Underwater Times: Researchers: Deep-Sea Volcanoes Don't Just Produce Lava Flows, They Also Explode!
MONTREAL, Quebec -- McGill geology researchers' discovery of high concentrations of CO2 at mid-ocean ridges confirms explosive nature of certain volcanic eruptions
Between 75 and 80 per cent of all volcanic activity on Earth takes place at deep-sea, mid-ocean ridges. Most of these volcanoes produce effusive lava flows rather than explosive eruptions, both because the levels of magmatic gas (which fuel the explosions and are made up of a variety of components, including, most importantly CO2) tend to be low, and because the åvolcanoes are under a lot of pressure from the surrounding water.
Over about the last 10 years however, geologists have nevertheless speculated, based on the presence of volcanic ash in certain sites, that explosive eruptions can also occur in deep-sea volcanoes.
But no one has been able to prove it until now.
By using an ion microprobe, Christoph Helo, a PhD student in McGill's Department of Earth and Planetary Sciences, has now discovered very high concentrations of CO2 in droplets of magma trapped within crystals recovered from volcanic ash deposits on Axial Volcano on the Juan de Fuca Ridge, off the coast of Oregon.
These entrapped droplets represent the state of the magma prior to eruption. As a result, Helo and fellow researchers from McGill, the Monterey Bay Aquarium Research Institute, and the Woods Hole Oceanographic Institution, have been able to prove that explosive eruptions can indeed occur in deep-sea volcanoes. Their work also shows that the release of CO2 from the deeper mantle to the Earth's atmosphere, at least in certain parts of mid-ocean ridges, is much higher than had previously been imagined.
Given that mid-ocean ridges constitute the largest volcanic system on Earth, this discovery has important implications for the global carbon cycle which have yet to be explored.
Tuesday, March 29, 2011
Friday, March 25, 2011
Another Volcano Glossary - the As
Aa - Hawaiian word used to describe a lava flow whose surface is broken into angular, jagged fragments.
Agglutinate - A volcanic deposit formed by the accumulation of flattened and welded fragments, typically derived from showers of still-molten rock particles ejected in magma fountains. The liquid fragments may accumulate to form a stream of lava.
Andesite - A lava of intermediate composition, usually light gray or brown in color. Andesite has a silica content ranging from about 54 to 62 percent.
Andesite line - An imaginary line drawn around the boundary of the Pacific Ocean basin, seperating continental and oceanic lava rocks according to their chemical composition. On the Pacific side of the line lavas are basaltic. On the continental side, lavas with a higher silica content, such as andesites, commonly occur.
Ar - the element argon
Ash - fine particles of pulverized blown from a volcano. Measuring less than about 0.1 in diamer, ash may be either solid or molten when first erupted.
By far the most common variety is vitric ash, glassy particles formed by gas bubbles bursting through liquid magma.
Lithic ash is formed of older rock pulverized during an explosive eruption, while in:
crystal ash each grain is composed of a single crystal or group of crystals with only traces of glass adhering to them. Many volcanic ash deposits contain mixtures of all three kinds in various proportions.
Ash fall -a rain of ash from an eruption cloud
Ash flow - An avalanche of hot volcanic ash and gases that can travel great distances at high speeds from an erupting vent. Large-volume ash flow deposits commonly solidify to form Ignimbrites. (Also called a pyroclastic flow).
Asthenosphere - A zone of the earth's outer shell beneath the lithosphere. Of undetermined thickness, this is a region of weakness where plastic movements occur.
Bibliography
Fire Mountains of the West: The Cascade and Mono Lake Volcanoes, Stephen L. Harris. Mountain Press Publishing Company. 1988
Agglutinate - A volcanic deposit formed by the accumulation of flattened and welded fragments, typically derived from showers of still-molten rock particles ejected in magma fountains. The liquid fragments may accumulate to form a stream of lava.
Andesite - A lava of intermediate composition, usually light gray or brown in color. Andesite has a silica content ranging from about 54 to 62 percent.
Andesite line - An imaginary line drawn around the boundary of the Pacific Ocean basin, seperating continental and oceanic lava rocks according to their chemical composition. On the Pacific side of the line lavas are basaltic. On the continental side, lavas with a higher silica content, such as andesites, commonly occur.
Ar - the element argon
Ash - fine particles of pulverized blown from a volcano. Measuring less than about 0.1 in diamer, ash may be either solid or molten when first erupted.
By far the most common variety is vitric ash, glassy particles formed by gas bubbles bursting through liquid magma.
Lithic ash is formed of older rock pulverized during an explosive eruption, while in:
crystal ash each grain is composed of a single crystal or group of crystals with only traces of glass adhering to them. Many volcanic ash deposits contain mixtures of all three kinds in various proportions.
Ash fall -a rain of ash from an eruption cloud
Ash flow - An avalanche of hot volcanic ash and gases that can travel great distances at high speeds from an erupting vent. Large-volume ash flow deposits commonly solidify to form Ignimbrites. (Also called a pyroclastic flow).
Asthenosphere - A zone of the earth's outer shell beneath the lithosphere. Of undetermined thickness, this is a region of weakness where plastic movements occur.
Bibliography
Fire Mountains of the West: The Cascade and Mono Lake Volcanoes, Stephen L. Harris. Mountain Press Publishing Company. 1988
Thursday, March 24, 2011
Volcano-sparked fire threatens Hawaii wildlife area
CNN: Volcano-sparked fire threatens Hawaii wildlife area
A fire ignited by lava from the Kilauea Volcano on Hawaii's Big Island is threatening what a National Park Service spokesman calls "a living laboratory of Hawaiian plants and animals," the Star-Advertiser in Honolulu reports.
The fire, which began on March 5, has burned 100 acres of a 2,750-acre special ecological area in a lowland rain forest, according to the Park Service.
Among the creatures in the area are happy face spiders, carnivorous caterpillars and the endangered Hawaiian bat, the newspaper said, citing Park Service fire information spokesman Gary Wuchner.
"It best represents what Hawaii was, and is a seed source for plants and refuge for birds," Hawaii Volcanoes National Park spokeswoman Mardi Lane told the Star-Advertiser.
Forty Park Service firefighters from Hawaii and western mainland states are battling the fire, according to the report.
A fire ignited by lava from the Kilauea Volcano on Hawaii's Big Island is threatening what a National Park Service spokesman calls "a living laboratory of Hawaiian plants and animals," the Star-Advertiser in Honolulu reports.
The fire, which began on March 5, has burned 100 acres of a 2,750-acre special ecological area in a lowland rain forest, according to the Park Service.
Among the creatures in the area are happy face spiders, carnivorous caterpillars and the endangered Hawaiian bat, the newspaper said, citing Park Service fire information spokesman Gary Wuchner.
