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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.

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.”

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