealis, or northern lights. The collision of magnetically charged solar particles with the earth’s magnetosphere produces dancing waves of florescent green and deep blue that appear to wave across the sky, but under normal conditions, the lights can been seen only in far northern latitudes. Even then, the aurora borealis is unpredictable in occurrence and can be difficult to spot.

Recent storms on the surface of the sun, though, have produced levels of solar particles headed towards the earth not seen for a decade—and dazzling northern lights. Skygazers report that, over the past week, remarkably intense displays have appeared in skies in Scandinavia and Northern England. Scientists predict that recent surges are just a small taste of what’s to come over the next year or so, as the cycle of solar activity is expected to peak in 2013 and 2014.

Some scientists have suggested the weight of water in the lake created by the Zipingpu Dam in China triggered the 2008 Sichuan earthquake (courtesy of flickr user TaylorMiles)

On Saturday, a magnitude 4.0 earthquake shook eastern Ohio, a week after a smaller temblor in the region worried officials so badly that they halted work on a fluid-injection well in Youngstown.

This wasn’t the first case in which the injection of fluids into the earth has been linked with earthquakes. In April, for example, the English seaside resort town of Blackpool shook from a magnitude 2.3 earthquake, one of several quakes now known to have been caused by hydraulic fracturing (or “fracking,” which involves pumping large amounts of fluid into the ground to release natural gas) in the area. The link has been known for decades—a series of quakes in the Denver, Colorado, region in 1967 was caused by fluid injection.

The phenomenon is so well known that Arthur McGarr, a geologist at the U.S. Geological Survey in Menlo Park, California, has developed a method to predict the highest magnitude of an earthquake that could be produced by hydraulic fracturing, carbon sequestration, geothermal power generation or any method that involves injecting fluid deep into the earth. Though the method doesn’t allow scientists to predict the likelihood that such a quake would occur, it will let engineers better plan for worst-case scenarios, McGarr told Nature.

Hydraulic fracturing naturally causes small tremors, but bigger quakes may occur if the liquid migrates beyond the area where it’s injected. The New York Times reports:

The larger earthquakes near Blackpool were thought to be caused the same way that quakes could be set off from disposal wells—by migration of the fluid into rock formations below the shale. Seismologists say that these deeper, older rocks, collectively referred to as the “basement,” are littered with faults that, although under stress, have reached equilibrium over hundreds of millions of years.

“There are plenty of faults,” said Leonardo Seeber, a seismologist with the Lamont-Doherty Earth Observatory. “Conservatively, one should assume that no matter where you drill, the basement is going to have faults that could rupture.”

Earthquakes caused by fracking are of particular interest right now because the number of wells, particularly in the United States, has been skyrocketing (along with reports of nasty environmental consequences, such as flammable water). But this is only one way that humans are causing the earth to quake. Mining (taking weight from the earth), creating lakes with dams (adding weight on top of the earth) and extracting oil and gas from the earth have caused at least 200 earthquakes in the last 160 years, Columbia University earthquake scientist Christian Klose told Popular Science.

Klose’s research has demonstrated that coal mining was responsible for Australia’s most damaging earthquake in recent memory, the magnitude 5.6 Newcastle earthquake of 1989. And in 2009, he was one of several scientists who suggested that the magnitude 7.9 earthquake in China’s Sichuan Province in 2008, which left 80,000 dead, could have have been triggered by the Zipingpu Dam. (That wasn’t the first time a dam was linked to an earthquake—Hoover Dam shook frequently as Lake Mead filled.)

It can be easy to look at our planet and think we’re too small to really do much damage, but the damage we can do can have severe consequences for ourselves. ”In the past, people never thought that human activity could have such a big impact,” Klose told Wired, “but it can.”

Ecologists warn that New England's maples could be at risk (courtesy of flickr user paul+photos=moody)

The blog io9 is running a series of Public Science Triumphs, explaining how publicly funded science makes the world a better place. “It’s tempting to offload the cost of science onto business, but there are some kinds of research that only government can make possible,” io9 editor Annalee Newitz wrote this weekend in the Washington Post. That research, often called “basic,” may seem useless to some but can lead to great payoffs in the future. Basic research provides the foundation for monumental discoveries, fosters the development of ground-breaking technologies and gives us the information we rely on when making important decisions, like when and where to build and how strong to make a structure.