"It best represents what Hawaii was, and is a seed source for plants and refuge for birds," Hawaii Volcanoes National Park spokeswoman Mardi Lane told the Star-Advertiser.
Forty Park Service firefighters from Hawaii and western mainland states are battling the fire, according to the report.
Monday, March 21, 2011
Rain aids battle against 1,800-acre volcano blaze
Star Advertiser (Honolulu): Rain aids battle against 1,800-acre volcano blaze
Hawaii Volcanoes National Park firefighters continue to map and monitor the Napau Fire located on the east rift of Kilauea Volcano, which has burned more than 1,800 acres since it was first triggered by the March 5 Kamoamoa fissure eruption.
Two days of rain have helped to slow the fire's spread, and fire crews have used the time to develop safety zones in cool areas within the fire perimeter and monitor vegetation that can act as fuel for the blaze.
According to Napau Fire information officer Gary Wuscher, pockets of high heat remain on the front and flanks of the fire.
Wuscher has said that park firefighters are waiting for more favorable conditions before engaging the fire for safety and practicality considerations.
In the meantime, crews have been busy with various precautionary and strategic tasks.
Off Chain of Craters Road near the Pali, crews installed a temporary water storage tank, which will allow firefighters to draw water continuously without having to move their fire engine back and forth.
Crews were also able to cut back brush to protect sensitive monitoring equipment used by the U.S. Geological Survey to track seismic activity.
Hawaii Volcanoes National Park firefighters continue to map and monitor the Napau Fire located on the east rift of Kilauea Volcano, which has burned more than 1,800 acres since it was first triggered by the March 5 Kamoamoa fissure eruption.
Two days of rain have helped to slow the fire's spread, and fire crews have used the time to develop safety zones in cool areas within the fire perimeter and monitor vegetation that can act as fuel for the blaze.
According to Napau Fire information officer Gary Wuscher, pockets of high heat remain on the front and flanks of the fire.
Wuscher has said that park firefighters are waiting for more favorable conditions before engaging the fire for safety and practicality considerations.
In the meantime, crews have been busy with various precautionary and strategic tasks.
Off Chain of Craters Road near the Pali, crews installed a temporary water storage tank, which will allow firefighters to draw water continuously without having to move their fire engine back and forth.
Crews were also able to cut back brush to protect sensitive monitoring equipment used by the U.S. Geological Survey to track seismic activity.
Volcanoes' role in origins of life found after 50 years lost in a lab
The Independent (UK): Volcanoes' role in origins of life found after 50 years lost in a lab
An experiment carried out more than 50 years ago has revealed that volcanoes may have played a crucial role in the formation of the first organic building blocks of life, which led to the first replicating lifeforms on earth about 4.5 billion years ago.
Laboratory samples left over from a 1958 experiment in an American university have revealed, with the help of modern analytical techniques, that scientists had unwittingly discovered that gases given off by volcanoes can be used to make the vital sulphur-containing amino acids of proteins. The discovery is further vindication of the pioneering experiments of Stanley Miller, who as a young graduate student demonstrated that a "primordial soup" of water and a few simple gases such as ammonia and hydrogen can, with the help of electricity discharges to simulate lightning, produce the more complex organic molecules of life.
Dr Miller, who died in 2007, conducted many of his experiments at the University of California, San Diego, and received worldwide recognition for his earliest work in 1953.
But there was one set of experiments carried out five years later with the volcanic gas, hydrogen sulphide, that he seemed to have put to one side without fully realising what he had found. Jeffrey Bada, a former student of Dr Miller's who is now a Professor of Marine Chemistry at Scripps Institution of Oceanography in San Diego, discovered the residue samples from the original 1958 experiment and analysed the contents using highly sensitive chemical techniques that were not available 50 years ago. The study, published in the journal Proceedings of the National Academy of Sciences, revealed that Dr Miller was the first scientist to synthesise important sulphur-containing amino acids in this simulation of the environment of early earth. In total, Professor Bada's team found 23 amino acids and four similar compounds known as amines in Dr Miller's discarded samples, including seven substances containing sulphur.
"This experiment marks the first synthesis of sulphur amino acids from spark-discharge experiments designed to imitate primordial environments. The relative yield of some amino acids... are the highest ever found in a spark-discharge experiment," the scientists write. Professor Bada said that Dr Miller's team was only able to use a relatively primitive technique called paper chromatography to detect the presence of organic molecules.
The creation of sulphur-containing amino acids using similar techniques was eventually confirmed in the 1970s, including in Dr Miller's lab. "Unbeknownst to him, he'd already done it in 1958," Professor Bada said.
An experiment carried out more than 50 years ago has revealed that volcanoes may have played a crucial role in the formation of the first organic building blocks of life, which led to the first replicating lifeforms on earth about 4.5 billion years ago.
Laboratory samples left over from a 1958 experiment in an American university have revealed, with the help of modern analytical techniques, that scientists had unwittingly discovered that gases given off by volcanoes can be used to make the vital sulphur-containing amino acids of proteins. The discovery is further vindication of the pioneering experiments of Stanley Miller, who as a young graduate student demonstrated that a "primordial soup" of water and a few simple gases such as ammonia and hydrogen can, with the help of electricity discharges to simulate lightning, produce the more complex organic molecules of life.
Dr Miller, who died in 2007, conducted many of his experiments at the University of California, San Diego, and received worldwide recognition for his earliest work in 1953.
But there was one set of experiments carried out five years later with the volcanic gas, hydrogen sulphide, that he seemed to have put to one side without fully realising what he had found. Jeffrey Bada, a former student of Dr Miller's who is now a Professor of Marine Chemistry at Scripps Institution of Oceanography in San Diego, discovered the residue samples from the original 1958 experiment and analysed the contents using highly sensitive chemical techniques that were not available 50 years ago. The study, published in the journal Proceedings of the National Academy of Sciences, revealed that Dr Miller was the first scientist to synthesise important sulphur-containing amino acids in this simulation of the environment of early earth. In total, Professor Bada's team found 23 amino acids and four similar compounds known as amines in Dr Miller's discarded samples, including seven substances containing sulphur.
"This experiment marks the first synthesis of sulphur amino acids from spark-discharge experiments designed to imitate primordial environments. The relative yield of some amino acids... are the highest ever found in a spark-discharge experiment," the scientists write. Professor Bada said that Dr Miller's team was only able to use a relatively primitive technique called paper chromatography to detect the presence of organic molecules.
The creation of sulphur-containing amino acids using similar techniques was eventually confirmed in the 1970s, including in Dr Miller's lab. "Unbeknownst to him, he'd already done it in 1958," Professor Bada said.
Wednesday, March 16, 2011
Shinmoedake volcano: Japan's explosive geology explained
Volcanic lightning or a dirty thunderstorm is seen above Shinmoedake peak as it erupts on January 28. The volcano erupted again on Sunday, with the largest blast in more than half a century.
