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aamukherjee A Slice of Entropie -
alchymista Alchymista -
crownedrose Fading Like A Dead Star -
expose-the-light Quarks to Quasars -
ikenbot CWL -
abluegirl A Blue Girl -
perscientiamlibertas A Matter of the Most Pleasant Fraternal Confidence
How to Measure the Explosive Power of Volcanoes
By George Dvorsky
Scientists have scales to measure the strength of natural phenomena like earthquakes and hurricanes. But what about the eruptive power of volcanoes? For that, geologists use the Volcanic Explosivity Index. Here’s how it works.
The Volcanic Explosivity Index (VEI) was first proposed in 1982 by Christopher Newhall of the U.S. Geological Survey and Stephen Self of the University of Hawaii. Their intention was to develop a scale to estimate the explosive magnitude of historical volcanoes.
To that end, they came up with an incrementing logarithmic scale to measure the magnitude of past explosive eruptions, which Newhall described as a “semiquantitative compromise between poor data and the need in various disciplines to evaluate the record of past volcanism.”
But establishing the parameters for a useful scale proved easier said than done. Unlike earthquakes or hurricanes, there are different types of volcanoes, and they produce different products, like massive plumes of ejected rock and ash, or molten lava flows.
Moreover, and as scientists later learned, volcanoes also churn-out varying degrees of sulfur dioxide at rates irrespective of eruptive power. It’s for that reason that the VEI had to be rejected as a way to measure an eruption’s potential impact on the climate. Today, it’s used exclusively to measure the explosive power of both historic and new eruptions.
How the Scale Works
Similar to the Richter scale, the VEI uses a numerical index ranging from 0 to 8. Each increment represents an 10-fold increase in explosivity. Factors that are taken into account include the volume of pyroclastic material (including ashfall, pyroclastic flows, and other ejecta), the height of the eruption, duration in hours, and a number of other qualitative measurements.
So, given that the scale is primarily driven by the volume ejected, it goes like this:
- VEI 0: eruptions that produce less than 0.0001 cubic kilometer of ejecta (small events that typically produce flowing lava, which is called an effusive eruption)
- VEI 1: eruptions that produce between 0.0001 and 0.001 cubic kilometers of ejecta
- VEI 2: eruptions that produce between 0.001 and 0.01 cubic kilometers of ejecta
- VEI 3: eruptions that produce between 0.01 and 0.1 cubic kilometers of ejecta
And so on until we get to VEI 8.
So, a VEI 5 is roughly 100 times more explosive than a VEI 3, and a VEI 8 is a million times more powerful than a VEI 2. Sometimes a + symbol is added to account for the wide degree of variation between each number in the scale.
The VEI doesn’t go past 8, but that doesn’t mean a VEI 9 isn’t impossible. Scientists may still uncover evidence of such an event buried somewhere in the geological record.
abluegirl
Yellowstone’s Volcanic Plumbing More Extensive Than Believed
by Becky Oskin
Yellowstone’s underground volcanic plumbing is bigger and better connected than scientists thought, researchers reported here today (April 17, 2013) at the Seismological Society of America’s annual meeting.
“We are getting a much better understanding of the volcanic system of Yellowstone,” said Jamie Farrell, a seismology graduate student at the University of Utah. “The magma reservoir is at least 50 percent larger than previously imaged.”
Knowing the volume of molten magma beneath Yellowstone is important for estimating the size of future eruptions.
Geologists believe Yellowstone sits over a hotspot, a plume of superheated rock rising from Earth’s mantle. As North America slowly drifted over the hotspot, the Yellowstone plume punched through the continent’s crust, leaving a bread-crumb-like trail of calderas created by massive volcanic eruptions along Idaho’s Snake River Plain, leading straight to Yellowstone.
The last caldera eruption was 640,000 years ago. Smaller eruptions occurred in between and after the big blasts, most recently about 70,000 years ago…
(read more: Lives Science) (image: National Park Service)
From Smithsonian Photo Of The Day; April 13, 2013:
Lava flow from the Kīlauea Volcano on the island of Hawai’i flows into the sea.
Photo and caption by Varina Patel (Twinsburg, OH); Photographed December, 2012
(via wigmund)
Iceland volcano ash cloud triggers plankton bloom
The 2010 Icelandic volcanic eruption, which disrupted European flights, also had a “significant but short-lived” impact on ocean life, a study shows.
Ash from the Eyjafjallajokull volcano deposited dissolved iron into the North Atlantic, triggering a plankton bloom.
The authors said it was good fortune they were at sea at the time as it provided a unique opportunity to sample the ocean during a volcanic eruption.
The findings appear in the Geophysical Research Letters journal.
In April 2010, the eruption sent an ash plume several kilometres into the atmosphere, causing ash to deposited across up to 570,000 sq km of the North Atlantic Ocean.
