Physics Today: The magnitude-7.9 earthquake that struck near Chengdu city yesterday has caused thousands to lose their lives and made millions homeless. It is the largest earthquake to hit China since 1976. According to the US Geological Survey the quake occurred as the result of motion on a northeast striking reverse fault or thrust fault on the northwestern margin of the Sichuan Basin. The earthquake's epicenter and focal-mechanism are consistent with it having occurred as the result of movement on the Longmenshan fault or a tectonically related fault. The earthquake reflects tectonic stresses resulting from the convergence of crustal material slowly moving from the high Tibetan Plateau, to the west, against strong crust underlying the Sichuan Basin and southeastern China (see maps below). "Earthquakes in this part of China are infrequent but no unexpected" says Harley Benz, Scientist-in-Charge with the National Earthquake Information Center with the USGS.
The city of Chengdu has a population of 2 million, with another 9 million in the surrounding urban area, is about 90 km southeast of the epicenter. Many western companies such as IBM, Symantec, Microsoft, Intel, Fujitsu, NEC, Motorola, and Nokia have factories and offices in the region due to Chengdu's High-Tech Industrial Development Zone. None of these companies are reporting major damage to their staff or facilities. The sina web site has photos of the damage done in the city and surrounding towns.
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On a continental scale, the seismicity of central and eastern Asia is a result of northward convergence of the India plate against the Eurasia plate with a velocity of about 50 mm/y. The convergence of the two plates is broadly accommodated by the uplift of the Asian highlands and by the motion of crustal material to the east away from the uplifted Tibetan Plateau.
"For this earthquake, because of its size, we should expect to see lots of aftershocks," says Benz. "In the first few hours following the magnitude 7.8, we recorded more than 13 earthquakes, the largest being a magnitude 6. The earthquakes are being located along a northeast trending fault, and they extend over a region about 100 kilometers or 60 miles, which is consistent with the size of this earthquake."
"In terms of the total number of aftershocks, aftershocks form an earthquake, typically this size, will be occurring weeks and months from now, but typically with time, the number of earthquakes will go down, and the size of the earthquakes will go down, but there are chances of having other large, damaging earthquakes as part of this sequence occurring in the new few days and weeks."
New Scientist: Flakes of iron snow could be falling inside the planet Mercury, according to a new experiment. This hot metal snowfall might help generate Mercury's puzzling magnetic field. Researchers in the US have attempted to recreate the likely conditions within Mercury's liquid outer core, which is thought to be a mixture of iron and sulphur. They used an arrangement of magnesium-oxide blocks, called a multi-anvil cell, to squeeze their iron and sulphur mixture to immense pressures, at temperatures above 2000 °Celsius. Iron crystals formed in the mixture. "We saw iron crystals gathered at the bottom of the sample, while the liquid phase stayed on top," says team member Jie Li of the University of Illinois in Urbana-Champaign. Mercury's iron snow should form simple cubic crystals, rather than the intricate hexagonal patterns of water-ice snowflakes on Earth.
Related article
Non-ideal liquidus curve in the Fe-S system and Mercury's snowing core, Geo. Rev. Lett 35, L077201
Nature: Fifteen-year oscillations in Saturn's equatorial stratosphere bear a striking resemblance to the shorter-term oscillations seen on Earth and Jupiter — akin to notes played on a cello, a violin and a viola.
space.com: Sand grains stirred up by the winds of Mars are tossed higher and farther than those kicked up by winds on Earth, a new study finds. The results could help explain how dunes migrate across the Martian surface as well as what whips up dust storms that blow across the red planet. Scientists first noticed dunes on the Martian surface in pictures taken by NASA's Mariner missions in the 1970s and have seen dust storms of all sizes spread across the planet — one major storm in 2005 was even visible through a simple backyard telescope. But these features have puzzled astronomers because Mars has almost no atmosphere and very weak winds that seem unlikely to be able to sculpt dunes or whip up storms. To help solve this conundrum, a team of scientists recently conducted wind tunnel simulations of windblown sand grains under the conditions found on both Earth and Mars to figure out how the particles would behave on these planets with vastly different atmospheres. Their results are detailed in the April 28 issue of the journal Proceedings of the National Academy of Sciences.