An important, and often under-appreciated, source of that information comes from the world of ecology. Everything in the world is connected, but not in the new age way most people mean when they say that. It’s all connected through more mundane (though, frankly, more fascinating) ways, like carbon and nitrogen cycles, food webs, water and fire—the subjects of the science of ecology. And it’s this kind of information that will help a builder to know why a warehouse will flood even if constructed a fair distance from the river, explain how reintroducing wolves to Yellowstone led to an increase in beaver dams and guide management decisions, such as setting levels for sustainable fishing of salmon.

Ecology is not a glamorous science; no one will ever accuse an ecologist of being motivated by money. (The practical clothes and sensible sandals usually deter such accusations.) Field sites are basic, at best. Your average college dorm provides more space and better food. But an ecologist probably won’t mind because she’s happier out in the muck anyway.

Much ecological research provides a simple slice in time, perhaps a few years of data. But to truly understand how everything is working together, more data is needed. That’s where the Long Term Ecological Research (LTER) Network comes in. These are sites all over the world (included 26 in the U.S. LTER Network, funded by the National Science Foundation) that have been collecting data on primary production (the energy created by plants), the distribution of organisms in the ecosystem, the decay of dead organisms, the movement of water and nutrients, and the patterns of disturbances—at some sites for more than 30 years. Put that data together and an ecologist will have a picture of how organisms and the world around them are working together, and affecting the human population, too.

At Harvard Forest, for example, LTER ecologists have documented the spread of the Asian long-horned beetle (ALB), which took up residence in Worcester, Massachusetts a decade ago. Scientists have been trying to keep the beetle confined to the city, but LTER scientists found that the insect has spread to the nearby forest, infesting nearly two-thirds of the maple trees in one area. “If the ALB continues to spread outside Worcester, the abundance of red maples could provide a pathway for its dispersal throughout New England and other parts of eastern North America,” says the study‘s co-author, David Orwig of Harvard University. And if the beetles spread and take out New England’s maples, they would also destroy the region’s maple industry and even, perhaps, a good portion of the autumn tourist trade. More than one million people come to the area each year, spending about $1 billion in their quest to see the red maples’ stunning foliage. Knowing the maples are at risk may lead to changes in how the infestation is being fought.

Ecology, and especially long-term ecological projects, are scientists’ “gifts to the future,” as one of my colleagues put it. There is no Nobel Prize for ecology, and groundbreaking research papers are rare. Ecologists are pursuing this science because they simply want to know. And the benefits for the rest of us can be monumental. By better understanding how an ecosystem works, we are able to make better decisions that can save money and prevent disasters. No company is ever going to pay for this–their shareholders would never stand for it–but I’m glad to see NSF and other government agencies step in.

A false-color image of flooding in Bangkok, Thailand (Image Credit: NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team)

If you think we’ve been having a wild weather year here in the United States (with droughts, horrible tornadoes, a freakishly early northeast snowstorm, to mention a few events), be glad you’re not in Thailand. From NASA:

Since July 2011, heavy monsoon rains in southeast Asia have resulted in catastrophic flooding. In Thailand, about one third of all provinces are affected. On Oct. 23, 2011, when this image [above] from ASTER, the Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument on NASA’s Terra spacecraft was acquired, flood waters were approaching the capital city of Bangkok as the Ayutthaya River overflowed its banks. In this image, vegetation is displayed in red, and flooded areas are black and dark blue. Brighter blue shows sediment-laden water, and gray areas are houses, buildings and roads.

And if it wasn’t bad enough to have your home flooded, have to search for food and clean water along with other drenched city dwellers and have the threat of illnesses like cholera hanging over your head, Bangkok’s residents also have to avoid the crocodiles let loose from flooded crocodile farms.

