In the aftermath of Haiti’s devastating earthquake, nervous citizens can be forgiven for wondering where the next Big One will hit. Major quakes strike with alarming regularity: Earthquakes of magnitude 7 or greater occur approximately 18 times a year worldwide. They usually originate near faults where tectonic plates —tremendous fragments of the earth’s crust—collide or push above or below each other.
Geologists suspect that Haiti’s destructive quake resulted from 250 years of seismic stress that has been building up between the North American and Caribbean tectonic plates. In fact, a group of U.S. geologists presented a study in the Dominican Republic (which shares the island of Hispaniola with Haiti) in 2008 saying that the region was at risk of an earthquake potentially even bigger than last week’s magnitude 7.0 quake. Part of their presentation is particularly chilling in light of what would happen less than two years later: “This means that the level of built-up stress and energy in the earth could one day be released resulting in an earthquake measuring 7.2 or more on the Richter Scale. This would be an event of catastrophic proportions in a city [Port-au-Prince] with loose building codes, and an abundance of shanty-towns built in ravines and other undesirable locations.”
Earthquakes are still impossible to predict with precision; in the words of one of the geologists who predicted the Haiti quake, “It could have been the next day, it could have been 10 years, it could have been 100… This is not an exact science.” But researchers have identified a handful of seismic zones around the globe that are storing up especial amounts of stress and are particularly hazardous. Browse through the gallery for a world tour of the planet’s most seismically vulnerable regions.
By Aline Reynolds
Image: USGS
Groundwater levels around the country have been sinking as wells for drinking water and irrigation pull water out of aquifers faster than they can naturally recharge. Now, using gravity-measuring satellites, NASA and California researchers have documented the extent of water loss in California’s Central Valley, and the results aren’t good.
The measurements show the amount of water lost in the two main Central Valley river basins within the past six years could almost fill the nation’s largest reservoir, Lake Mead in Nevada [AP]. The total is about 30 cubic kilometer; one cubic km contains more than 264 billion gallons of water.
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Twitter: Bane of employers … but friend of science?
At a scientific meet-up in California this week, researchers with the U.S. Geological Survey proposed that the 140-character micro-blogging site could help to speed up responses to earthquakes. “Why would such a system work?” asked Paul Earle, a geologist at the USGS, at the American Geophysical Union fall meeting Monday. “Because people like to tweet after an earthquake” [Wired.com].
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For a geologist, “fast” still means thousands and thousands of years. But in a new study in Nature scientists argue that the modern Mediterranean Sea filled with water in a geologic blink of an eye. A torrential flood of water that moved 1,000 times faster than the Amazon River replenished the once-dry sea in perhaps just a few months, the researchers say.
History shows that the Strait of Gibraltar has often determined access to (and thus control of) the Mediterranean, and that goes for the water itself, too. Around 5.6 million years ago the Mediterranean Sea almost completely evaporated when it became disconnected from the Atlantic Ocean. This was due to uplift of the Strait of Gibraltar by tectonic activity, combined with a drop in sea level [New Scientist]. When the strait sank just enough to reach the water level 5.3 million years ago, ocean waters began to cascade through and fill the sea.
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In a bit of unexpected climate related good news—not for us, of course—some shell-building ocean dwellers like blue crabs, shrimp, and lobsters may actually benefit from increased ocean acidification. This surprising finding seems to be good news for lobster lovers, but researchers note that the ongoing acidification still appears to spell trouble for many marine creatures.
Scientists now think that acidifying oceans may allow these select crustaceans to build stronger shells and exoskeletons, instead of making them more brittle. Carbon dioxide (CO2)—the notorious byproduct of fossil fuel burning—dissolves in the ocean. That makes the ocean more acidic. It also reduces the number of so-called carbonate ions in seawater, and these ions are among the primary materials that sea creatures use to build their calcium carbonate shells and skeletons [LiveScience]. Justin Ries, a coauthor on the new study, speculates that these bottom dwellers are somehow better able to manipulate CO2 ions to build their shells, even though fewer CO2 ions are available to them in an acidic environment. However, exactly how they accomplish this is unknown.
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A super-colossal volcanic eruption rocked Italy 39,000 years ago, and troubling signs at the site, now known as Campi Flegrei, have many scientists wondering when the next big one will hit. To probe the issue, so to speak, the Campi Flegrei Deep Drilling Project will drill nearly 2.5 miles down into the collapsed volcanic crater to find out if another blast is on the horizon. Though the researchers on this particular project point out that any risk is small, it will begin amid debate about whether such endeavours are safe, given the unknowns of a volcano’s interior. A few say drilling might even trigger a major eruption [New Scientist]. However, scientists on the project say this isn’t likely, as their drills won’t dig deep enough to set off an eruption.