Science: More than 400,000 asteroids have been identified in the solar system to date. These objects are thought to be the surviving remnants of the planetesimals that formed the planets about 4.6 billion years ago. The ages and mineralogical characteristics of these planetesimals can be estimated through high-precision laboratory analyses of the compositional and isotopic properties of meteorites, of which more than 30,000 samples exist.
Until now there has been no way to estimate when an asteroid formed, other than assuming that its age was similar to that of most meteorites. In the 25 April Science there is a new paper that present results of a remote spectroscopic study to show that a number of asteroids are enriched in the oldest known objects in the solar system (calcium-aluminum inclusions or CAIs), thereby making them the most ancient asteroids currently known.
The Guardian: We may not be able to travel to the centre of the Earth, but computer models have helped further our understanding of what's under our feet.
Technology Review: Earthquake researchers in California hope to take advantage of the motion sensors in laptops to create an earthquake-sensing network. By putting computers in homes and businesses to work as seismic monitors, the researchers hope to pull together a wealth of information on major quakes, and perhaps even offer early warnings, giving a few seconds' notice of a potentially devastating quake. The Quake Catcher Network (QCN) is in the beta testing stage, with links to several hundred laptops. It's a distributed computing network, like SETI@home, which searches for intelligent signals from space, and Folding@Home, which focuses on protein folding. Machines in the earthquake network would monitor motion and report big shakes to a central server. If a horde of reports came in from a particular area, it could indicate an earthquake. The network will initially focus on the quake-prone San Francisco Bay and the Greater Los Angeles Basin areas of California.
New Scientist: A group of icy objects in the outer solar system appear years younger than their suspected age--1 billion years old.
The largest member of the family, called 2003 EL61, was discovered in 2005. In 2007, astronomers found five smaller objects travelling in similar orbits. Their paths suggested they all formed a single object that was broken apart in a collision more than a billion years ago.
A team led by David Rabinowitz of Yale University in New Haven, Connecticut, US, have released a paper on Arxiv that the brightness of the large object and four of the smaller ones (the fifth could not be observed) changes little when observed from various points along Earth's orbit. That suggests their surfaces are covered with fresh powdery ice no more than 100 million years old.
Nature: After a 30-year gap, all eyes are back on Mercury as the MESSENGER probe gives us our second glance at the Sun's nearest neighbour. Hints of intriguing results to come are already at hand
BBC news: Nasa's Stereo orbiters have captured stunning new images of spaceborne debris thrown out from the Sun. The twin spacecraft have seen Coronal Mass Ejections (CMEs) hurling material into a comet, ripping off its tail. Scientists hope the probes will allow better forecasting of CMEs, which sometimes disrupt communication systems on Earth.
BBC News: Scientists have completed the first stage of an ambitious plan to drill down into an earthquake-generating region near Japan. The project saw holes bored 1.4km into the sea floor, producing 3D images of stresses inside the quake zone. The Nankai Trough produced major lethal earthquakes and tsunami during the last century. The eventual aim is to place instruments 6km deep in the crust, possibly as an early warning system. Findings from the initial phase of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) were presented here at the European Geosciences Union (EGU) annual meeting.
Reuters: China will complete a new research station in the interior of Antarctica next year, state media said on Sunday, expanding its presence on the continent. The official Xinhua news agency cited Sun Bo, head of the Chinese Antarctic expedition team, as saying that an expedition to start in November would build the main structure of the new station situated on Dome A, the highest point on the continent at 4,093 meters above sea level. The country's third scientific research station on the continent, it is expected to be finished by next January, Xinhua cited Sun as saying after returning from the country's 24th scientific expedition there.
Science: Earth has its high-standing continents and low-lying ocean basins, thanks to plate tectonics. And Mars has its smooth northern lowlands and its cratered highlands. But there's no credible sign that plate tectonics ever operated on Mars, so how did a third of the planet come to be as much as 4 kilometers lower than the rest? For the past quarter-century, a leading theory has held that a giant impact battered the young planet and excavated the northern lowlands, but that idea seemed to have serious problems.