Meanwhile, scientists are warning that climate change will bring even weirder and worse weather events in the future. “The extremes are a really noticeable aspect of climate change,” Jerry Meehl, senior scientist at the National Center for Atmospheric Research, told the Guardian. “I think people realize that the extremes are where we are going to see a lot of the impacts of climate change.”

Check out the entire collection of Surprising Science’s Pictures of the Week and get more science news from Smithsonian on our Facebook page.

The Terkezi Oasis in Chad, as seen from Landsat 7 (Credit: USGS)

When someone at the USGS Earth Resources Observation and Science Center saw this image of the Terkezi Oasis in Chad, taken by the Landsat 7 satellite, he or she saw art and included it in the Earth as Art collection. But when I came upon it, and mentally rotated it by 90 degrees (as shown above), I saw a ghostly screamer with one arm raised in anger.

Admittedly, I had primed my brain for such a discovery, searching for Halloween-ish images in keeping with the season, but I probably would have seen a face even if I hadn’t been thinking of monsters and ghosts. We often find patterns in places where they don’t exist, whether it be a witch’s head in a nebula, initials in the echoes of the Big Bang or the Virgin Mary in a piece of toast.

There are definite advantages in being able to recognize patterns—when they are real, they can provide useful information about the world around us, information that can help us to prosper and stay alive. But we haven’t necessarily evolved to tell real patterns apart from false ones, as Michael Shermer pointed out in Scientific American a few years ago:

Unfortunately, we did not evolve a Baloney Detection Network in the brain to distinguish between true and false patterns. We have no error-detection governor to modulate the pattern-recognition engine. (Thus the need for science with its self-correcting mechanisms of replication and peer review.) But such erroneous cognition is not likely to remove us from the gene pool and would therefore not have been selected against by evolution.

Shermer points to a study in Proceedings of the Royal Society B that examined the phenomenon and demonstrated that whenever the cost of believing in a false pattern (e.g., ghosts are real) is less than the cost of not believing in a real pattern (e.g., snakes of a specific color can kill), then natural selection will favor the belief in patterns, whether real or not. “Such patternicities, then, mean that people believe weird things because of our evolved need to believe nonweird things,” Shermer writes.

So if you believe in ghosts or witches or other things that go bump in the night, I guess you can blame evolution.

A storm rolls in above Bangkok (courtesy of flickr user Dennis Wong)

I’m kind of obsessed with weather. There’s a practical side to this—I don’t own a car and getting caught in a rain or snow storm can be a problem—but I also a have quite a bit of awe for the power of nature. I once lived on the edge of Tornado Alley, and I’ve experienced ice storms, torrential downpours, high winds, blizzards and hurricanes. I always keep an eye on the weather and have a plan when something bad is predicted or formulate a plan when something bad starts to happen. But I’m realizing that I may be in the minority.

Back in January, a huge ice storm headed towards Washington, D.C. A local weather blog recommended people be off the streets by 4 p.m., but few heeded the warning. They headed out as the ice started to fall and it took some people eight hours or more to get home. If they made it at all.

When a hurricane heads towards land, some people call the local television station to ask if they should be boarding up their houses. And they get angry when the forecast turns out to be wrong, which can easily happen even with all of our modern prediction tools. That is understandable when a storm turns out to be worse than expected, but it can also be dangerous when it goes the other way. How many people who evacuated from New York City prior to Hurricane Irene, which didn’t bring as much flooding to the area as had been predicted, will heed future warnings?

The death toll from the May tornado in Joplin, Missouri was so high, in part, because people didn’t heed the warnings. There had been so many false alarms in the past that they didn’t think it necessary to take shelter.

In August, five people died and dozens were injured when an outdoor stage collapsed at the Indiana State Fair due to high winds. The sky had turned black as a storm rolled in and but few people left.

We have more weather information than at any time in our past. NOAA’s predictions of the paths of hurricanes get better and better. We get warnings that a tornado is headed our way with plenty of time to take shelter. We can learn to make our own predictions from the plethora of raw data available online and even have instant access to weather information on our computers and smartphones.

