Tag: volcanoes

Active lava flows found on Venus

9:10 am

volcanoes on Venus

Cool image time! Using archival data from Venus Express, scientists have identified several spots on Venus where it appears there are active lava flows.

Using a near-infrared channel of the spacecraft’s Venus Monitoring Camera (VMC) to map thermal emission from the surface through a transparent spectral window in the planet’s atmosphere, an international team of planetary scientists has spotted localised changes in surface brightness between images taken only a few days apart. “We have now seen several events where a spot on the surface suddenly gets much hotter, and then cools down again,” says Eugene Shalygin from the Max Planck Institute for Solar System Research (MPS) in Germany, and lead author of the paper reporting the results in Geophysical Research Letters this month. “These four ‘hotspots’ are located in what are known from radar imagery to be tectonic rift zones, but this is the first time we have detected that they are hot and changing in temperature from day to day. It is the most tantalising evidence yet for active volcanism.”

The hotspots are found along the Ganiki Chasma rift zone close to the volcanoes Ozza Mons and Maat Mons. Rift zones are results of fracturing of the surface, which is often associated with upwelling of magma below the crust. This process can bring hot material to the surface, where it may be released through fractures as a lava flow.

There have been hints of volcanic activity on Venus since Pioneer Venus Orbiter first circled the planet from 1978 to 1992. This appears to be the first solid evidence of it.

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Seismic data of Yellowstone has found a bigger second magma chamber

9:52 am

Geologists have mapped the existence of a second deeper and larger magma chamber under Yellowstone National Park.

Scientists had already known about a plume, which brings molten rock up from deep in the mantle to a region about 60 kilometers below the surface. And they had also imaged a shallow magma chamber about 10 kilometers below the surface, containing about 10,000 cubic kilometers of molten material. But now they have found a deeper one, 4.5 times larger, that sits between 20 and 50 kilometers below the surface. “They found the missing link between the mantle plume and the shallow magma chamber,” says Peter Cervelli, a geophysicist in Anchorage, Alaska, who works at the U.S. Geological Survey’s Yellowstone Volcano Observatory.

The discovery does not, on its own, increase the chance of an eruption, which is driven by an emptying of the shallow chamber. The last major eruption was 640,000 years ago, and today the threat of earthquakes is far more likely. But the deeper chamber does mean that the shallow chamber can be replenished again and again. “Knowing that you have this additional reservoir tells you you could have a much bigger volume erupt over a relatively short time scale,” says co-author Victor Tsai, a geophysicist at the California Institute of Technology in Pasadena. The discovery, reported online today in Science, also confirms a long-suspected model for some volcanoes, in which a deep chamber of melted basalt, a dense iron- and magnesium-rich rock, feeds a shallower chamber containing a melted, lighter silicon-rich rock called a rhyolite.

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New data says volcanoes, not asteroids, killed dinosaurs

1:38 pm

The uncertainty of science: A careful updating of the geological timeline has strengthened the link between the dinosaur extinction 66 million years ago and a major volcanic event at that time.

A primeval volcanic range in western India known as the Deccan Traps, which were once three times larger than France, began its main phase of eruptions roughly 250,000 years before the Cretaceous-Paleogene, or K-Pg, extinction event, the researchers report in the journal Science. For the next 750,000 years, the volcanoes unleashed more than 1.1 million cubic kilometers (264,000 cubic miles) of lava. The main phase of eruptions comprised about 80-90 percent of the total volume of the Deccan Traps’ lava flow and followed a substantially weaker first phase that began about 1 million years earlier.

The results support the idea that the Deccan Traps played a role in the K-Pg extinction, and challenge the dominant theory that a meteorite impact near present-day Chicxulub, Mexico, was the sole cause of the extinction. The researchers suggest that the Deccan Traps eruptions and the Chicxulub impact need to be considered together when studying and modeling the K-Pg extinction event.

The general public might not know it, but the only ones in the field of dinosaur research that have said the asteroid was the sole cause of the extinction have been planetary scientists.