Now, two new studies purport to ease the difficulties with a giant impact. In one study, researchers reveal the true dimensions of the huge "Borealis basin," making it look much more like the crater of a giant impact. And a second group has run simulations that suggest how an impactor could have blasted out an 8000-kilometer-wide crater without melting it into an unrecognizable puddle of magma. "I think there's much to recommend [a giant impact] now with all this new work," says Sean Solomon, a planetary geophysicist at the Carnegie Institution of Washington's Department of Terrestrial Magnetism in Washington, D.C.
LA Times: Fault-laced Southern California has a greater chance of a huge quake by 2038 than the North, researchers say.
Southern California stands a greater chance of a huge temblor in the next 30 years than Northern California, according to a statewide earthquake forecast released Monday.
Nature: Eruption in 1600 may have plunged the globe into cold climate chaos.
LA Times: The rock believed responsible for a mass extinction 65 million years ago was much smaller than previously thought, scientists say.
The asteroid that wiped out the dinosaurs may not have been the whopper scientists thought.
USA Today: NASA's new Mars rover aims high. It's bigger, more powerful and more sophisticated than any other robotic vehicle that has landed on another planet. It will try to answer a big question: Has life existed elsewhere in the solar system?
Its very ambition has gotten the rover in trouble. Thanks to a mix of technological setbacks and engineering misjudgments, the rover's epic scale is matched by epic problems.
The new rover, known as the Mars Science Laboratory, is $235 million, or 24%, over budget. Work on it has run so late that engineers are racing to prepare the rover for its blastoff in 2009. After that, the next good launch window, when Mars and the Earth are closest, is in 2011.
"They aimed high, and they got burned," says Arizona State University's Phil Christensen, a Mars scientist who helped review NASA's Mars program.
space.com: Astronomers have finally tracked down the missing starting point of one of the two types of solar wind.
The solar wind is a stream of electrically charged particles that flows constantly out from the sun in all directions. The particles can make the journey from the sun to the Earth in fewer than 10 days and, when the wind turns into a storm, create the magnificent auroras that dance across polar skies when they interact with the Earth's magnetic field.
The parts of the solar wind that emanate from the sun's equatorial region originate at the edges of bright regions in the sun's atmosphere and are released when the magnetic fields of two bright regions link up, scientists announced last week at the Royal Astronomical Society's National Astronomy Meeting in Belfast, Northern Ireland.
Nature: If a day seems to go by faster now than it did when you were younger, it might not just be your imagination. The speed of the Earth’s rotation is known to fluctuate slightly over decades. Now researchers have found a piece of the puzzle to explain this drift: a highly conductive mineral that could change the way the Earth spins.
Science: "It's all a mush in my mind," said Michael Carr, talking about early Mars. That's quite a concession from one of the world's most experienced Mars geologists. After 10 hours of discussion on the state of early Mars, "it's frustrating," he said when asked to sum up a small premeeting workshop.* "Despite the beautiful data we've seen, we're no closer to understanding what [early Mars] climate was. And if it was warm and wet, what caused it to be warm and wet?"
Carr, who has been studying Mars since the early 1970s at the U.S. Geological Survey in Menlo Park, California, wrote the book on Mars. Actually, he wrote two of them: Water on Mars and The Surface of Mars. But that wasn't enough to sort out 40 years of data, much of it still coming from two rovers and two orbiters. The workshop focused on the first period of martian geologic history, called the Noachian--when water flowed on the surface, at least at times--and the transition into the Hesperian, a colder, drier time preceding the bone-dry deep-freeze of the past 3 billion years.
New York Times: Back in 2002, astronomers from Wesleyan University concluded that a star brightening and waning in an unusual 48-day rhythm was dipping in and out of stuff swirling around the star in a so-called protoplanetary disk. At the time one astronomer called the system “a Rosetta stone,” for understanding how planets form.