Christian Science Monitor: Shinmoedake volcano: Japan's explosive geology explained
When it comes to building a country, you'd be hard-pressed to do it in a more volatile part of the world than Japan.
About 1,500 earthquakes strike the island nation every year. Minor tremors occur on a nearly daily basis. Deadly quakes are a tragic part of the nation's past.
The anniversary of the Great Kanto Earthquake of 1923, for example, which killed more than 100,000 people around Tokyo, is now national Disaster Prevention Day. More recently, a 6.8 magnitude earthquake struck the city of Kobe in 1995, killing more than 6,000 people.
Japan has such a large potential for earthquakes — and disaster — because the nation sits atop four huge slabs of the Earth's crust, called tectonic plates. These plates mash and grind together and trigger deadly earthquakes, like the 8.9-magnitude quake that struck on Friday (March 11). [Photos: Japan Earthquake and Tsunami in Pictures]
The tectonic activity has also created explosive volcanoes, like south Japan's Mount Kirishima, which continued its recent eruptive streak today (March 14).
Japan lies along the Pacific Ring of Fire — a narrow zone around the Pacific Ocean where a large chunk of Earth's earthquakes and volcanic eruptions occur. Roughly 90 percent of all the world's earthquakes — and 80 percent of the largest ones — strike along the Ring of Fire.
Great quake
Friday's quake off the east coast of Honshu, Japan's largest island, was the fifth-largest ever recorded, according to the U.S. Geological Survey (USGS), and the largest ever recorded in Japan.
More than 150 aftershocks of magnitude 5 or greater have followed — including more than two dozen of magnitude 6 or greater. The number of aftershocks in Japan is not uncommon for an earthquake of this size, said geologist Eric Geist, of the USGS, at a news conference last week, and the rumbling could last for a year or more.
As a rule of thumb, an earthquake's largest aftershock is about one magnitude lower than the mainshock, said Paul Caruso, a geophysicist with the USGS. The largest aftershock from this earthquake has been a magnitude 7.1.
Japan's tectonic shuffle
Earthquakes typically occur along faults, which are breaks in the rocky plates of the Earth's crust. These faults accumulate strain over the years as two plates butt heads.
Japan's stretch of the Ring of Fire is where the North American, Pacific, Eurasian and Philippine plates come together. Northern Japan is largely on top of the western tip of the North American plate. Southern Japan sits mostly above the Eurasian plate.
Friday's temblor struck 231 miles (373 kilometers) northeast of Tokyo and 80 miles (130 km) east of Sendai, Honshu, in the Pacific Ocean near the Japan Trench. The Japan Trench, a subduction zone, is where the Pacific plate — beneath the Pacific Ocean — dives underneath North American plate — beneath Japan. This violent movement, called thrust faulting, forced the North American plate upward in this latest quake.
On average, the Pacific Plate is moving west at about 3.5 inches (8.9 centimeters) per year, and the movement has produced major earthquakes in the past — nine earthquakes of magnitude 7 or greater since 1973. The largest of these was a magnitude 7.8 earthquake in December 1994, which caused three fatalities and almost 700 injuries, approximately 160 miles (260 km) to the north of Friday's quake. In June of 1978, a magnitude 7.7 earthquake about 22 miles (35 km) to the southwest caused 22 fatalities and over 400 injuries.
Earthquake aftermath
The rupture during Friday's quake was almost 200 miles (322 km) long, on an underwater fault that is about 220 miles (354 km) long by about 60 miles (97 km) wide, said Tom Broker, of the USGS. Earthquakes along that fault can affect the rest of the world — literally.
"This is just a ginormous earthquake," Broker said. "It's really hard to grasp how big it is."
For one, the intense temblor accelerated Earth's spin, shortening the length of the 24-hour day by 1.8 microseconds, according to geophysicist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Japan's Earthquake Research Committee said the earthquake forced the North American plate eastward by about 66 feet (20 meters), reported Japan's national broadcast agency, NHK. The entire island of Honshu was moved about 8 feet (2.4 m) east, according to USGS scientists. Geologists in St. Louis reported that their city moved up and down a fraction of an inch during the quake, but too slowly for anyone to notice, reported the St. Louis Post-Dispatch.
Tsunami trigger
Friday's huge earthquake was about 15.2 miles (24.4 km) deep, which was shallow enough to trigger a tsunami as the seafloor was pushed up and away from Japan. As the energy from the quake rose, two waves were created. Wave heights of more than 20 feet (6 m) socked Japan's coast, where the death toll is expected to exceed 10,000, according to news reports.
At the same time, a tsunami roared across the Pacific Ocean at the ground-speed of an airplane, said Ken Hudnut of the USGS. Damage was reported in Hawaii and near the California-Oregon border.
Explosive eruptions
Colliding tectonic plates not only trigger earthquakes — they also build volcanoes. About 10 percent of the world's active volcanoes are in Japan, mostly where the Pacific Plate is diving below the Philippine Plate.
About 950 miles (1,500 km) south of Friday's earthquake, the Shinmoedake cone on the Kirishima mountain range erupted on Sunday. The blast was the volcano's largest in 52 years, the BBC reported. The volcano had been active earlier in the year, and despite the renewed activity coinciding with last week's earthquake, any link between the two would be speculation at this time, reported the Los Angeles Times.
The Pacific Ring of Fire is home to 452 volcanoes in total — that's 75 percent of the world's active and dormant volcanoes.
Monday, March 14, 2011
Mud volcano erupts in Azerbaijan
en.tren.az: Mud volcano erupts in Azerbaijan
A mud volcano erupted in the Gobustan region due to aftershocks, Geology Institute Mud Volcanoes Department Director Adil Aliyev told Trend.
He added that tremors were systematically recorded in the area.
"The institute is researching Shikhzeyirli and other mud volcanoes," Aliyev said.
The Shikhzeyirli mud volcano outside the Shikhzeyirli village in the Gobustan region erupted on March 13. A large mud-bath occurred on the surrounding area as a result of the explosion.
During the eruption, the flame height reached 60-70 meters.
JAPAN DISASTER: Underwater volcanoes pose risk to plant, activists say
Taipei Times: JAPAN DISASTER: Underwater volcanoes pose risk to plant, activists say
The earthquake that hit Japan on Friday last week has provided additional ammunition to environmental activists who are worried that one of Taiwan’s nuclear power plants lies within an area known for its underwater volcanoes.
Lee Chao-shing, a professor of applied geosciences at National Taiwan Ocean University, said last year that as many as 70 underwater volcanoes are located within an 80km radius of the soon-to-be-operational Fourth Nuclear Power Plant in Gongliao District, New Taipei City.
Up to 11 of those volcanoes are active, Lee said.