The five-week volcanic activity was still ongoing when a team of researchers arrived in the Iceland Basin region aboard a research vessel.
“Our study was unique in the sense that we were the first to undertake sampling at sea of volcanic ash deposition and the chemical and biological effects in the surface ocean,” explained lead author Eric Achterberg from the National Oceanography Centre Southampton, UK.
“In addition, we were able to sample the ocean region again a few months after the eruption and observe the changes since the eruption.
“The opportunity to sample during the eruption and also a couple of months after the event allowed us to obtain a unique insight into the effects of the ash deposition on the biology and chemistry of the Iceland Basin.”
Three years earlier, the team had shown that the production of phytoplankton - microscopic plants that form a key component of marine food chains - was limited by the availability of dissolved iron, which was essential for the tiny plants’ growth.
Prof Achterberg told BBC News what the in-situ team was able to record: “Biological experiments showed that the volcanic ash released the iron that stimulated phytoplankton growth.
“The effect of the volcanic ash inputs were nevertheless short-lived as the extra iron supplied by the volcano resulted in rapid biological nitrate removal, thereby causing nitrogen limitation of the phytoplankton population.”
So while the additional dissolved iron triggered an earlier-than-usual phytoplankton bloom, as the metal triggered growth in a greater number of phytoplankton cells, the bloom was only 15-20% larger than normal because the growth was limited by the amount of available nitrogen, another vital ingredient required for the organisms to develop.
As well as playing an important role in food chains, phytoplankton also absorb carbon dioxide from the atmosphere.
Oceans are considered to be one of the planet major players in the global carbon cycle, but the carbon uptake in the region where the eruption occurred has limited capacity.
“The high latitude North Atlantic Ocean is a globally important ocean region, as it is a sink for atmospheric carbon dioxide and an area where deep water formation takes place,” Prof Achterberg observed.
“A limit to the availability of iron in this region means that the ocean is less efficient in its uptake of atmospheric carbon dioxide.”
However during the bloom triggered by the ash deposits from the eruption, the team recorded that it was a shortage of nitrogen that limited the size of the phytoplankton bloom and - as a result - the volume of carbon dioxide uptake.
Prof Achterberg concluded: “The 2010 Eyjafjallajokull eruption therefore resulted in a significant but short lived perturbation to the biogeochemistry of the Iceland Basin.”
Iceland Volcano Eruption Fueled Ocean Blooms
by Charles Q. Choi
The explosive volcanic eruption Iceland saw in 2010 may have disrupted life in the air above Europe, but it apparently enriched life in the Atlantic Ocean, researchers say.
After nearly two centuries of dormancy, the volcano Eyjafjallajökull (AYA-feeyapla-yurkul) erupted many times over the course of 10 weeks three years ago. These outbursts spewed a giant plume of ash that spread unusually far and stayed for an oddly long time in the atmosphere,forcing widespread flight cancellations for days.
Serendipitously, marine biogeochemist Eric Achterberg at the University of Southampton in England and his colleagues were taking part in a series of research cruises in the Iceland Basin region of the North Atlantic Ocean both during and after the eruption. These three cruises allowed the researchers to measure iron concentrations at the ocean’s surface before, during and after the eruption in areas directly influenced by the plume of iron-rich ash…
(read more: OurAmazingPlanet)
(photo: Jeff Schmaltz, MODIS Rapid Response Team @ NASA GSFC)
Happy Burst-day Hawaii Volcano Hotspot!
The Hawaiian volcano Kilauea celebrates thirty years of continuous activity this year. One Kilauea hotspot, the Halema‘uma‘u crater, will mark its fifth anniversary of constant eruption on March 19. Happy burst-day!
The U.S. Geological Survey will commemorate Halema‘uma‘u’s big day with special presentations on the observation deck overlooking the fuming lava pit in the crater. Although the lava cannot be safely viewed from the observation deck, at night a glow emanates from the hellish pit, illuminating the plume of foul-smelling smoke rising from the Earth’s depths.
“Where else in the world can you park your car, and walk just a few feet to behold the spectacle of one of the world’s most active volcanoes?” said Park Superintendent Cindy Orlando in a press release.
Halema‘uma‘u exploded and opened a 115-foot wide hole on the volcano’s summit at 2:58 a.m. on March 19, 2008. The eruption revealed a roiling lake of lava within the volcano.
The Halema‘uma‘u crater belches out an average 800-1,200 tonnes of dangerous sulfur dioxide gas everyday. That’s a decline from when the crater started in 2008, but still more than enough to create hazardous conditions around the volcano’s rim and cause air pollution downwind.
Gas emissions may have dropped off since 2008, but the vent itself has increased to approximately 520 feet by 700 feet, equivalent to the area of 21 Olympic-sized swimming pools.