Now, after six more years of observation with an international group of astronomers, led by William Herbst of Wesleyan, researchers say they know what the stuff in this disk is. In a paper published on Thursday in the journal Nature, they report that it is made of sand-size grains, roughly a millimeter in diameter, which must have grown from infinitesimal dust particles over the three million years that the star, known as KH 15D, has been in existence.
New York Times: Mikki M. Osterloo of the University of Hawaii and colleagues have found evidence of chloride-bearing materials — in other words, salts — in the Martian southern highlands. The deposits are small and in some cases are fractured into polygonal shapes, suggesting that they consist of salts that precipitated out of saline water as it evaporated, which is how salt flats form in deserts on earth.
CNN: NASA officials have directed the Mars Exploration Rover (MER) program to cut $4 million dollars from its $approximately 20 million dollar budget this year, and principal investigator Steve Squyres tells CNN that will likely mean science operations will have to be suspended for Spirit. The rover would be put in hibernation mode, and if all goes well it could be reactivated in the future in the event funding is restored.
Source: NASA/JPL-Caltech/Cornell
NASA Headquarters spokesman Dwayne Brown confirmed the budget directive has been issued. He said the reason behind the cut is to offset cost overruns with the Mars Science Laboratory, a follow-on rover set to launch next year.
Washington Post: Since astronomers identified the first planet outside our solar system 13 years ago there are now, according to the Extrasolar Planets Encyclopedia, 277 confirmed "extrasolar" planets, and quite a few more on the list of those suspected but not yet confirmed.
This explosion in planetary discoveries is taking place at such speed that even those most intimately involved are often amazed.
"This is an absolutely astounding time for this field," said Mark Swain of NASA's Jet Propulsion Laboratory, who last week reported finding the first "exoplanet" to have organic methane in its atmosphere.
The Washington Post conducted a discussion forum with MIT's Sara Seager on the state of extra planetary research on Monday afternoon.
New York Times: A new book, “Unknown Waters,” recounts the 1970 voyage of a submarine, the Queenfish, on a pioneering dive beneath the ice pack to map the Siberian continental shelf. The United States did so as part of a clandestine effort to prepare for Arctic submarine operations and to win any military showdown with the Soviet Union.
In great secrecy, moving as quietly as possible below treacherous ice, the Queenfish, under the command of Alfred S. McLaren, mapped thousands of miles of previously uncharted seabed in search of safe submarine routes. New York Times reporter William J. Broad talks to McLaren about his year-long voyage and the dangers of submarining under the Arctic pack ice.
Related links
Scientist at work: Alfred McLaren; Explorer of Arctic Depths Plans Another Trip North (New York Times October 29, 2002)
Science: Since 2004 the Cassini-Huygens mission has been observing Saturn's moon Titan. The satellite moon, which is covered in a dense methane-based atmosphere, is unobservable in the visible spectrum, but based on the size of the moon and the pressure reached at the surface, for years it was generally believed to have a liquid hydrocarbon-based ocean. The radar on Cassini spacecraft, and the descent of the Huygens probe to the surface in January 2005 radically changed our perspective of the moon, to that of a planetary body that consisted of a solid surface, full of geological features such as dunes, channels, lakes, impact craters.
Now a research team led by Ralph D. Lorenz at Johns Hopkins University Applied Physics Laboratory, have announced a new startling conclusion. The features researchers saw three years ago have drifted position, which leads them to conclude that Titan has an ocean buried below several tens of kilometers of ice.
“I think the paper is basically sound,” said David J. Stevenson from the California Institute of Technology to the New York Times reporter Kenneth Chang. “They have data to support the idea that the outer shell of Titan is moving relative to the deeper part, and the cause of this movement is a stress exerted on the shell.”