Although atomic regulatory officials dismissed the risks, activists said the authorities should take another look in light of the nuclear incidents in Japan.
The volcanoes, which have the highest concentration near a nuclear plant in the world, could lead to “a serious disaster” in the event of an earthquake or tsunami on the scale of that that struck Japan last week, Lee said.
The extent of their activity can be seen by the nearby presence of crabs, he said, pointing to video that showed hundreds of the crustaceans crawling at the base of what Lee said was an underwater volcano.
Democratic Progressive Party (DPP) legislators demanded that the government stop work on the Fourth Nuclear Power Plant — also known as the Longmen plant — which is expected to come online this year or next year.
DPP Legislator Tien Chiu-chin said the government should adopt a more cautious approach given the research findings, suggesting it was time it “stopped, looked and listened carefully.”
“The findings support ... the view that a natural disaster off Taiwan would have even more serious consequences than [what is happening] at Fukushima,” she said, referring to fears of two nuclear meltdowns at the Fukushima Dai-ichi nuclear power plant in Japan.
Kao Cheng-yan of National Taiwan University, who is actively involved in the environmental movement, said the Longmen plant should not become operational.
“The reactors in the nuclear plant would be more unstable in the event of an earthquake. There are active volcanoes all around it,” he said.
Responding to the concerns, nuclear regulatory officials said the Fourth Nuclear Power Plant is safe, pointing to its location on stable bedrock and multiple backup systems, which officials say exceed those Japan had in place.
“We believe that [construction of] the fourth nuclear plant can continue as planned,” Taiwan Power Co chairman Edward Chen said.
The earthquake that hit Japan on Friday last week has provided additional ammunition to environmental activists who are worried that one of Taiwan’s nuclear power plants lies within an area known for its underwater volcanoes.
Lee Chao-shing, a professor of applied geosciences at National Taiwan Ocean University, said last year that as many as 70 underwater volcanoes are located within an 80km radius of the soon-to-be-operational Fourth Nuclear Power Plant in Gongliao District, New Taipei City.
Up to 11 of those volcanoes are active, Lee said.
Although atomic regulatory officials dismissed the risks, activists said the authorities should take another look in light of the nuclear incidents in Japan.
The volcanoes, which have the highest concentration near a nuclear plant in the world, could lead to “a serious disaster” in the event of an earthquake or tsunami on the scale of that that struck Japan last week, Lee said.
The extent of their activity can be seen by the nearby presence of crabs, he said, pointing to video that showed hundreds of the crustaceans crawling at the base of what Lee said was an underwater volcano.
Democratic Progressive Party (DPP) legislators demanded that the government stop work on the Fourth Nuclear Power Plant — also known as the Longmen plant — which is expected to come online this year or next year.
DPP Legislator Tien Chiu-chin said the government should adopt a more cautious approach given the research findings, suggesting it was time it “stopped, looked and listened carefully.”
“The findings support ... the view that a natural disaster off Taiwan would have even more serious consequences than [what is happening] at Fukushima,” she said, referring to fears of two nuclear meltdowns at the Fukushima Dai-ichi nuclear power plant in Japan.
Kao Cheng-yan of National Taiwan University, who is actively involved in the environmental movement, said the Longmen plant should not become operational.
“The reactors in the nuclear plant would be more unstable in the event of an earthquake. There are active volcanoes all around it,” he said.
Responding to the concerns, nuclear regulatory officials said the Fourth Nuclear Power Plant is safe, pointing to its location on stable bedrock and multiple backup systems, which officials say exceed those Japan had in place.
“We believe that [construction of] the fourth nuclear plant can continue as planned,” Taiwan Power Co chairman Edward Chen said.
As if an earthquake, tsunami and potential nuclear meltdown weren't enough... now disaster-ravaged Japan suffers a volcanic eruption
Daily Mail Online: As if an earthquake, tsunami and potential nuclear meltdown weren't enough... now disaster-ravaged Japan suffers a volcanic eruption
volcano has erupted in Japan, compounding the problems in the disaster-ravaged country.
Following Friday's megaquake and resulting tsunami which took the lives of thousands along the east coast, the Shinmoedake volcano in south-western Japan erupted yesterday, sending ash and rock over two miles into the air.
The explosion shattered windows as far as four miles away, adding to the terror the country has suffered over the past few days.
An area of over a mile around the volcano, located in the Kirishima range on the southern Kyushu island, was evacuated and hundreds fled as roasting hot ash rained down from the mountain.
A volcano warning at level three out of five is currently in place, but that could be increased since it is believed a dome if lava is now forming in the crater.
volcano has erupted in Japan, compounding the problems in the disaster-ravaged country.
Following Friday's megaquake and resulting tsunami which took the lives of thousands along the east coast, the Shinmoedake volcano in south-western Japan erupted yesterday, sending ash and rock over two miles into the air.
The explosion shattered windows as far as four miles away, adding to the terror the country has suffered over the past few days.
An area of over a mile around the volcano, located in the Kirishima range on the southern Kyushu island, was evacuated and hundreds fled as roasting hot ash rained down from the mountain.
A volcano warning at level three out of five is currently in place, but that could be increased since it is believed a dome if lava is now forming in the crater.
Thursday, March 10, 2011
Hawaii's Kilauea volcano erupts with greater fury
Reuters: Hawaii's Kilauea volcano erupts with greater fury
HONOLULU (Reuters) - The frequently restive Kilauea volcano on the island of Hawaii spewed a plume of lava 160 feet tall on Wednesday, more than twice as high as molten rock shot into the sky when eruptions flared anew on Saturday.
As eruptions continued at two spots, seismic activity grew more vigorous and poisonous sulfur dioxide gas emissions peaked at 10,000 tons per day, over 30 times last weekend's levels, before dropping off again by more than half, according to scientists at the U.S. Geological Survey.
The 2,000-degree Fahrenheit molten lava from Kilauea's summit and the newly ruptured Kamoamoa fissure have destroyed 78 acres of rain forest since Saturday and buried 162 acres of park land.
The ground around the eruptions has continued to collapse, and forests downwind of the fissure were choked with volcanic fumes that are toxic to the vegetation, said Mardie Lane, an official at the Hawaii Volcano Observatory.
"We've been fortunate that we've had showers and rain," Lane told Reuters. "One of the biggest unknown dangers is the spread of sulfur dioxide gas. It's invisible, noxious and toxic. When our rangers are in the field, they use respirators to filter out the harmful gases."
No injuries to people or damage to residential property has been reported since Kilauea roared back to life on Saturday. USGS scientists continued to monitor the activity.
Kilauea is one of five volcanoes that formed the Big Island, officially known as the island of Hawaii. Periodic eruptions of the volcano have destroyed 213 homes since the volcano emerged from a period of dormancy in 1983.