But that hasn’t made us immune to the dangerous and costly effects of weather. A study earlier this year [PDF] estimated the cost of weather in the United States may be as high as $485 billion a year. “It’s clear that our economy isn’t weatherproof,” says NCAR scientist Jeffrey Lazo, the study’s lead author. “Even routine changes in the weather can add up to substantial impacts on the U.S. economy.”

I don’t mean to imply that all those costs are avoidable, but surely there’s room for improvement, especially when it comes to personal safety. I worry that many people have become so dependent on technology and the forecasts and advice from others (whether professional meteorologists or friends and family) that we don’t look at the skies anymore. The wind kicks up, the skies turn black, and we don’t do anything. We don’t take shelter. We don’t change our schedules. We don’t slow our cars. And it’s no wonder when bad things happen.

What’s to be done? Well, take the time to educate yourself about the warning signs of severe weather. Learn about hurricanes, tornadoes, floods or any other type of weather event that may strike your area before the threat becomes real. Heed the warnings of professionals, even if they later turn out to be false. Take shelter when the weather takes a turn for the worse. Go home early, before a storm begins. And err on the side of caution. Because it’s better to waste a little time and money than end up dead.

Irene created a new channel across a North Carolina barrier island (courtesy of flickr user NCDOTcommunications)

When I first learned about barrier islands, back in high school, I couldn’t believe that people would live on one. That’s because barrier islands aren’t permanent; they’re just accumulations of sand that form off the coast (many can be found on the U.S. East Coast). And it’s a natural state for these islands to grow and erode and get washed away. A strong enough storm can cut an island in half, as seen after Irene in the photo above, or take away the wide swath of beach that had been between homes and the ocean. What had been prime beachfront property one day can be open ocean the next.

And people can compound the problem. The point of buying beachfront property is to get a great view of the ocean, but destroying the sand dune to get closer to the beach eliminates the feature that protects the beach from erosion. In addition, building jetties and adding sand in attempts to keep an island stable can hasten erosion elsewhere. Building on a barrier island can also limit the island’s usefulness in protecting the mainland coast from powerful storms as well as eliminate important ecosystems, such as dunes and salt marshes.

The best way to limit development on these fragile islands is probably not to outlaw it, though. There’s so much development already on these islands that there’s no possibility of clearing it all away and letting nature take over. But we could add more of these islands to the Coastal Barrier Resources System. People are not prohibited from developing land in this system. Instead, the act that created the system “limits the Federal financial assistance for development related activities such as spending for roads, wastewater systems, potable water supply, and disaster relief,” NOAA explains. In other words, you can build here, but you’re not getting any help from the feds.

As a result of this program, NOAA estimates that U.S. taxpayers saved $1.3 billion between 1982 and 2010. People do build on CBRS land, but it’s more expensive to do so without federal assistance, so less development occurs. And because the land is less developed, these ecosystems often stay intact, providing homes for migratory birds, rare plants and animals. The land is also allowed to grow and erode naturally and serve as the barrier it is meant to be.

One of the most dangerous jobs in science has to be a volcanologist. When you watch the video above you can see why (although trying to get that close to a bubbling cauldron of lava is not just dangerous; it’s stupid enough that even your fellow volcanologists will yell at you). But collecting and analyzing samples of lava and deadly gases are just a couple tools in the volcanologist’s box; here are some of the other—safer—ways they study volcanoes:

Measure seismic activity: Earthquakes are an early warning sign that something is going on underground with a volcano. The rumblings can be difficult to interpret, but an increase in activity often presages an eruption.

Measure ground movements: Scientists often set up sensitive tiltmeters that can detect the tiniest changes in the shape of a volcano’s surface. Before an eruption, the volcano may start to bulge as magma accumulates closer to the surface. Before Mount St. Helens erupted in 1980, the north side of the volcano visible bulged, but more often this deformation is detectable only with sophisticated equipment.

Take the volcano’s temperature: If a volcanologist wants to see how hot a volcano has become and which lava flows are newer (and hotter), there’s no need to get up close. A thermal imaging camera on an airplane or satellite can take a picture and identify the hot spots.