Related Links
Report: Titan's Rotation Reveals an Internal Ocean and Changing Zonal Winds (Science)
Perspective: Titan's Hidden Ocean (Science)
Surf’s down on Titan, 50 miles below the surface, scientists say (New York Times)
Science: Planetary systems are born around young stars and grow from vast clouds of dust and gas called protoplanetary disks. Models predict that as our own solar system's protoplanetary disk evolved, the dust and gas pushed each other around while constantly being stirred and jolted by magnetic fields and gravitational torques. The resulting mixing and motion set the chemical compositions of the planetesimals that formed and from which planets eventually grew. Although evidence for mixing is found in objects in our solar system, such as primitive meteorites, questions remain about the details of the processes responsible and whether this mixing was common in other protoplanetary disks. A new paper in Science on observations of the disk around the star AA Tau that suggest that we will soon be able to address these questions.
BBC: A pair of meteorites discovered in Antarctica are in a class all of their own, says Ryan Zeigler, from Washington University in St Louis, US at the 39th Lunar and Planetary Science Conference. The paired meteorites, known as GRA 06128 and GRA 06129, were discovered in the Graves-Nunataks region of Antarctica in 2006.
The rusty, slab-shaped rocks have defied classification, not fitting into any of the existing groupings drawn up for meteorites. Researchers are pondering where in our Solar System the meteorites could have originated. The current best estimate is that they are not from a major planetary body, but from an astroid instead.
Related Link
Petrology and geochemistry of Dhofar 733 - An unusually sodic, feldspathic lunar meteorite
Space.com: NASA's Mars Reconnaissance Orbiter (MRO) has captured some images that suggest the debris-strewn Holden Crater once held a calm body of water. The crater debris includes a mix of broken boulders and smaller particles called megabreccia.
 "Holden crater has some of the best-exposed lake deposits and ancient megabreccia known on Mars," said Alfred McEwen, principal scientist for MRO's HiRISE camera. "Both contain minerals that formed in the presence of water and mark potentially habitable environments. This would be an excellent place to send a rover or sample-return mission to make major advances in understanding if Mars supported life."
Science: Some 17 million years ago, the Grand Canyon started to form according to geologists at the University of New Mexico, led by Victor Polyak, who used a used an improved uranium-lead dating technique, which yields ages of mineral back tens to hundreds of million years.
By dating mineral deposits inside caves up and down the canyon walls, the geologists said they determined the water levels over time, as erosion carved out the mile-deep canyon as it is known today. They concluded that the canyon started from the west, then another formed from the east, and the two broke through and met as a single majestic rent in the earth some six million years ago.
Previous theories had posited six million years as the earliest age for the beginning of the entire Grand Canyon of the Colorado River.
NPR (audio): The region of the ocean known as "the desert of the sea" has expanded dramatically over the past decade, according to a new study in Geophysical Research Letters.
LA Times: An atomic-powered craft, being built at the Jet Propulsion Laboratory and scheduled for a 2009 launch, aims to settle once and for all whether the planet has ever been suitable for life.
The New York Times: In the craggy terrain around the Moon’s south pole, the deepest craters dip 2.5 miles beneath the surface while the peaks reach as high as the highest mountain in North America — a 37,000-foot change of elevation.
The Christian Science Monitor: The Anthropocene epoch would mark the period when humans became the predominant force over the Earth's environment.
ScienceNow: Officials with NASA and the National Oceanic and Atmospheric Administration (NOAA) have decided to add a key climate sensor to a satellite scheduled to launch in 2010, ScienceNOW has learned. Scientists say the move will help ensure a continuous 22-year data set on climate change, which has been threatened by a Pentagon plan to strip six climate sensors from a key Earth-observing satellite (Science, 31 August 2007, p.1167).
ScienceNews: Supposedly, there's no place like home. But a new study suggests that earthlike planets orbit or are forming around many, if not most, nearby sunlike stars, providing places where life might have gained a foothold.
The New York Times: The American Geophysical Union, the world’s largest organization representing earth and space scientists, put out a fresh statement on the causes and consequences of recent climate change and possible responses.
ScienceNow: Researchers have found evidence that a previously undiscovered active volcano, which last erupted about 2300 years ago, could be heating a portion of the West Antarctic Ice Sheet, causing enough melting to nudge the sheet toward the sea. The find is bad news for scientists already worried about the stability of the giant ice sheet as global temperatures climb.