The latest episode began with the 370-foot collapse of the floor of the Pu'u O'o crater and opening of the 535-yard long Kamoamoa fissure on March 5.
HONOLULU (Reuters) - The frequently restive Kilauea volcano on the island of Hawaii spewed a plume of lava 160 feet tall on Wednesday, more than twice as high as molten rock shot into the sky when eruptions flared anew on Saturday.
As eruptions continued at two spots, seismic activity grew more vigorous and poisonous sulfur dioxide gas emissions peaked at 10,000 tons per day, over 30 times last weekend's levels, before dropping off again by more than half, according to scientists at the U.S. Geological Survey.
The 2,000-degree Fahrenheit molten lava from Kilauea's summit and the newly ruptured Kamoamoa fissure have destroyed 78 acres of rain forest since Saturday and buried 162 acres of park land.
The ground around the eruptions has continued to collapse, and forests downwind of the fissure were choked with volcanic fumes that are toxic to the vegetation, said Mardie Lane, an official at the Hawaii Volcano Observatory.
"We've been fortunate that we've had showers and rain," Lane told Reuters. "One of the biggest unknown dangers is the spread of sulfur dioxide gas. It's invisible, noxious and toxic. When our rangers are in the field, they use respirators to filter out the harmful gases."
No injuries to people or damage to residential property has been reported since Kilauea roared back to life on Saturday. USGS scientists continued to monitor the activity.
Kilauea is one of five volcanoes that formed the Big Island, officially known as the island of Hawaii. Periodic eruptions of the volcano have destroyed 213 homes since the volcano emerged from a period of dormancy in 1983.
The latest episode began with the 370-foot collapse of the floor of the Pu'u O'o crater and opening of the 535-yard long Kamoamoa fissure on March 5.
Wednesday, March 9, 2011
Reunited after 2,000 years apart: The Pompeii husband and wife whose tomb was buried by Vesuvius
Daily Mail Online: Reunited after 2,000 years apart: The Pompeii husband and wife whose tomb was buried by Vesuvius
Nearly 2,000 years after the eruption of Mount Vesuvius broke apart a tomb inscription for a husband and wife, the couple's names have been reunited with the recovery of a missing marble fragment.
Pompeii, which had existed for 700 years, was snuffed out in just 24 hours when Vesuvius erupted on the morning of August 24, 79 A.D.
The volcano began spewing ash, mud and noxious gases without warning and a 12-mile high black cloud from the volcano blocked out the sun.
Now marble fragments from a tomb smashed apart and buried during the eruption have finally been joined together, uniting the names of the couple 2,000 years later.
Still under construction at the time of the eruption, the tomb in which the married couple were buried, known as the 'Tomb of the Marble Door' had been used for a number of burials.
It is believed the inscription was displayed temporarily to be later embedded in the face of the tomb once the structure was completed, but this never happened as the volcano buried the entire city.
Archaeologists found the tomb fragments 16 centuries later and they were stored in the deposits of the National Archaeological Museum of Naples.
According to the original excavation report, the fragmentary inscription consisted of seven pieces of marble.
The missing piece, containing the name of a female, 'Servilia', was in the same museum, but until now had not been recognized as part of the same inscription.
Although there are some other small pieces missing, the inscription put together by archaeologists is now legible and reads:
'Lucius Catilius Pamphilus, freedman of Lucius, member of the Collinian tribe, for his wife Servilia, in a loving spirit.'
An outsider to the Pompeian establishment, historians believe Caltilius Pamphilus was a former slave who took great pride in his status.
The Caltilii family became fairly powerful at a slightly later phase of Pompeii, under the rule of Nero, they say.
Giuseppe Camodeca, professor of Roman history and Latin epigraphy at the University of Naples 'L'Orientale,' says he firmly believes that the piece with Servilia's name is the one that completes the marble jigsaw of fragments.
It was Mr Camodeca who several years ago reassembled the first six fragments at the museum in Naples.
While four pieces referred to Lucius Caltilius Pamphilus, two fragments contained the Latin word 'uxori,' indicating a wife.
Historians identified the missing wife by examining photographs of fragments of inscriptions stored at the Naples museum.
An exhibition in New York, Pompeii The Exhibit: Life and Death in the Shadow of Vesuvius is due to open on Friday.
It chronicles life in the vibrant mercantile city before and after Vesuvius erupted, and includes many body casts made of the inhabitants, including a crouching man covering his mouth, a chained dog and a family of four huddling together.
Nearly 2,000 years after the eruption of Mount Vesuvius broke apart a tomb inscription for a husband and wife, the couple's names have been reunited with the recovery of a missing marble fragment.
Pompeii, which had existed for 700 years, was snuffed out in just 24 hours when Vesuvius erupted on the morning of August 24, 79 A.D.
The volcano began spewing ash, mud and noxious gases without warning and a 12-mile high black cloud from the volcano blocked out the sun.
Now marble fragments from a tomb smashed apart and buried during the eruption have finally been joined together, uniting the names of the couple 2,000 years later.
Still under construction at the time of the eruption, the tomb in which the married couple were buried, known as the 'Tomb of the Marble Door' had been used for a number of burials.
It is believed the inscription was displayed temporarily to be later embedded in the face of the tomb once the structure was completed, but this never happened as the volcano buried the entire city.
Archaeologists found the tomb fragments 16 centuries later and they were stored in the deposits of the National Archaeological Museum of Naples.
According to the original excavation report, the fragmentary inscription consisted of seven pieces of marble.
The missing piece, containing the name of a female, 'Servilia', was in the same museum, but until now had not been recognized as part of the same inscription.
Although there are some other small pieces missing, the inscription put together by archaeologists is now legible and reads:
'Lucius Catilius Pamphilus, freedman of Lucius, member of the Collinian tribe, for his wife Servilia, in a loving spirit.'
An outsider to the Pompeian establishment, historians believe Caltilius Pamphilus was a former slave who took great pride in his status.
The Caltilii family became fairly powerful at a slightly later phase of Pompeii, under the rule of Nero, they say.
Giuseppe Camodeca, professor of Roman history and Latin epigraphy at the University of Naples 'L'Orientale,' says he firmly believes that the piece with Servilia's name is the one that completes the marble jigsaw of fragments.
It was Mr Camodeca who several years ago reassembled the first six fragments at the museum in Naples.
While four pieces referred to Lucius Caltilius Pamphilus, two fragments contained the Latin word 'uxori,' indicating a wife.
Historians identified the missing wife by examining photographs of fragments of inscriptions stored at the Naples museum.
An exhibition in New York, Pompeii The Exhibit: Life and Death in the Shadow of Vesuvius is due to open on Friday.
It chronicles life in the vibrant mercantile city before and after Vesuvius erupted, and includes many body casts made of the inhabitants, including a crouching man covering his mouth, a chained dog and a family of four huddling together.
