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.
(more…)
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.
Related Content:
80beats: In the Permian Period, Erupting Super-Volcanoes May Have Killed Half the Planet
80beats: Forget “The Asteroid”: Could Supervolcanoes Have Killed the Dinosaurs?
80beats: Undersea Volcanoes Decimated Marine Life in the Primordial Oceans
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].
(more…)
The tsunami that struck the South Pacific islands of Somoa, American Somoa, and Tongo yesterday has resulted in at least 108 deaths, according to early reports.
Experts monitoring the underwater earthquake that triggered the tsunami have issued various reports of its magnitude, ranging from 7.8 to 8.3. The powerful quake struck early on Tuesday morning, local time, as island residents were getting ready for work and school. About ten minutes after the shock, ten-foot-high waves hit American Somoa’s shore. “American Samoa is a small island, and most of the residents are around the coastline,” [said Filipo Ilaoa, deputy director of the American Samoan office in Honolulu]. “There was no warning or anything at all. By the time the alert was out of the Pacific Tsunami Warning Center, it had already hit” [The New York Times].
(more…)
A 8.3 magnitude earthquake in the South Pacific triggered a tsunami early Tuesday morning local time (5:48 pm Greenwich Mean Time), sending residents of the Samoan Islands running to the hills. At this time there are unconfirmed reports of scattered deaths in American Samoa. The powerful waves reportedly swept into Pago Pago, American Samoa’s capital city.
To the west, in the independent state of Samoa, at least one coastal village was leveled, according to eyewitness Graeme Ansell of New Zealand. “It was very quick. The whole village has been wiped out,” Ansell told National Radio from a hill near Samoa’s capital, Apia. “There’s not a building standing. We’ve all clambered up hills, and one of our party has a broken leg. There will be people in a great lot of need ’round here” [AP].
Related Content:
80beats: Indonesia May Face a “Supercycle” of Devastating Earthquakes
80beats: Geologists Find One Cataclysmic Tsunami in Every 600 Years of Thai Dirt
Image: flickr / epugachev
Forget, for a moment, all those fancy geoengineering schemes that would alter the face of the planet in an attempt to reduce global warming’s impact. Population scientists argue that a cheaper and simpler strategy is to hand out birth control to those who want it–especially to people in the developing world, where birth rates are booming.
The world’s population is projected to jump to 9 billion by 2050, with more than 90 percent of that growth coming from developing countries…. In countries with access to condoms and other contraceptives, average family sizes tend to fall significantly within a generation. Until recently, many U.S.-funded health programs did not pay for or encourage condom use in poor countries, even to fight diseases such as AIDS [AP].
(more…)
The Mount Wilson Observatory has allowed astronomers to gaze at the heavens for more than a century from a peak in the San Gabriel Mountains, just northeast of Los Angeles, but the devastating conflagration known as the Station Fire that ripped through the Angeles National Forest over the past week had stargazers wondering if the historic facility was about to go up in smoke. The flames got so close at one point that firefighters abandoned the facility, but now L.A. County Deputy Fire Chief Jim Powers has assured astronomers that he foresees “another hundred years for Mount Wilson Observatory.” This is the story of how firefighters saved the birthplace of modern astronomy as well as a virtual forest of communication towers that serve the region [AP].
On Monday night, the scene was grim. The observatory had been hastily evacuated that day, and only two-dozen firefighters stood overnight sentry, positioned along the gloomy perimeters of the observatory and towers. A greater number might have been deployed, but there were more pressing priorities in the urban elevations — the protection of hillside homes [Los Angeles Times]. By daybreak, fire chiefs made the call to retreat from the mountaintop, where firefighters could easily be trapped by the oncoming flames. “It’s not worth dying for,” said Los Angeles County Fire Department Battalion Chief Steve Martin [Los Angeles Times].
(more…)
In a series of dramatic (if blurry) photographs, scientists have captured a rare type of lightning known as a “gigantic jet.” These jets strike up from the thunderclouds instead of down from them towards the earth, according to findings published in Nature Geoscience.
