just haze .. they say the ash has traveled the world twice, and don't expect it back again, as it would be unprecedented .. that is no guarantee of course, as 'unprecedented' is ever more common today ..
anyway, for those who haven't seen volcanic ash in the sky .. take it from me, it looks like very albeit 'clean', ordinary pollution haze .. Sydney airport was shut down last night and still no planes today .. pluses are .. one guy i heard interviewed this morning is doing a rollicking coffee trade at the airport now .. stranded passengers are having an unprecedented, for many am assuming anyway, unique experience ..
AND .. IT IS WONDERFULLY QUIET for those of us who live by the airport .. lol ..
Excuse please, this off-politics post .. aside, check out the beautiful pictures back two and around .. even if it is again .. heh ..
Antineutrinos reveal a primordial source of Earth’s radiated heat
Every second, Earth expels 44 terajoules of energy into space. Much of that energy arises from the decay of radioactive isotopes, principally uranium-238 and thorium-232. The remainder flows from an energy reservoir created billions of years ago, as our planet formed and gravitational potential energy was converted into heat. (Subsequent radioactive decay also contributed to that reservoir.) Now the Kamioka Liquid-Scintillator Anti-Neutrino Detector (KamLAND) collaboration reports that 24 ± 9 TW of the radiated power has a radiogenic origin; the remaining heat flux—about half—is primordial. In deriving that conclusion, the researchers combined seven-plus years of their own observations of antineutrinos formed in Earth’s interior and measurements obtained from the Borexino experiment in Italy. KamLAND’s mineral-oil-filled detector (see the figure; the person at the top gives the scale) observed 841 antineutrino events at energies consistent with 238U or 232Th decay. The great majority of those were background events that were generated by reactions at nearby nuclear facilities and that yielded much of the collaboration’s statistical error. Ironically, the experiment benefited from a natural catastrophe: Background flux was significantly reduced beginning in July 2007, when the Kashiwazaki–Kariwa nuclear power station was completely shut down for 21 months following a magnitude 6.6 earthquake. (A. Gando et al., KamLAND collaboration, Nat. Geosci., in press, doi: 10.1038/ngeo1205.)—Steven K. Blau
Radioactive decay accounts for half of Earth's heat
It's hot down there, thanks in part to radioactive decay Courtesy: Berkeley Lab
Hamish Johnston Jul 19, 2011
About 50% of the heat given off by the Earth is generated by the radioactive decay of elements such as uranium and thorium, and their decay products. That is the conclusion of an international team of physicists that has used the KamLAND detector in Japan to measure the flux of antineutrinos emanating from deep within the Earth. The result, which agrees with previous calculations of the radioactive heating, should help physicists to improve models of how heat is generated in the Earth.
Geophysicists believe that heat flows from Earth's interior into space at a rate of about 44 × 1012 W (TW). What is not clear, however, is how much of this heat is primordial – left over from the formation of the Earth – and how much is generated by radioactive decay.
The most popular model of radioactive heating is based on the bulk silicate Earth (BSE) model, which assumes that radioactive materials, such as uranium and thorium, are found in the Earth's lithosphere and mantle – but not in its iron core. The BSE also says that the abundance of radioactive material can be estimated by studying igneous rocks formed on Earth, as well as the composition of meteorites.
As a result of this model, scientists believe that about 20 TW is generated by radioactive decay – 8 TW from the uranium-238 decay chain; 8 TW from the thorium-232 decay chain and the final 4 TW from potassium-40. Fortunately, these decay chains also produce anti-electron-neutrinos, which travel easily through the Earth and can be detected, thereby giving physicists a way to measure the decay rates and ultimately the heat produced deep underground.
Decay and measure
In 2005 researchers at KamLAND announced that they had detected about 22 such "geoneutrinos", while last year scientists at the Borexino experiment in Italy said they had detected 10. Now, the KamLAND team has bagged a total of 111 of these tiny almost massless particles. The combined results have allowed the KamLAND team to conclude that the heat flux due to the uranium and thorium decay chains is about 20 TW with an uncertainty of about 8 TW. While the KamLAND experiment cannot detect the lower-energy antineutrinos from potassium-40 decay, the researchers believe that the value predicted by the BSE model of 4 TW is correct.
Although 20 TW from uranium and thorium is more than the 16 TW predicted by the BSE model, it is still within the experimental uncertainty – and is much less than the total flux of 44 TW. "One thing we can say with near certainty is that radioactive decay alone is not enough to account for Earth's heat energy," says KamLAND collaborator Stuart Freedman of the Lawrence Berkeley Laboratory in California. "Whether the rest is primordial heat or comes from another source is an unanswered question."