Newcomer or Old-timer – Current Eruption Captivates
Big Island VideoNews.com: Newcomer or Old-timer – Current Eruption Captivates
The Kamoamoa Fissure Eruption that began March 5, 2011, continues on the east rift of Kilauea Volcano.
Lava spatters sporadically to heights of 100′ from a series of fissues that extend more than a mile between Napau Crater and Pu`u `O`o. Around the vents, the ground trembles and molten rock pools and flows.
In response to the change in volcanic conditions, nearly thirty park personnel have rallied to support this major incident, meeting and planning for the first time in the park’s new Visitor Emergency Operations Center.
Rangers remain vigilant. Seismicity is ongoing, the volcano’s summit continues to deflate, and magma migrates underground beneath roads, trails, and campsites. Most of the park remains open, however temporary closures help ensure that hikers, bikers, and cars don’t get trapped on the ‘wrong side’ of an outbreak.
USGS Hawaiian Volcano Observatory scientists seize this opportunity to collect lava samples, map a changing landscape, and measure surface deformation. Instruments record sulfur dioxide gas emissions at a breath-taking 10,000 tons a day.
Park firefighters gauge the threat of lava-ignited wildfires. Nearly 200 acres have been burned and buried. Fortunately for now, passing showers offer a reprieve from potential flare-ups in native rain forest.
Public and media interest is keen and visitation is up. Because the eruption is remote and inaccessible, rangers post the latest information, photos, and videos at Kilauea Visitor Center and Jaggar Museum. A webcam view is available on-line at http://volcanoes.usgs.gov/hvo/cams/NCcam/
It’s a phenomenal time, and for some, deja vu. The volcanic event is happening where it all began twenty-eight years ago. On January 3, 1983, Kilauea’s ongoing east rift eruption opened in this very location. Anxious newcomers can’t help but wonder “What happens next?” Old-timers take pause and ponder, and share an occasional “I remember when… “
Volcano Glossary Part 7
tsunami - large waves formed by large undersea landslides commonly caused by earthquakes. From the Japanese word for seismic sea wave. (misnamed tidal wave, though it has nothing to do with tides.)
tuff - volcanic ash hardened by pressure or from natural cements deposited from water that seeps through the ground.
volcanic - pertaining to a volcano
volcaniclastic - refers to the clastic rocks composed of volcanic particles.
volcanic ash - fragmental pieces of glass, vcrystals, and rock fragments, less than 0.4 inchin diameter, extruded by volcanoes.
volcanic sandstone - a rock composed mostly of sand0sized volcanic particles.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
tuff - volcanic ash hardened by pressure or from natural cements deposited from water that seeps through the ground.
volcanic - pertaining to a volcano
volcaniclastic - refers to the clastic rocks composed of volcanic particles.
volcanic ash - fragmental pieces of glass, vcrystals, and rock fragments, less than 0.4 inchin diameter, extruded by volcanoes.
volcanic sandstone - a rock composed mostly of sand0sized volcanic particles.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
Monday, March 7, 2011
Worlds Most Active Volcanoes
Stromboli
Kilauea
Yasur
Etna
Christian Science Monitor: World's Most Active Volcnaoes
Mount Merapi, located near Yogyakarta, Indonesia, is one of the country's most volatile volcanoes. It began erupting at dusk on Tuesday [March 1, 2011), and thousands evacuated the area surrounding it. It didn't come as a shock, as scientists have been expecting an eruption for a while.
Here are some of the world's most active volcanoes.
4. Stromboli (Italy)
Stromboli is the name of both a small island northwest of Sicily and the volcano that made it. The volcano has been erupting regularly, but mildly, for about 2,000 years and its nighttime explosions have made it a major tourist attraction. While minor eruptions occur about every 10 to 20 minutes, Stromboli also has had some more serious eruptions that have prompted evacuations or deaths, mainly from debris. However, because eruptions mostly happen near the summit, about 700 people are able to make a home on the island. Its last major eruption happened in July 2010.
3. Mount Yasur (Vanuatu)
Located in the southwest Pacific on Tanna Island in Vanuatu, Mount Yasur is part of the Pacific Ring of Fire, a string of volcanoes. It erupts almost constantly, with most measurements indicating an eruption several times an hour for several centuries. Because of the almost constant volcanic activity it is a popular tourist destination. Sometimes tourists are able to climb all the way to the summit. Mt. Yasur has been nicknamed "The Lighthouse of the Pacific" because it is constantly alight from eruptions.
2. Kilauea (Hawaii)
Kilauea, located on Hawaii's Big Island, has erupted uninterruptedly since 1983 and nearly constantly for as long as records have been kept. It is Hawaii's most active volcano and 70 percent of its surface is less than 600 years old. The eruption that began in 1983 has steadily added coastline to the island.
1. Mount Etna (Italy)
Mount Etna, located in Sicily, Italy, is Europe's largest volcano and one of its most active. Records of vulcanism date to 1500 BC. It erupts in several different ways and places, making it unpredictable for those living in the area. It is almost 11,000 feet tall, though it's precised altitude is in constant flux because of eruptions and other disturbances, and much of its surface is lava from previous eruptions.
7 Mar, 2011: Why did Hawaii's Kilauea volcano shoot lava 80 feet into the air?
Christian Science Monitor: Why did Hawaii's Kilauea volcano shoot lava 80 feet into the air?
A cinder cone brimming with a lava lake, on the flank of Hawaii's Kilauea volcano, appeared to drain suddenly over the weekend, its molten rock apparently finding outlet in a new fissure that opened farther down slope.
The cone, named Pu'u 'O'o, saw its "floor" plunge 370 feet as the lava beneath found a weak area in Kilauea's flank. The floor actually a thin crust of cooler material that sits atop the molten rock like skin on pudding.
In addition, lava-lake levels in Halema'uma'u Crater, which sits inside the large caldera at the top of Kilauea, dropped significantly as well, according to scientists at the US Geological Survey's Hawaii Volcano Observatory. The observatory is perched near the caldera's edge.
With Pu'u 'O'o as an outlet, Kilauea has been erupting non-stop since 1983, giving scientists and tourists alike a window on how Earth replenishes the thin skin of rock that makes up the planet's crust.
The opening of the crack on Saturday "is quite an exciting development," says James Deiterich, a geophysicist at the University of California at Riverside who studies Hawaii's volcanoes. "For several years the eruption has been very boring. There's been no change in its pattern at all" – just lava slowly rising and falling as Pu'u 'O'o went through its paces.
Dr. Deiterich explains that while he hasn't seen much of the data yet from the weekend breakout, the event appears to be common to volcanoes of Kilauea's type – a so-called shield volcano.