ENN: Scientists have discovered a layer of volcanic ash and glass shards in Antarctica, evidence of an old eruption by a still active volcano that researchers believe may be contributing to the thinning of Antarctic glacial ice.
Hugh F.J. Corr and David G. Vaughan, two scientists with the British Antarctic Survey, recently published their discovery of the volcanic layer in the journal Nature Geoscience. The discovery is unique according to Dr. Vaughan. He said “This is the first time we have seen a volcano beneath the ice sheet punch a hole through the ice sheet.”
Los Angeles Times: Launched by Stanford University and Monterey Bay Aquarium and its research institute, the organization was created in part out of frustration from a lack of government leadership.
The Christian Science Monitor: Scientists are puzzled, but the phenomenon seems to fit the latest global-warming models.
ScienceNow: Time and tide may wait for no man, but continents occasionally do. That's the conclusion of a study published today in Science, which finds that the inexorable drift of Earth's tectonic plates isn't inexorable at all. In fact, the planet could be headed for another pause in continental drift, with uncertain and possibly ominous consequences.
Science News: The planet's wandering magnetic poles help reveal history of Earth and humans
BBC: A new idea could explain how the climate of early Mars became warm enough to support oceans.
NPR: "Rogue waves" are monsters of the open ocean — the powerful "walls of water" can destroy even large ships. Satellite measurements have found them to be up to 100 feet tall. So far, scientists have disagreed about what causes the waves, but researchers at UCLA think that they may have found a clue.
Nature: Sahara Desert could become home to solar-power plants.
National Geographic News: The intensities of strange, long-lasting tremors in North America's Pacific Northwest ramp up and quiet down with the rise and fall of the ocean's tides, according to a new study.
The Independent: New geological data published yesterday in the journal Science looks at the behavior of seething layers of molten magma, super-heated gases and hydrothermal liquids underneath Yellowstone National Park. The magma is on the move, and so is Yellowstone.
Over the past three years, according to the report, the ground in the volcanic caldera that spans about 925 square miles and accounts for much of the park's terrain has been rising towards the sky at the rate of almost three inches per year. That is three times faster than has ever been observed before. It raises the obvious question: what is happening under the park? And what might be about to happen?
New Scientist: A previously undiscovered type of aurora could be brightening the skies over the poles. That's the conclusion from satellite images of the poles showing the new phenomenon above Antarctic in 2004 says New Scientist's Catherine Brahic.
Continue reading "New kind of polar aurora" »
The New York Times: An earthquake rattled the Bay Area on Tuesday night, and in many ways it was just a pre-Halloween scare that did little damage, injured no one and barely merited a break-in to prime time broadcasting.
MSNBC: Further observations could be used to monitor violent solar outbursts
San Francisco Chronicle: The last time a major earthquake ripped along the Hayward Fault, San Leandro and Hayward were nearly leveled, but, in a shock to seismologists, the most populated stretch of the East Bay was relatively unscathed, according to a new map released Wednesday
Nature: India's crash into Asia was driven by plate thickness.
MSNBC: Scientists figure out how eons of eruptions contribute to Io’s atmosphere
Los Angeles Times: Core samples taken 2 miles deep reveal that the answer to having plates slip past one another without a quake may be baby powder.
Science: The recent run of large quakes off the Indonesian island of Sumatra is providing fodder for both sides in the debate over whether earthquakes behave consistently enough to be reliably anticipated.
MSNBC: Researchers recreated crushing conditions within planet's lower mantle
National Geographic News: Swirling eddies and chaotic vortices are crucial to the formation of new planets, suggests a counterintuitive new study.
The New York Times: Thousands of miles of fiber-optic cables are strung across the world’s oceans, connecting continents like so many tin cans in this age of critical global communication. So the fact that about 800 more miles of fiber-optic cable will soon thread the sea floor off the coast of the Pacific Northwest might not seem particularly revolutionary. Until you meet John R. Delaney, part oceanographer, part oracle.
Science: Particle physicists and g |