Catching the phenomenon on film has boosted scientists’ understanding of the lightning. “These are not just sparks that come out of the thunderstorm and travel upward and tickle the upper atmosphere. They actually deliver to the upper atmosphere as much electric charge as the very strong lightning strokes to ground” [BBC], says lead author Steven Cummer. Capturing gigantic jets as they occur is difficult because they occur infrequently, and because scientists don’t yet know which types of storms promote their formation. Cummer got his shot by luck. He had his cameras trained on the clouds brewed by the 2008 tropical storm Cristobal, hoping to spot another form of electrical discharge, when the jet blasted upward, reaching 40 miles into the upper atmosphere.
Related Content:
80beats: A Fleet of Professional Storm Chasers Will Study Tornado Genesis
80beats: Lightning May Have Created Special Food for Earth’s Early Microbes
DISCOVER: Juicing Up the Atmosphere has more on these strange jets
DISCOVER: Where Lightning Strikes
Image: Steven Cummer
Five patent applications for technology that aims to control the weather bear the signature of a man who knows how to think big: Microsoft founder Bill Gates. The applications made public by the U.S. Patent Office last week describe floating devices that could reduce the strength of hurricanes by drawing warm water from the ocean’s surface and channeling it down to the depths through a long tube. A second tube would reverse the process and bring deep, cold water up to the surface.
The applications were filed by an entity called Searete, which is part of the company Intellectual Ventures that was founded by former Microsoft executives as an “invention business;” Bill Gates is an investor in the company. Gates is listed as one of the inventors on each hurricane-quelling patent application, along with scientists like the geoengineering expert Ken Caldeira. One of the patent applications describes how part or all of the cost of building and maintaining the hurricane-killer ships could be raised by selling insurance to coastal residents whose risk would be reduced by using the new system [New Orleans Times-Picayune].
(more…)
In a central California area with a history of dramatic earthquakes, researchers have detected a worrisome amount of seismic activity deep underground. The researchers looked at data from 76 monitoring stations along the central California stretch of the San Andreas fault, and found that almost 2,200 “deep earth tremors” had shaken the earth since 2001, a span of time that included two earthquakes. Tremors increased around the time of those two quakes in 2003 and 2004, and rates have remained high since then. “What’s surprising is that the activity has not gone down to its old level” [Reuters], says study coauthor Robert Nadeau. It’s possible that the continuing tremors could presage another quake, researchers say.
Tremors vibrate quietly and can continue for days. Tremors also tend to happen in a deeper, softer part of the Earth’s crust, rather than in the upper part typically thought to generate earthquakes [Los Angeles Times]. Researchers don’t yet know whether tremors are accurate predictors of the larger earthquakes that can convulse the earth’s surface, but Nadeau says they may be a symptom of stress building up on a fault. “We’ve shown that earthquakes can stimulate tremors next to a locked (fault) zone, but we don’t yet have evidence that this tells us anything about future quakes,” Nadeau said…. “But if earthquakes trigger tremors, the pressure that stimulates tremors may also stimulate earthquakes” [San Francisco Chronicle].
(more…)
The state of Louisiana is losing its coastal wetlands to the Gulf of Mexico, and a new study suggests that conservationists won’t be able to turn the tide. If engineers don’t divert sediment-rich waters from the Mississippi River to help replenish a sinking river delta, about 10 percent of [the] state will slip beneath the waves by the end of this century. However, even if the engineers do try to abate the subsidence, the Mississippi doesn’t carry enough sediment to offset more than a small fraction of that loss, a new analysis suggests [Science News].
Before American settlers subdued the Mississippi and its tributaries, the river periodically overflowed its banks and spilled muddy water, thick with sediment, into surrounding wetlands. But the new study found that the Mississippi and Atchafalaya rivers today carry only half the sediment they did a century ago — between 400 million and 500 million tons a year then, compared with just 205 million tons today. The rest is now captured by more than 40,000 dams and reservoirs that have been built on rivers and streams that flow into the main channels [The Times-Picayune].