Shield volcanoes tend to ooze relatively thin, gas-poor lava over the tops of their craters or through fissures that open along their flanks as magma pushes up, causing the slopes to develop cracks. Regions where the cracks appear are known as rift zones. Pu'u 'O'o is the most active outlet in Kilauea's eastern rift zone.
The slope where the fissure appeared has been building a bulge for some time, Deiterich says.
Given a choice, lava would rather take the path of least resistance – like a weak spot lower on the slope – than continue to push its mass vertically to overtop the cinder cone's throat.
Although shield-volcano eruptions can generate spectacular fountains of lava – in the case of this weekend's plumbing change, up to 80 feet high – the eruptions tend to be tame compared with the violent blasts from steeper-sloped stratovolcanoes, such as those found in Indonesia, Chile, or the Pacific Northwest, for instance.
Magmas in these volcanoes tend to be a thicker mix of material and richer in gases, leading to explosive eruptions.
Although lava can overtop a stratovolcano's summit as well, the thicker molten goo doesn't travel as far from the cone as does the thinner lavas from shield volcanoes – a trait that gives the shield volcanoes their wide, low-slung look.
But the look can be deceiving. Kilauea's large sibling, Mauna Loa, rises to just over 13,700 feet above sea level. The mountain's roots lie some 16,400 feet below sea level, making it, as well as its slightly taller sister, Mauna Kea, taller than Mt. Everest.
For its part, Kilauea marks the most active part of a hot spot in Earth's crust that is thought to have formed the Hawaiian island chain during the past 28 million years. Researchers say the hot spot consists of a long-lasting plume of magma beneath a weak patch of undersea crust. Magma breaching the crust formed undersea volcanoes, which slowly grew until they could poke above sea level. Hawai'i's volcanoes sit far from the boundaries of crustal plates, where the bulk of Earth's volcanic activity takes place.
Scientists still argue over whether the chain was created as the Pacific Plate moved over the hot spot to give the chain its follow-the-leader pattern or whether the hot spot itself does some of the moving.
A cinder cone brimming with a lava lake, on the flank of Hawaii's Kilauea volcano, appeared to drain suddenly over the weekend, its molten rock apparently finding outlet in a new fissure that opened farther down slope.
The cone, named Pu'u 'O'o, saw its "floor" plunge 370 feet as the lava beneath found a weak area in Kilauea's flank. The floor actually a thin crust of cooler material that sits atop the molten rock like skin on pudding.
In addition, lava-lake levels in Halema'uma'u Crater, which sits inside the large caldera at the top of Kilauea, dropped significantly as well, according to scientists at the US Geological Survey's Hawaii Volcano Observatory. The observatory is perched near the caldera's edge.
With Pu'u 'O'o as an outlet, Kilauea has been erupting non-stop since 1983, giving scientists and tourists alike a window on how Earth replenishes the thin skin of rock that makes up the planet's crust.
The opening of the crack on Saturday "is quite an exciting development," says James Deiterich, a geophysicist at the University of California at Riverside who studies Hawaii's volcanoes. "For several years the eruption has been very boring. There's been no change in its pattern at all" – just lava slowly rising and falling as Pu'u 'O'o went through its paces.
Dr. Deiterich explains that while he hasn't seen much of the data yet from the weekend breakout, the event appears to be common to volcanoes of Kilauea's type – a so-called shield volcano.
Shield volcanoes tend to ooze relatively thin, gas-poor lava over the tops of their craters or through fissures that open along their flanks as magma pushes up, causing the slopes to develop cracks. Regions where the cracks appear are known as rift zones. Pu'u 'O'o is the most active outlet in Kilauea's eastern rift zone.
The slope where the fissure appeared has been building a bulge for some time, Deiterich says.
Given a choice, lava would rather take the path of least resistance – like a weak spot lower on the slope – than continue to push its mass vertically to overtop the cinder cone's throat.
Although shield-volcano eruptions can generate spectacular fountains of lava – in the case of this weekend's plumbing change, up to 80 feet high – the eruptions tend to be tame compared with the violent blasts from steeper-sloped stratovolcanoes, such as those found in Indonesia, Chile, or the Pacific Northwest, for instance.
Magmas in these volcanoes tend to be a thicker mix of material and richer in gases, leading to explosive eruptions.
Although lava can overtop a stratovolcano's summit as well, the thicker molten goo doesn't travel as far from the cone as does the thinner lavas from shield volcanoes – a trait that gives the shield volcanoes their wide, low-slung look.
But the look can be deceiving. Kilauea's large sibling, Mauna Loa, rises to just over 13,700 feet above sea level. The mountain's roots lie some 16,400 feet below sea level, making it, as well as its slightly taller sister, Mauna Kea, taller than Mt. Everest.
For its part, Kilauea marks the most active part of a hot spot in Earth's crust that is thought to have formed the Hawaiian island chain during the past 28 million years. Researchers say the hot spot consists of a long-lasting plume of magma beneath a weak patch of undersea crust. Magma breaching the crust formed undersea volcanoes, which slowly grew until they could poke above sea level. Hawai'i's volcanoes sit far from the boundaries of crustal plates, where the bulk of Earth's volcanic activity takes place.
Scientists still argue over whether the chain was created as the Pacific Plate moved over the hot spot to give the chain its follow-the-leader pattern or whether the hot spot itself does some of the moving.
Volcano Glossary Part 6
sandstone - a sedimentary rock formed of cemented grains with diameters less than .04 inches.
sedimentary - refers to various aspects of sediments, which are layered deposits of rock and mineral particles.
scoria - a rough-surfaced pyroclastic fragment, baseball to nut size, formed directly from magma and explosively ejected to the surface. It is gaseous and therefore has many bubbles (vesicles) form within the viscous material; synonymus with cinder.
seismograph - a machine that records the intensity of earthquakes.
spatter cone - a small cone made of hot, gas-rich bombs of fluid basalt lava that fall and stick together around a vent.
strata - layers of rock are said to be stratified and are referred to in the plural as stra; an individual layer is a stratum.
Strombolian eruption - an eruption that produces high-arcing incandescent "rooster tails", reminiscent of colorful, fireworks fountains. The ejecta are mainly basaltic cinders and bombs that construct cinder cones. (Named after the Stromboli volcano on the island of Stromboli, off the north coast of Sicily, which erupts in this way.)
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
sedimentary - refers to various aspects of sediments, which are layered deposits of rock and mineral particles.
scoria - a rough-surfaced pyroclastic fragment, baseball to nut size, formed directly from magma and explosively ejected to the surface. It is gaseous and therefore has many bubbles (vesicles) form within the viscous material; synonymus with cinder.
seismograph - a machine that records the intensity of earthquakes.
spatter cone - a small cone made of hot, gas-rich bombs of fluid basalt lava that fall and stick together around a vent.
strata - layers of rock are said to be stratified and are referred to in the plural as stra; an individual layer is a stratum.