Check on its geophysical properties: Minute changes in the electrical conductivity, magnetic field and even gravity around a volcano can indicate that something is brewing beneath the surface.

Map it in three dimensions: A 3-D map of all the nooks and crannies on the surface of a volcano can help scientists make predictions about where the lava will flow and who is most in danger in the event of an eruption.

Study the volcano’s past: Scientists examine geologic deposits to learn about past eruptions, which can give important clues to what a volcano may do in the future.

(HT: Bad Astronomy)

A hexagonal grain of iron sulfide in a diamond may be a flaw for jewelers, but it's useful data for scientists (Credit: Jeffrey Harris, University of Glasgow)

When it comes to diamonds in jewelry, perfection is everything. But tiny little inclusions–imperfections in the crystal structure–are a clue to the past. In a study published last week in Science, scientists have now analyzed more than 4,000 inclusions found in diamonds to determine just when plate tectonics began.

As you probably know, the Earth is covered with tectonic plates that grow and move and dive under and crash into each other, creating and destroying continents and oceans over billions of years. Scientists call this the Wilson Cycle, but just when it began has been a mystery.

Diamonds are created in the Earth’s mantle, the hot and viscous layer between the core and the crust. Volcanic eruptions then bring them to the surface. There are two types of inclusion in diamonds: Peridotitic inclusions come from the melting of the mantle, which has happened continuously through Earth’s history. Eclogitic inclusions derive from shallow, partial melting that most often occurs during the formation of oceanic crust.

The scientists used two types of isotopic dating to determine when each of the diamonds in the study formed. They found that diamonds with peridotitic inclusions formed before 3.2 billion years ago, and after 3 billion years ago, eclogitic inclusions were far more common. The researchers concluded that the cycle of plate tectonics must have started around 3 billion years ago.

“The simplest explanation” for the emergence of eclogitic inclusions as the dominant type, says the study’s lead author, Steven Shirey of the Carnegie Institution of Washington, is that this change came from the initial subduction of one tectonic plate under the deep mantle keel of another as continents began to collide on a scale similar to that of the supercontinent cycle today.”

Eyjafjallajökull, courtesy of Flickr user anjci

Dangers come in so many forms, and it’s tough to compare countries by overall risk. China and Haiti have suffered devastating earthquakes; Indonesia and Japan have been inundated by tsunamis; Sierra Leone has the highest rate of malaria deaths; and mudslides, tornadoes, hurricanes and floods strike many parts of the world. But for sheer variety and drama of natural disasters, it’s hard to top Iceland.

Iceland is pretty much the least habitable of all the places that people have inhabited. But it’s a great place to visit, and I just returned from a vacation there. (I apologize for the periods of radio silence on Surprising Science over the past two weeks, by the way; Sarah was sick and I was out of town. She’s on the mend and will be back soon.) Iceland was the most spectacular place I’ve ever seen—I felt like I was like hiking through a geology textbook. It has glaciers, volcanoes, fjords, geysers, mud pots, lava fields, lava tubes, flood plains and waterfalls. Most spectacularly, it’s one of the only places where you can walk along the mid-Atlantic rift, the seam where the European and North American plates are separating (the rest of the rift is under the Atlantic Ocean).

But geologic activity has consequences. Iceland’s volcanoes are its most famous natural threat—Eyjafjallajökull erupted last summer and shut down air traffic over most of Europe for about a week. The Laki eruption in 1783 killed one-fifth of Iceland’s population and thousands more in other parts of Europe. The eruption of Hekla in 1104 covered half of the island with fallout and gave the mountain the reputation as the gateway to hell. In 1963, an offshore volcano created a new island, Surtsey. In 1973, firefighters pumped water onto a lava flow to save the harbor on the island of Heimaey.

Not all volcanoes spew ash and lava directly into the air or land. Some are covered with glaciers… which only compounds the problem. Icelandic has a word, “jökulhlaups” to describe a catastrophic flood caused by a volcano melting a glacier or ice cap from beneath. Iceland’s southern coast is one wide flood plain of debris washed away by jökulhlaups.