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Mapping the inside of Mt St. Helens

9:37 am

A new array of seismometers, combined with a series of planned explosions, will be used to map the interior of the Mt. St. Helens volcano to a depth of eighty kilometers or fifty miles.

To get the job done, starting next week roughly 65 people will fan out across the mountain to deploy 3,500 small seismometers along roads and back-country trails. They will drill 24 holes some 25 metres deep, drop in industrial explosives used for quarrying, and refill the holes (see ‘Under the dome’). The plan is to detonate the explosives in separate shots over four nights. Each blast will shake the ground as much as a magnitude-2 earthquake.

Results from the active blasts will be combined with the passive seismic part of the experiment, which is already under way: 70 larger seis­mometers around the mountain are measuring how long waves from natural earthquakes take to travel through the ground. Their data can be used to probe as far as 80 kilo­metres down, says Vidale.

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Scientists think they have detected active volcanoes on Venus.

3:12 pm

Scientists think they have detected active volcanoes on Venus.

We should hear more about this story in the next couple of days, after the scientists give their presentation at a science conference today. Note too that this result would only confirm other data, such as the fluctuating levels of sulfur in Venus’s atmosphere, that have suggested active volcanoes hidden under that planet’s thick cloud cover.

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The geological history of Venus: What’s known, not known, and unknown.

11:48 am

The geological history of Venus: What’s known, not known, and unknown.

This is a very clearly written overview by James Head, one of the world’s preeminent planetary geologists, of what has been learned about the geology of Earth’s sister planet, the planet of a million volcanoes. Key quote:

Many features on Venus (folded mountain belts, rift zones, tesserae) were like Earth, but there were few signs of Earth-like plate tectonics, so that Venus seemed to have a single lithospheric plate that was losing heat conductively and advectively. But the cratering record presented a conundrum. First, the average age of the surface was <20% of the total age of the planet, and second, the average was not a combination of very old and very young surfaces, such as Earth’s continents and ocean basins. Third, the lack of variability in crater density, and of a spectrum of crater degradation, meant that all geological units might be about the same age. This implied that the observed surface of Venus must have been produced in the past hundreds of millions of years, possibly catastrophically, with very little volcanic or tectonic resurfacing since then! Suddenly, Venus was not like Earth, nor like the Moon, Mars, or Mercury.

Some scientists even believe that Venus was essentially resurfaced in a massive volcanic event about a half billion years ago. Others disagree. Meanwhile, the European probe Venus Express has gotten hints that volcanic activity is still going on.

As Head concludes, it has been 20 years since the last spacecraft arrived at Venus to do geological research. It is time to return.

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Geologists have determined that the magma reservoir under Yellowstone is much bigger than previously thought.

9:25 am

The uncertainty of science: Geologists have determined that the magma reservoir under Yellowstone is much bigger than previously thought.

Jamie Farrell, a postdoctoral researcher at the University of Utah, mapped the underlying magma reservoir by analysing data from more than 4,500 earthquakes. Seismic waves travel more slowly through molten rock than through solid rock, and seismometers can detect those changes.

The images show that the reservoir resembles a 4,000-cubic-kilometre underground sponge, with 6–8% of it filled with molten rock. It underlies most of the Yellowstone caldera and extends a little beyond it to the northeast.

The geologists also noted that the threat from a huge volcanic eruption is less of a concern than that of earthquakes.

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Changes in the levels of sulphur dioxide since Venus Express arrived in orbit around Venus in 2006 now suggest strongly that the spacecraft has detected volcanic activity on the planet.

7:46 am

Changes in the levels of sulphur dioxide (SO2) since Venus Express arrived in orbit around Venus in 2006 now suggest strongly that the spacecraft has detected volcanic activity on the planet.

The SPICAV data show that the concentration of SO2 above the main cloud deck increased slightly to about 1000 parts per billion by volume (ppbv) between 2006 and 2007, but then steadily decreased over the next five years, reaching only 100 ppbv by 2012. This is very reminiscent of a pattern observed by Pioneer Venus during the 1980s, the only other multi-year dataset of SO2 measurements.

