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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.

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.”

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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.