The earthquakes generally aren’t as strong as those along other fault zones, but they’re frequent, shallow and damaging. A quake in 1974 dropped a chunk of land six feet down; it filled with water, turned into a lake and flooded a farm. Another earthquake cracked the bottom of a lakebed and drained the water away.

Lava regularly erupts from volcanoes and fissures, burying towns and farms. You can hike along a 1984 lava field, practically still steaming, and plenty of craters (also named for hell) at Krafla. Shifting glacial runoff buried farms at Skaftafell, now the site of a fantastic national park. During the little Ice Age, glaciers devoured entire towns; today towns are more likely to be swept away by avalanches or covered in volcanic ash.

I really hated to leave the place, especially because it looks like Hekla is starting to rumble….

Still from Cars 2. Courtesy of Disney.

“They’re not only racing across the world—they’re racing to save the world,” declares the trailer of the new movie Cars 2. The animated feature is the latest kids’ movie with an environmental twist: Alternative-fuel-advocating heroes will show down with big-oil villains as the movie hits theaters today. We rounded up the top ten kids’ movies aimed at spreading the word about saving the environment.

1) FernGully: The Last Rainforest — This 1992 animated film depicts a magical rainforest inhabited by fairies but threatened by destructive loggers. When the loggers cut down a tree and release the evil spirit Hexxus, Crysta, the fairy protagonist, and her friends (including lumberjack Zak, whom Crysta shrunk down to miniature size to save his life) must find a way to defeat the pollution-loving demon and save their home. The movie’s message is overtly conservationist, villainizing destructive humans and urging viewers to do what they can to preserve the wilderness areas still left on Earth.

2) WALL-E — This hit film from 2008 takes place 700 years in the future, when the Earth has been reduced to a deserted, trash-covered ghost town. Robot WALL-E seems to be the last sentient being on the planet, as all the humans have fled to gigantic space ships that hover in outer space. One day, one of those ships comes to Earth, bringing advanced robot EVE, with whom WALL-E falls in love. He follows her back to space, and his adventures there eventually convince the humans they must return to Earth. The state of the Earth in the movie urges viewers to take notice of how their actions are affecting the environment and warns of what might happen if they don’t.

3) Bambi — The classic animated film from 1942 tells the story of a young deer and his friends who live in a forest threatened by hunters. When Bambi is still a fawn, his mother is killed by one of those hunters, and he must grow up without her. Bambi and his friends get older and he falls in love with another deer, Faline. Everything is peachy until the next day, when the forest goes up in flames and Faline is attacked by hunting dogs. Bambi is able to save her, and the couple eventually escapes to an island in a lake, where they live (at least we expect) happily ever after. The scene where Bambi’s mom dies would make even the most hardened hunter think about setting down his gun.

4) Over the Hedge When the forest animals, the main characters in Over the Hedge (2006), wake up from hibernation, they realize that half of their forest has been destroyed and replaced by a suburban neighborhood hidden behind a giant hedge. The animals, especially raccoon RJ, who is paying off a debt to an angry black bear, try to survive by stealing food from the humans who live on the other side of the hedge. The plot revolves more around the interactions among the animals than an environmental message, but some pointed comments are unmistakably meaningful: “That is an SUV,” says RJ in the trailer. “It’s so big!” respond the animals. “How many humans fit in there?” RJ’s reply is priceless: “Usually…one.”

5) Hoot — Based on a Carl Hiaasen novel, this 2006 film portrays the adventure of three middle-school students who try to protect a rare breed of endangered owls. The main character, Roy, just moved to Florida from Montana, and quickly makes friends with Beatrice and her truant stepbrother, “Mullet Fingers.” The three set out to derail a greedy CEO in his construction of a pancake restaurant on the vacant lot where the rare owls live. Not exactly an award-wining movie, but definitely one that encourages kids to think about the relationship between humans, development and wildlife.