One possibility that has been mooted in the past is that a natural nuclear reactor exists deep within the Earth and produces heat via a fission chain reaction. Data from KamLAND and Borexino do not rule out the possibility of such an underground reactor but place upper limits on how much heat could be produced by the reactor deep, if it exists. KamLAND sets this limit at about 5 TW, while Borexino puts it at about 3 TW.
Oil-filled balloon
The KamLAND detector is a huge balloon filled with 1000 tonnes of mineral oil that is monitored by more than 1800 photomultiplier tubes. It is located deep underground in a Japanese mine to shield the detector from cosmic rays.
Very occasionally an antineutrino will react with a proton in the oil to create a neutron and a positron. The positron travels a short distance through the oil, giving off a flash of light as it ionizes oil molecules. The positron then annihilates with an electron to create two gamma-ray photons. These two processes happen very quickly and the light can be detected by the photomultiplier tubes. In addition, the energy of the antineutrino can be estimated from the amount of light given off during ionization.
A few hundred milliseconds later, the neutron is captured by a proton to form a deuteron. This results in the emission of a gamma ray, which can also be detected by the photomultiplier tubes. By looking for signals in the photomultiplier tubes that are separated by the appropriate amount of time, KamLAND can discriminate between extremely rare antineutrino events and the much more common signals due to background radiation.
The work is described in Nature Geoscience 10.1038/ngeo1205.
About the author Hamish Johnston is editor of physicsworld.com
Copyright Institute of Physics (the “Institute”) and IOP Publishing 2011
When Mount Tambora in Indonesia started being rocked by a steady stream of quakes, villagers fled and were reluctant to return, despite assurances of safety. People near Tambora are jittery because of the mountain's history: the April 1815 eruption left a crater seven miles wide and half a mile deep, spewing 400 million tons of sulfuric gases.
By Nasrullah Roa September 19, 2011 12:57PM
Bold farmers in Indonesia routinely ignore orders to evacuate the slopes of live volcanoes, but those living on Tambora took no chances when history's deadliest mountain rumbled ominously this month.
Villagers like Hasanuddin Sanusi have heard since they were young how the mountain they call home once blew apart in the largest eruption ever recorded -- an 1815 event widely forgotten outside their region -- killing 90,000 people and blackening skies on the other side of the globe.
So, the 45-year-old farmer didn't wait to hear what experts had to say when Mount Tambora started being rocked by a steady stream of quakes. He grabbed his wife and four young children, packed his belongings and raced down its quivering slopes.
"It was like a horror story, growing up," said Hasanuddin, who joined hundreds of others in refusing to return to their mountainside villages for several days despite assurances they were safe.
"A dragon sleeping inside the crater, that's what we thought. If we made him angry -- were disrespectful to nature, say -- he'd wake up spitting flames, destroying all of mankind."
The April 1815 eruption of Tambora left a crater 11 kilometers (7 miles) wide and 1 kilometer (half a mile) deep, spewing an estimated 400 million tons of sulfuric gases into the atmosphere and leading to "the year without summer" in the U.S. and Europe.
It was 10 times more powerful than Indonesia's much better-known Krakatoa blast of 1883 -- history's second deadliest. But it doesn't share the same international renown, because the only way news spread across the oceans at the time was by slowboat, said Tambora researcher Indyo Pratomo.
In contrast, Krakatoa's eruption occurred just as the telegraph became popular, turning it into the first truly global news event.
The reluctance of Hasanuddin and others to return to villages less than 10 kilometers (6 miles) from Tambora's crater sounds like simple good sense. But it runs contrary to common practice in the sprawling nation of 240 million -- home to more volcanoes than any other in the world.
Even as Merapi, Kelut and other famously active mountains shoot out towering pillars of hot ash, farmers cling to their fertile slopes, leaving only when soldiers load them into trucks at gunpoint. They return before it's safe to check on their livestock and crops.
Tambora is different.
People here are jittery because of the mountain's history -- and they're not used to feeling the earth move so violently beneath their feet. ...
Future Iceland Eruptions Could Be Deadly for Europe
Laki volcanic region, Iceland. (R.M.C. Lopes/NASA)
By Sid Perkins, ScienceNOW September 19, 2011 | 4:16 pm
What if one of the largest volcanic eruptions in recent history happened today? A new study suggests that a blast akin to one that devastated Iceland in the 1780s would waft noxious gases southeastward and kill tens of thousands of people in Europe. And in a modern world that is intimately connected by air traffic and international trade, economic activity across much of Europe, including the production and import of food, could plummet.