Within the crater, a churning lake of fiery foam rises and falls with changes in subsurface magma pressure. In December 2012, the lave came within 72 feet of overflowing the rim.
ikenbot
February 19, 2013 Eruption of Mount Etna
Mount Etna, on the island of Sicily, Italy, has long been one of Europe’s most active volcanoes — eruptions have been observed here for approximately 3,500 years. The most recent series of eruptions were initiated during the early morning hours of February 19, 2013, when glowing fountains of lava erupted from Mount Etna’s southeast crater.
The Atlantic has a stunning gallery of the year 2012 in volcanic activity that you really want to check out.
Ever since our planet formed from a cloud of condensed stellar dust, the dense heat of our interior has created a molten core surrounded by a thin candy shell of solid rock. That shell continues to evolve, leaking magma via cracks in its moving surface, via events both quiet and violent.
Such is the continual evolution of our planet. It’s a beautiful process, assuming you’re looking at it in a photograph, rather than while running in fear from the bottom of the mountain where it’s occurring.
Red Rock, Green Water by OxWearingSocks on Flickr.
The Emerald lakes are explosion craters on the massif at Mount Tongariro, a compound volcano on the North Island of New Zealand.
(via ikenbot)
Shiprock gives the impression of having been volcanically thrust out from the sands of the Mancos desert, but this isn’t the case. Shiprock is indeed a volcano but of a class called a “diatreme”, having formed explosively from gas-charged magma escaping at great velocity. It possessed a crater at the surface called a “maar”, but erosion has long since removed it along with much of the sedimentary strata through which it erupted.
A long exposure image captured the rotating sky above Karapinar volcanic field located in central Anatolia, Turkey.
Odd Sea Creatures Found at Volcanoes, Canyons
1. Crown Jellyfish
Found in a canyon about 5,000 feet (1,500 meters) deep, this unidentified jellyfish is likely a type of Atolla, a genus of crown jellyfish that dwells only at depth. Photograph courtesy NIWA
2. ”Mickey Mouse” Squid
Commonly called a “mickey mouse” squid, this small sepiolid was discovered about 3,000 feet (900 meters) deep on a canyon wall. Photograph courtesy NIWA
3. Cup Coral
Unlike reef-building corals that form giant colonies, cup corals—such as thisStephanocyathus platypus, found 3,200 feet (1,000 meters) down—live solitary lives in their cuplike limestone exterior skeletons, according to Monterey Bay Aquarium. Photograph courtesy NIWA
4. Honeycomb Glass Sponge
With a silicon-based skeleton, a new species of “beautiful and fragile” honeycomb glass sponge of the Farrea genus was found on a seamount at 3,100 feet (950 meters) deep—and it wasn’t alone. Photograph courtesy NIWA
5. Tonguefish
The Tangaroa Seamount offered up a new species of tonguefish in theSymphurus genus (pictured). Photograph courtesy NIWA
6. Coral, With a Side of Crab
Pictured with a crab emerging from its middle, this likely new species ofEpizoanthus coral has polyps that, when extended, resemble its close relative the sea anemone. Photograph courtesy NIWA
7. Sea Slug
A potential new species of sea slug was caught in a canyon at depths of 4,100 feet (1,250 meters). Photograph courtesy NIWA
8. Snake Stars
Yellowish snake stars of the species Asteroschema bidwillae were caught on an undersea peak called Tangaroa Seamount at a depth of 4,000 feet (1,220 meters). Photograph courtesy NIWA
9. Uroptychus Squat Lobster
Found between depths of 2,130 feet (650 meters) and 4,600 feet (1,400 meters), this squat lobster of the Uroptychus genus isn’t the first known specimen of its kind, but its species hasn’t yet been formally recognized. Photograph courtesy NIWA
Jupiter Moon Io’s Volcanoes Revealed in New Map
A new map of Jupiter’s oddly active moon Io has revealed the location of the moon’s many erupting volcanoes, raising as many questions about the enigmatic satellite as it answers.
The map is the most comprehensive ever compiled of Io’s hundreds of active volcanoes, researchers said. It also suggests a complex, multi-layer source for the moon’s huge stores of internal thermal energy, which may come as a surprise to some astronomers.
“The fascinating thing about the distribution of the heat flow is that it is not in keeping with the current preferred model of tidal heating of Io at relatively shallow depths,” co-author Ashley Davies, of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. “Instead, the main thermal emission occurs about 40 degrees eastward of its expected positions.”
Spouting fire and noxious gases, volcanoes have alternatively inspired and frightened people since the dawn of time. Now, thanks to the various Earth-observing satellites of NASA, we can see epic eruptions as never before.
9 images of volcanoes as seen from space
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