Strombolian eruption - an eruption that produces high-arcing incandescent "rooster tails", reminiscent of colorful, fireworks fountains. The ejecta are mainly basaltic cinders and bombs that construct cinder cones. (Named after the Stromboli volcano on the island of Stromboli, off the north coast of Sicily, which erupts in this way.)
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
Saturday, March 5, 2011
Volcano Glossary Part 4
Maar - a small volcano with wide diameter relative to its height, often with a bowl-shaped crater.
magma - molten rock with contained gases that forms within or somewhat below the earth's crust. It is ejected in highly explosive eruptions to form pyroclasts or lava flows.
magmatic eruption - an explosive eruption from the sudden expansion of magma from internal gas pressure.
nuèe ardente - a hot, heavier-than-air, turbulent "volcanic hurricane" composed of a mixture of hot gases and solid particles. Nuèes ardentes flow rapidly down the slopes of a volcano, ofren attaining speeds fifty to one hundred miles an hour.Such flows commonly form in two parts, a lower "glowing avalance" and an upper "glowing cloud."
pahoehoe lava - lava that has a smooth surface after cooling, compared with the roughness of aa.
Pelèan eruption - an eruption that produces a nuèe ardente, such as that at Mount Pele in 1902.
Plinian eruption - an eruption that forms ash clouds above the volcano to heights as much as thirty miles into the atmosphere. (Named after the eruption of Mount Vesuvius in 72 AD that killed Pliny the elder.)
pumice - a glass foam formed by frothing gas-rich magma. Pumice is very light weight and can float in water.
pyroclastic - refers to the fragmental materials formed by explosive processes of volcanoes.
pyroclastic flow: a heavier-than-air, hurricane-like, non-turbulent cloud of volcanic particles mixed with hot gases, more dense than a pyroclastic flow.
pyroclastic surge - a heavier-than-air, hurricane-like, turbulent cloud of volcanic particles mixed with hot gases, less dense than a pyroclastic flow.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
magma - molten rock with contained gases that forms within or somewhat below the earth's crust. It is ejected in highly explosive eruptions to form pyroclasts or lava flows.
magmatic eruption - an explosive eruption from the sudden expansion of magma from internal gas pressure.
nuèe ardente - a hot, heavier-than-air, turbulent "volcanic hurricane" composed of a mixture of hot gases and solid particles. Nuèes ardentes flow rapidly down the slopes of a volcano, ofren attaining speeds fifty to one hundred miles an hour.Such flows commonly form in two parts, a lower "glowing avalance" and an upper "glowing cloud."
pahoehoe lava - lava that has a smooth surface after cooling, compared with the roughness of aa.
Pelèan eruption - an eruption that produces a nuèe ardente, such as that at Mount Pele in 1902.
Plinian eruption - an eruption that forms ash clouds above the volcano to heights as much as thirty miles into the atmosphere. (Named after the eruption of Mount Vesuvius in 72 AD that killed Pliny the elder.)
pumice - a glass foam formed by frothing gas-rich magma. Pumice is very light weight and can float in water.
pyroclastic - refers to the fragmental materials formed by explosive processes of volcanoes.
pyroclastic flow: a heavier-than-air, hurricane-like, non-turbulent cloud of volcanic particles mixed with hot gases, more dense than a pyroclastic flow.
pyroclastic surge - a heavier-than-air, hurricane-like, turbulent cloud of volcanic particles mixed with hot gases, less dense than a pyroclastic flow.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
Thursday, March 3, 2011
Volcano Glossary Part 3
ignimbrite - a deposit of a pyroclastic flow or pyroclastic surge or both.
lapilli - pyroclastic particles ranging in size from .04 to 2.6 inches.
laterite - soil so rich in iron oxide that it may be mined as an iron ore.
lava - a volcanic effusion of molten rock that flows upon the ground, also solidified lava.
limestone - a rock composed of an aggregate of calcium carbonate minerals.
littoral cone - a mound of volcanic particles formed when hot lava mixes with water at the shoreline of a body of water and explodes. The mound is a cone that looks like a volcano but has no underground vent.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
lapilli - pyroclastic particles ranging in size from .04 to 2.6 inches.
laterite - soil so rich in iron oxide that it may be mined as an iron ore.
lava - a volcanic effusion of molten rock that flows upon the ground, also solidified lava.
limestone - a rock composed of an aggregate of calcium carbonate minerals.
littoral cone - a mound of volcanic particles formed when hot lava mixes with water at the shoreline of a body of water and explodes. The mound is a cone that looks like a volcano but has no underground vent.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
Tuesday, March 1, 2011
Volcano Glossary Part 2
caldera - a crater larger than five miles in diameter formed by collapse of the ground or volcano into an underground cavity formed by the ejection of an equivalent amount of pyroclastic material. Some calderas are more than 40 miles in diameter.
cinder - a rough-surfaced pyroclastic fragment baseball to nut size, formed directly from magma and explosively ejected to the surface. It is gaseous and therefore many bubbles (vesicles) form within the viscous material. Synonymous with scoria.
cinder cone - a volcano formed by cinders that pile up around an active vent.
cross beds - a bed of layered laminations (very thin layers) truncated by other layers across eroded edges within a larger layer, or within an assemblage of layers.
dome - a dome-shaped protrustion of solidified magma formed by slow extrusion of highly viscous magma located on the side of, or within, the crater of a volcano.
ejecta - Pyroclastic material explosively ejected from a volcano.
fallout - Acumumlation of pyroclastic material that falls from the sky.
fumarole - a vent from which gases form magma - or steam created by hot magma-heating water-escape into the atmosphere.
hydrovolcanic eruption - an explosion or eruption caused by sudden expansion of water when mixed with magma.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
cinder - a rough-surfaced pyroclastic fragment baseball to nut size, formed directly from magma and explosively ejected to the surface. It is gaseous and therefore many bubbles (vesicles) form within the viscous material. Synonymous with scoria.
cinder cone - a volcano formed by cinders that pile up around an active vent.
cross beds - a bed of layered laminations (very thin layers) truncated by other layers across eroded edges within a larger layer, or within an assemblage of layers.
dome - a dome-shaped protrustion of solidified magma formed by slow extrusion of highly viscous magma located on the side of, or within, the crater of a volcano.
ejecta - Pyroclastic material explosively ejected from a volcano.
fallout - Acumumlation of pyroclastic material that falls from the sky.
fumarole - a vent from which gases form magma - or steam created by hot magma-heating water-escape into the atmosphere.
hydrovolcanic eruption - an explosion or eruption caused by sudden expansion of water when mixed with magma.
Bibliography
Out of the Crater: Chronicles of a Volcanologist, Richard V. Fisher, Princeton University Press, 1999
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