6) Star Trek IV: The Voyage Home — Whether this 1986 film can be considered a movie for kids is debatable, but its environmental undertones are clear. It’s the year 2286, and a strange probe is approaching Earth, sending out signals that Spock determines match the calls of the extinct humpback whale. The probe is wreaking havoc on Earth, so the crew of the USS Enterprise decides to go back in time to 1986, where they find two whales in a San Francisco aquarium. A curator there explains to the crew members why the whales are endangered. They take the whales back to the future with them and release them in the San Francisco Bay, where the giant mammals answer the probe’s signal and stop the destruction. Logical? Maybe not. But with an environmental message? Most definitely.

7) Free Willy — Another movie with whales and an environmental message, Free Willy was a hit in 1993. It features a young boy who befriends a recently captured orca whale in a local aquarium/amusement park. The boy, Jesse, and the whale, Willy, bond, but Willy is in danger because he doesn’t perform tricks well and therefore doesn’t earn much money for the park. The park owner and his cronies threaten to kill Willy, so Jesse decides to release the whale into the wild. There’s no mistaking the villains in this movie—the park owner, who exploits animals, and the whalers who capture Willy—or the message that wild animals are better off left alone.

8) Disneynature’s Oceans — Though a bit more subtle than some of the other films on this list, Oceans still makes an impact. A documentary released on Earth Day in 2010, the film explores the underwater world that covers three-quarters of our planet. While it spends much of its time depicting the weird, wonderful and beautiful life forms that the oceans have to offer, the documentary doesn’t miss its chance to show the negative effects human actions can have on wildlife and urge viewers to respect nature.

9) Avatar – Again, it’s debatable whether this is a kids’ movie, but it’s clearly a film with environmental themes. A paraplegic soldier travels to the planet of Pandora, where he, in the form of his avatar, integrates with the indigenous Na’vi people. He is supposed to help conquer the foreign land, but soon finds himself siding with the Na’vi. There are many themes in this 2009 film, but among them are a respect for the environment (demonstrated by the graceful Na’vi), our ultimate reliance on nature and the destructive nature of humans and how it affects the planet.

10) Happy Feet — The main message of this 2006 Disney movie is that it’s okay to be different, but environmental themes work their way in as well. The film focuses on a young penguin, Mumble, with a talent for tap dancing—something none of the other penguins can do. It follows his adventures and quest for acceptance throughout the plot, but the environmental aspect shows up when Mumble is blamed for the scarcity of fish in the ocean, a nod to overfishing. In addition, one of Mumble’s friends wears a set of plastic six-pack rings around his neck like jewelry, only to later be choked by the piece of trash. Happy Feet is an example of the environment showing up in movies that are not directly about the environment.

Giving films a green theme is clearly a trend in cinema lately. What other environment-focused kids’ movies did we miss?

An icy landscape in northern Canada almost looks like water, as seen from the International Space Station (credit: ESA/NASA)

We live in an age of satellites; the skies above are full of them, usually just beyond our sight. And while we benefit plenty from the information they provide and the technologies they make possible, my favorite satellite product has to be the imagery. Many people marvel at the Hubble pictures of deep space, but my preference is for the images of Earth and especially the ones in which our planet turns into an Impressionist’s dream.

For years, the USGS has collected many of its Landsat images into “Earth as Art” collections, and now many of them are being displayed in an exhibit at the Library of Congress; you can see some here on Smithsonian.com.

But now I (and tens of thousands of others) are enjoying another collection: the European Space Agency’s Flickr stream. I’ve highlighted eight of my favorites from the Earth from Space category in this gallery. Which ones would you consider hanging as art in your home?

A model of estimated fault slip for the March 2011 Japanese earthquake. (Credit: Mark Simons/Caltech Seismological Laboratory )

Scientists knew something was wrong with their understanding of the offshore fault that was the source of the March 11 earthquake in Japan almost immediately after the shaking began. That part of the ocean floor, where the ocean plate subducts beneath Japan, was supposed to be simple and uniform, sometimes sticking and building up stress that should have released in segments, creating large (magnitude 7 or 8 ) earthquakes every few decades or centuries or so. A magnitude 9 quake was not possible, so they thought.