Campi Flegrei isn’t well known because it lacks a volcanic cone, but it dwarfs Mount Vesuvius. All of Naples sits within its caldera, an eight-mile-wide collapsed area of land formed by the eruption 39,000 years ago. A similar volcanic eruption would leave large parts of Europe buried under ash, say scientists, however smaller eruptions occur every few centuries; the last eruption was in 1538. The researchers hope that by drilling into the volcano, they’ll learn if another smaller eruption is imminent. They hope to locate fracture zones and magma pools that could only be guessed at without drilling. This could show exactly where magma might ascend and collect prior to an eruption. Meanwhile, rock samples could be tested under high stresses in the lab to help model the ground deformation prior to eruption [New Scientist]. The caldera’s center has risen about 10 feet since the 1960s, which has lit a fire under the researchers since a similar rise proceeded a series of intense eruptions 4,000 years ago.
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In 2005, the earth cracked open in Ethiopia. Two volcanic eruptions shook the desert, and a 35-mile-long rift opened in the land, measuring 20 feet wide in some places. Now a new study adds weight to the argument that the opening of this crack marks the first step in the formation of a new sea that may eventually separate East Africa from the rest of the continent. Says lead researcher Atalay Ayele: “The ocean’s formation is happening slowly, likely to take a few million years. It will stretch from the Afar depression (straddling Ethiopia, Eritrea and Djibouti) down to Mozambique” [ABC News].
The study, to be published in the journal Geophysical Research Letters, explains that the seismic movements observed in Ethiopia are very similar to the changes wrought by faults and fissures on the seafloor, where the processes that move tectonic plates usually begin.
Seismic data from 2005 shows that the rift opened in a matter of days. Dabbahu, a volcano at the northern end of the rift, erupted first, then magma pushed up through the middle of the rift area and began “unzipping” the rift in both directions, the researchers explained in a statement today. “We know that seafloor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this” [LiveScience], says study coauthor Cindy Ebinger.
The active volcanic region in Ethiopia’s Afar desert sits at the boundary of the African and Arabian tectonic plates, which have been gradually spreading apart for millions years; the new study shows that large-scale seismic events can speed up that process. The gradual separation has already formed the 186-mile Afar depression and the Red Sea. The thinking is that the Red Sea will eventually pour into the new sea in a million years or so [LiveScience].
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Image: University of Rochester
Federal experts believe that a major earthquake could trigger fires at Los Alamos National Laboratory, releasing radioactive materials and endangering lives. The rupture of a seismic fault that runs underneath the lab would shake the ground more than scientists previously thought, according to a new report (PDF). A natural disaster here would be bad news, since the lab, just west of Santa Fe, is the main plutonium factory in the United States, believed to hold thousands of pounds of plutonium for use in nuclear weapons (the actual amount is classified).
Researchers study plutonium inside glove boxes—a Hollywood movie staple, consisting of a sealed enclosure with gloves so that someone outside the box can work on dangerous materials inside. A major earthquake would shake the ground enough to topple the glove boxes, says the new study. Some glove boxes are enormous and even contain furnaces to cast and mold plutonium. If one of these were to crash, the resulting fire would be uncontrollable and would create a vaporized plutonium cloud that could drift outside of the lab, says the safety report. In a worst-case scenario, a fire could release so much airborne plutonium that a person on the boundary of the lab would get a dose of radiation—potentially many thousands of times greater than a chest X-ray—that could be fatal in weeks, according to individuals knowledgeable about the study [Los Angeles Times].
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According to a theory proposed in 2007, the explosion of a comet over North America killed off the Clovis people and many of the continent’s largest mammals nearly 13,000 years ago. Not so fast, says a new study published in the Proceedings of the National Academy of Sciences, fueling a WWE-style stare down between the opposing camps.
The new report explains that archaeologists have examined sediments at seven Clovis-age sites across the United States, and found that the concentration of magnetic debris was insufficient to confirm an extraterrestrial impact at that time [Nature News]. The original theory’s evidence came from magnetic microspherules, or cosmic debris, discovered in sediments at 25 locations. However, one of the new study’s authors, Todd Surovell, said that even after 18 months of sedimentary analysis and hundreds of hours peering into a microscope, he could find no evidence of microspherules to support the the exploding comet theory. Snap.
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Some of the world’s baddest volcanoes, like Chile’s Chaitén volcano that erupted in 2008, are actually even worse than scientists previously thought. A study of Chaitén’s eruption revealed that locals only had 30 hours to to flee from first time they felt rumbling, not the weeks or months that it typically takes a volcano to go from tremors to eruption. That’s because Chaitén is a rhyolitic volcano; these volcanoes are largely fueled by a silica-based, very flow-resistant magma and they tend to build pressure over time before erupting violently [National Geographic News]. Thousands were able to escape before Chaitén’s blast, but scientists are warning that others living in the shadow of a rhyolitic volcano may not be so lucky.