One of best explanations for these changes is a volcanic eruption back in 2006, which would have inserted a great deal of SO2 into the upper atmosphere. Since then, ultraviolet radiation from the sun has steadily destroyed it.

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The discovery of volcanoes on Io

12:39 pm

discovery image

On March 8, 1979, as Voyager 1 was speeding away from Jupiter after its historic flyby of the gas giant three days earlier, it looked back at the planet and took some navigational images. Linda Morabito, one of the engineers in charge of using these navigational images to make sure the spacecraft was on its planned course, took one look at the image on the right, an overexposed image of the moon Io, and decided that it had captured something very unusual. On the limb of the moon was this strange shape that at first glance looked like another moon partly hidden behind Io. She and her fellow engineers immediately realized that this was not possible, and that the object was probably a plume coming up from the surface of Io. To their glee, they had taken the first image of an eruption of active volcano on another world!

Today, on the astro-ph preprint website, Morabito has published a minute-by-minute account of that discovery. It makes for fascinating reading, partly because the discovery was so exciting and unique, partly because it illustrated starkly the human nature of science research, and partly because of the amazing circumstances of that discovery. Only one week before, scientists has predicted active volcanism on Io in a paper published in the journal Science. To quote her abstract:
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Mars’ clay minerals might have been formed by volcanic processes, not standing liquid water as generally believed.

9:37 am

The uncertainty of science: Mars’ clay minerals might have been formed by volcanic processes, not standing liquid water as generally believed, according to a new study.

Data collected by orbiting spacecraft show Mars’ clay minerals may instead trace their origin to water-rich volcanic magma, similar to how clays formed on the Mururoa atoll in French Polynesia and in the Parana basin in Brazil. That process doesn’t need standing bodies of liquid water. “The infrared spectra we got in the lab (on Mururoa clays) using a reflected beam are astonishingly similar to that obtained on Mars by the orbiters,” lead researcher Alain Meunier, with the University of Poitiers in France, wrote in an email to Discovery News. The team also points out that some of the Mars meteorites recovered on Earth do not have a chemistry history that supports standing liquid water.

If correct, this alternative explanation would mean that Mars was not that wet in the past, and would have been far less likely of ever having sustained life.

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In a paper published today in Geophysical Research Letters, researchers studying an icecore drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century Little Ice Age in the southern hemisphere.

9:07 am

In a paper published today in Geophysical Research Letters, researchers studying an ice core drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century’s Little Ice Age in the southern hemisphere. From the abstract:

The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100-year average. … This result is consistent with the idea that the [Little Ice Age] was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses.

In an effort to emphasis human-caused global warming and eliminate any evidence of climate change caused by other factors, many global warming scientists have argued that the Little Ice Age was not a global event but merely a cooling in Europe. This data proves them wrong. The global climate has varied significantly in the recent past, and not because of human behavior. Other factors, such as fluctuations in the solar cycle, must be considered more seriously for scientists to obtain a better understanding of the Earth’s climate.

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The explosive Kilauea volcano

10:41 am

At a press conference just completed at the American Geophysical Union meeting in San Francisco, geologist Don Swanson of the U.S. Geological Hawaiian Volcano Observatory revealed that the Kilauea volcano on the Big Island of Hawaii has been in an explosive mode about sixty percent of the time in the past 2500 years. “Kilauea is not the gentle volcano that most people assume,” noted Swanson.
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The journal Science finally admits things have not gotten warmer in the past decade

8:52 pm

The journal Science finally admits things have not gotten warmer in the past decade.

The explanation provided, that recent volcanic eruptions cooled a warming earth, might be true, though the conclusions are based not so much on data but on climate computer models, a fact that leaves me somewhat skeptical. Nonetheless, what is significant to me about this article is that Science — which has been decidedly in the global warming political camp for years and has frequently lambasted scientists who suggested the climate’s warming has slowed or even stopped in the past decade — has now been forced to admit that the warming has stopped. That they feel compelled to push the global warming threat in the same sentence only reveals their continuing scientific bias.

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