So even if Louisiana officials embark on an all-out campaign to restore the marshes through controlled levee breaks and diversion projects that bring back river water, it wouldn’t be enough to save the land–especially since sea levels are rising due to global warming. “We conclude that significant drowning is inevitable” [The Guardian], the study’s authors wrote.
(more…)
As of tomorrow, 101 years will have passed since the Tunguska Event, the mysterious explosion that flattened 800 square miles of Siberian forest. Just in time for the anniversary researchers have come up with yet another explanation for what may have caused the baffling blast. Previously, researchers best hypothesis was that a meteor struck the forest, but scientific expeditions failed to turn up an impact crater or any fragments of rock. The new hypothesis, which will be published in the journal Geophysical Research Letters, suggests that the Earth was hit by the icy core of a comet, which exploded in the atmosphere.
Researchers say that a comet strike would have released huge volumes of water vapour at very high altitude, creating highly reflective clouds that may explain why the sky was lit up for days after the collision, with people as far away as London saying that they could read newspapers outdoors at midnight, the scientists said [The Independent]. In an unusual twist, the evidence for the new theory comes from studies of the water vapor exhaust created by space shuttle launches.
(more…)
Earth scientists say that from all appearances, Taiwan should be rocked periodically by devastating earthquakes. The island sits on the boundary between the Philippine Sea tectonic plate and the Eurasian plate, and geologists describe the area as one of the most seismically active in the world. Here, the colliding plates move so rapidly that they build mountains at a rate of almost 4mm per year. [Researcher Alan] Linde said that in geological terms that is almost like “growing mushrooms”. “It’s surprising that this area of the globe has had no great earthquakes and relatively few large earthquakes” [BBC News], says Linde.
Now, Linde and his colleagues think they have an explanation for Taiwan’s seismic silence in the region’s typhoons–the tropical cyclones that originate in the northwest Pacific Ocean. Their new study suggests that the typhoons passing over the island have been triggering quakes that harmlessly release fault strain over hours and days rather than destructively over seconds or minutes. And these slow earthquakes, they speculate, may be staving off a big one [ScienceNOW Daily News].
(more…)
The explosion of a volcano located in present-day China might have caused a mass extinction 260 million years ago, adding more evidence that volcanoes might have been to blame for some of the world’s most catastrophic die-offs. Because the eruptions occurred in a shallow sea the researchers were able to study both the volcanic rock and the overlying layer of sedimentary rock containing fossilized marine life [AP], giving researchers a better picture of how the explosion altered the balance of life.
The injection of hot lava in a sea would have produced a massive cloud formation that could spread around the world, cooling the planet and producing acid rain [AP], according to the study, which was published in Science and led by paleontologist Paul Wignall. Based on analysis of the volcanic and sedimentary rock at the eruption site, the scientists hypothesized that ash and lava spewed from a sea covering the volcano, showering plants and animals with atmospheric carbon. “When fast flowing, low viscosity magma meets shallow sea it’s like throwing water into a chip pan there’s spectacular explosion producing gigantic clouds of steam” [Telegraph], says Wignall.
(more…)
West Africa has a history of severe, prolonged “mega-droughts,” according to a new study, and researchers say that another one is inevitable, although they can’t say when it might occur. Says lead researcher Tim Shanahan: “It’s disconcerting – it suggests we’re vulnerable to a longer-lasting drought than we’ve seen in our lifetime…. If the region were to shift into one of these droughts it would be very difficult for people to adapt; and we need to develop an adaptation policy” [BBC News].
The study, which examined sediment samples on a lake bottom to trace the climate history back 3,000 years, reveals that the infamous 1970s drought of the African Sahel region, which lasted several decades and killed more than 100,000 people, was actually a “minor” event…. “What’s disconcerting about this record is that it suggests the most recent drought was relatively minor in the context of the West African drought history” [New Scientist], says Shanahan. The researchers found that decades-long droughts similar to the 1970s event occur every 30 to 60 years, but that even more severe, century-long droughts have reoccurred as well. The most recent mega-drought began in 1400 and lasted until 1750, during which time forests grew up in dry lake beds.
(more…)