From June of 1783 until February of 1784, the Laki volcano in south-central Iceland erupted. Although the event didn’t produce large amounts of volcanic ash, it did spew an estimated 122 million metric tons of sulfur dioxide gas into the sky — a volume slightly higher than human industrial activity today produces in the course of a year, says Anja Schmidt, an atmospheric scientist at the University of Leeds in the United Kingdom.
Historical records suggest that in the 2 years after the Laki eruption, approximately 10,000 Icelanders died — about one-fifth of the population — along with nearly three-quarters of the island’s livestock. Parish records in England reveal that in the summer of 1783, when the event began, death rates were between 10 percent and 20 percent above normal. The Netherlands, Sweden, and Italy reported episodes of decreased visibility, respiratory difficulties, and increased mortality associated with the eruption. According to one study, an estimated 23,000 people died from exposure to the volcanic aerosols in Britain alone. But elsewhere in Europe, it’s difficult to separate deaths triggered by the air pollution from those caused by starvation or disease, which were prominent causes of death at the time.
To assess how such an eruption might affect the densely populated Europe of today, Schmidt and her colleagues plugged a few numbers into a computer simulation. They used weather models to estimate where sulfur dioxide emissions from an 8-month-long eruption that commenced in June would end up. They also estimated the resulting increases in the concentrations of airborne particles smaller than 2.5 micrometers across, the size of aerosols that are most easily drawn into human lungs and that cause cardiopulmonary distress. Then, they used modern medical data to estimate how many people those aerosols would kill.
In the first 3 months after the hypothetical eruption began, the average aerosol concentration over Europe would increase by 120 percent, the team reports online today in the Proceedings of the National Academy of Sciences. The number of days during the eruption in which aerosol concentrations exceed air-quality standards would rise to 74, when a normal period that length typically includes only 38. Not surprisingly, the air would become thickest with dangerous particles in areas downwind of the eruption, such as Iceland and northwestern Europe, where aerosol concentrations would more than triple. But aerosol concentrations in southern Europe would also increase dramatically, rising by 60 percent.
In the year after the hypothetical eruption commences, the increased air pollution swept from Iceland to Europe would cause massive amounts of heart and lung disease, killing an estimated 142,000 people. Fewer than half that number of Europeans die from seasonal flu each year.
At least four Laki-sized eruptions have occurred in Iceland in the past 1,150 years, Schmidt and her colleagues say. So the new figures are cause for concern.
The team “has done a good job of showing where volcanic aerosols would end up, and the human health response to such aerosols is well understood,” says Brian Toon, an atmospheric scientist at the University of Colorado, Boulder. “This is all very solid science.”
Icelandic volcanoes shut down European air traffic for more than a week in April 2010 and for several days in May of this year. But those eruptions are tiny compared with a Laki-sized eruption, which could ground airplanes for 6 months or more, says Alan Robock, an atmospheric scientist at Rutgers University in New Brunswick, New Jersey. Such an event would have a huge impact on crop yields and, by affecting shipping and air traffic, would also affect Europeans’ ability to import food, he notes. It could even have a dramatic effect on daily life, he says. “If there are sulfur dioxide clouds over Europe, people with respiratory problems can’t do much about it except stay indoors.”
This story provided by ScienceNOW, the daily online news service of the journal Science.
Small Glacial Outburst Flood from Spurr in Alaska ..with links..
By Erik Klemetti Email Author June 27, 2012 | 11:09 am |
The plume from the August 18, 1992 eruption of Alaska’s Spurr. The eruptive period started on June 27, 1992. Image by R.G. McGimsey, courtesy of AVO/USGS.
Brief note, just because I love coincidences like this:
Twenty years ago today (June 27), Mt. Spurr in Alaska produced one of the largest eruptions of the Aleutians in the past 50 years – a VEI 4 eruption that featured at 20 km / 65,000 foot plume. That eruption deposited 2 mm of ash as far at 270 km from the volcano. Over the next few months following the June 27 eruption, a number of smaller eruptions followed before the volcano went quiet again in September 1992. You can check out a nice “guided tour” of images from the 1992 volcanic crisis at Spurr.
Why do I bring this up? Well, Spurr must have felt festive as the volcano had a “minor increase in seismicity” that coincided with a small glacial outburst flood on Monday (June 25). The increase in earthquake activity was brief – by the morning of the 26th, the seismicity was over. Now, this doesn’t mean the volcano is ramping up for anything. Spurr is snow/ice-covered, so slow melting under the ice could pool water until it is dramatically released with an ice or sediment dam holding it back releases. The Alaska Volcano Observatory mentions that Spurr had a similar event in June 1993 as well.
However, it is a good way to remind us that Alaskan volcanoes are always a threat to produce significant eruptions. Be sure to check out AVO’s Spurr page to see the webcam and webicorders for the volcano.
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