The magma of the Chaitén volcano traveled up to 3 feet per second, according to the study published in Nature. It shot from a depth of more than five kilometres [3 miles] to the surface in about four hours…. The violent and unexpected nature of the blasts, together with their rarity, means the Chaiténeruption is the first rhyolite event to have been scientifically assessed in this way [ABC News]. In the U.S. there are large rhyolitic volcanoes in Wyoming, California, and New Mexico as well as in the Japanese islands and New Zealand’s Taupo Volcanic Zone. Scientists are saying that even though rhyolitic eruptions are rare, the study should serve as a warning call to step up monitoring of potentially active volcanoes.
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Image: Jonathan Castro
Here’s a timely piece of research that may inspire some trepidation, as it comes hard on the heels of Tuesday’s tsunami-triggering earthquake in the South Pacific and today’s destructive earthquake in Indonesia. Researchers have found evidence that major quakes can weaken faults on the other side of the world, increasing the chance of further tremors.
The researchers analyzed 20 years of data at Parkfield, which sits on the mighty San Andreas Fault halfway between Los Angeles and San Francisco. It’s the most studied earthquake zone in the world, rigged with sensitive instruments to detect minute changes in the Earth’s crust [AP]. In 2004, the seismic records showed a change beginning shortly after the 9.3 magnitude earthquake in Sumatra that caused a deadly tsunami.
There was an increase in the number of small “repeating earthquakes” that regularly shudder through the ground around the San Andreas fault. Study coauthor Taka’aki Taira says that “after Sumatra, the frequency changed – it increased – but the magnitude decreased. That is a signal of the fault weakening; you only have to push a little bit and the fault fails” [BBC News].
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In an ambitious attempt to assess how humans are doing as stewards of planet earth, 28 leading scientists have drawn up a list of nine “planetary boundaries” that must not be crossed if we want to avoid drastically changing the global environment and imperiling our own existence. The only problem is, we’ve already crossed three of those thresholds.
The paper, published in Nature (and available for free), aims to define a “safe operating space” for human life on the planet. It’s a first-draft users’ manual for an era that scientists dub the “anthropocene,” in which nearly seven billion resource-hungry humans have come to dominate ecological change on Earth [Wired.com]. What follows is a list of the nine environmental factors, and how we’re doing on living within each limit.
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Geothermal energy, a promising but increasing controversial type of alternative energy, is on the hot seat again, this time in a German town that experienced an earthquake that some are blaming on the local geothermal power plant. A government panel is investigating claims that the plant triggered a magnitude-2.7 earthquake on 15 August in the town of Landau…. If the panel finds against the company that built the plant, Geox of Landau, it could be shut down [New Scientist].
Geox hasn’t been very vocal about the cause of the quake, but company officials initially denied any responsibility for the temblor and continue to dispute the government’s data linking the project to the quake. The panel will, among other things, have to sort through the conflicting data presented by the company and government scientists [The New York Times].
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Nitrous oxide, also known as laughing gas, might sound like a humorous substance. But here’s a sobering fact: The chemical now poses the largest man-made threat to the ozone layer, according to a study published in Science. Environmental policies, which have focused on controlling emissions of compounds such as CFCs, have largely ignored nitrous oxide. CFC levels have been falling since the 1989 adoption of the Montreal Protocol on Substances that Deplete the Ozone Layer… Meanwhile, nitrous oxide levels have been climbing as a result of increased emissions from agricultural fertilizers, biomass burning and animal waste [Nature News].
Researchers used a model to compare the potential of various gases, including laughing gas, to deplete the ozone layer, compared to a compound called CClF3, a substance with one of the greatest potentials for destroying the ozone. They found that although the threat that nitrous oxide poses to ozone is small compared to CClF3, the large-scale emissions of laughing gas mean it is the most significant of the ozone-depleting substances emitted by human-related activities today…. “This is the first time someone has dealt with nitrous oxide in isolation like this,” says atmospheric chemist Susan Solomon. “It’s one of those things that has simply been overlooked” [Nature News].
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Image: iStockPhoto
The groundwater of northern India is being drained away by irrigation faster than it can be replenished by the annual monsoon rains, and new satellite data shows that the process is accelerating. In an area that’s home to about 10 percent of the world’s people, that could be a recipe for disaster, policy experts say. A growing population with an increasing standard of living will only boost the demand for groundwater, a trend that could eventually lead to a reduction in agricultural yields, shortages of potable water and an increase in societal unrest [Science News].
The Gravity Recovery and Climate Experiment (GRACE) is comprised of a pair of satellites that measure subtle variations in the Earth’s gravity, caused by the movement of water either in the oceans or under the ground. Most famously, GRACE has recorded the shrinking of ice sheets; it has also detected shifting ocean currents, the desiccation of droughts, and the draining of large lakes [ScienceNOW Daily News]. Now two new studies of GRACE’s data have revealed the loss of groundwater from northern India; once water is pumped up from the aquifers for use in irrigation, it either flows away from the region or evaporates.
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