In the months that have followed, geophysicists have been looking into exactly what happened—aided by what might be the best earthquake sensor network on the planet, with hundreds of GPS data recorders documenting movements on land and the sea floor, along with other sensors that measured wave heights from the tsunami. And now some of these researchers have published early results (which are freely available online from the journal Science) from what one scientist called “the best recorded earthquake ever.” Here are a few of the highlights:

1 ) The geologic fault where the Japanese earthquake originated is far more complex than scientists once thought. Geophysicists suspect that a bit of the plate that is sinking beneath Japan, perhaps a seamount, had stuck—for reasons still unknown—causing strain to slowly build up over hundreds of years. Some researchers had previously assumed that the area had been slowly slipping without causing any quakes, but that was not correct.

2 ) About 250 kilometers of fault experienced significant slip during the event, about half the length of what would be expected in an earthquake of this magnitude. And the the most slip—30 meters or more—occurred in an even smaller area, only 50 to 100 kilometers long. Nothing like that had ever been recorded before. These realizations call into question previous conclusions that the fault nearer Tokyo could not create a similarly sized earthquake. “It is important to note that we are not predicting an earthquake [for the fault closer to Tokyo],” says Caltech geophysicist Mark Simons. “However, we do not have data on the area, and therefore should focus attention there, given its proximity to Tokyo.”

3 ) Different parts of the fault produced high- and low-frequency waves. High-frequency waves, which are generated by areas under the highest levels of stress, came from the edges of the area of slip, not where the fault began its break as seismologists had previously assumed. If the fault were compared with a piece of paper being torn in half, “the highest amounts of stress aren’t found where the paper has just ripped, but rather right where the paper has not yet been torn,” Simons says.

It’s somewhat heartening to realize that out of the death and destruction of the quake and tsunami is coming even better earthquake knowledge that will help us better prepare for—and perhaps one day even predict—earthquakes. For almost all of humankind’s existence, all we’ve been able to do in the face of earthquakes, tsunamis and other natural events is to clean up whatever is left after the disaster has hit. But science has changed much of that, and now we can plan and prepare for the inevitable and often stave off the worst possible outcomes.

Memphis, Tennessee on May 10, 2011 (Credit: NASA Earth Observatory/United States Geological Survey)

Memphis, Tennessee on April 21, 2011 (Credit: NASA Earth Observatory/United States Geological Survey)

The Mississippi River doesn’t like to stay where it is, but then most rivers prefer to meander, expanding beyond their banks on occasion, at other times forging new paths across the landscape. This isn’t a problem unless you’ve built cities and towns and farms up and down its banks, as we’ve done. And so flooding happens, despite our best efforts to control the waters and keep our rivers safe and predictable.

The current Mississippi River floods are slowly working their way south (that’s Memphis in the Landsat photos, on May 10 (top) and April 21; waters reached nearly 48 feet), and already more than 3 million acres of land have been put underwater and thousands of people have been driven from home. Those waters are expected to crest in the coming days in Louisiana where the state has a rather nasty choice to make—open up the Morganza Spillway north of Baton Rouge, thereby flooding farms for 200 miles, or try to sandbag a similar distance in levees and hope that they’re not overtopped. If the levees don’t hold, New Orleans will be drowned in more water than the city saw during Hurricane Katrina.

If the water were diverted, it would go down a Mississippi River distributary, the Atchafalaya River, which is the shorter route to the ocean and the route that the river may prefer now. The Mississippi has not always drained into the Gulf of Mexico at its current location; that point has been as far west as Texas and as far east as the Florida panhandle in the geologic past. Scientists in the 1950s predicted that the river would soon divert its course and flow out to the Gulf through the Atchafalaya, which would render the New Orleans port unusable and set Morgan City to the west under water. In the 1960s, the Army Corps of Engineers set up the system of flood controls that exists today, splitting up the Mississippi’s water so that only 30 percent flows down the Atchafalaya and preserving the status quo. But it’s unclear if that system will survive this latest round of flooding (Salon has a nice write-up on this subject).

Which brings me to something I’ve been musing all day: If the Mississippi drains through the Atchafalaya, would our most-famous river take on that name? Or would the Atchafalaya cease to exist? I know, it’s a small matter, but I’d rather think on that than on death and destruction.

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