Thursday, March 30, 2006
Volcanic eruption made history
Research by Greek volcanologist George Vougioukalakis, highlighted in the new IMAX movie "Greece: Secrets of the Past," has shed light on the pyrotechnic blast that buried the island in the spring of 1646 B.C. But questions about what happened to the Minoan people of Santorini remain buried in ancient volcanic soils. - - - Q: Places as improbable as Antarctica have been linked to the Atlantis myth. Why does Santorini seem a likely candidate? A: I cannot accept any of these ties if it must be scientifically strict with what Plato says.
But the most probable scenario is that Plato created the myth based on what was known at that time of the destruction of the civilization at Santorini. We have topography, the colors that are very similar to the myth. The second point is that everything regarding the high state the civilization achieved fits with what happened to the Minoan civilization - how it was organized, the society, the level of architecture, the way they worked with nature, a high level of technical possibilities.
These things lead us to consider that Plato used the example of the Santorini eruption to create a myth to convince Athenians to be very careful with democracy, not to attack each other. Q: What methods did you use to date the volcano's eruption? A: We have used radiocarbon dating from charcoal found in the soil that was covered by the Minoan eruption. And we have tree ring dating from Turkey to California that registers the heavy volcanic eruption.
And we have ice cores in Greenland that show the high sulfuric rain and fine ash that could be contributed to the Santorini eruption. All these bring us to the same date: 1646 B.C., plus or minus 20 years. Q: How did the date - a century earlier than once thought - change scientists' ideas about the Minoan culture? A: There are still a lot of open questions. What is clear regarding this age is that the Minoan culture continued to exist after the eruption, based on dating of pottery.
We have to find other causes for the Minoan decline (besides the volcano). In my opinion, it is most probable there was a social effect. They didn't have the power to continue.
Q: You've shown that no one could have survived the eruption or the tsunamis it generated at sea. What do scientists make of the fact that no bodies have been uncovered at Santorini?
A: I think it's the same as in Pompeii. We expect to find the people in the harbor waiting to leave or in some open areas where they were grouped trying to escape. I think you must have in mind that we have excavated only 5 percent of the occupied area. I think when we begin to excavate near the port, the people will be there. We know that there had been an earthquake a short time before, and the people had returned, started to clear the debris and rebuild. When the eruption began, they would not have had time to move out of the settlement, not more than a few hundred meters.
Q: How long might it take to find bodies?
A: Excavation began in 1976, and it has to go on for tens of years or even 100 years. It is extremely difficult to excavate a single layer and try to conserve what is below. Now modern ideas about excavation are very different from old ideas. We have to imagine it will take a long, long time.
Q: You've estimated that Santorini erupted with the force of 40 atomic bombs - 100 times more powerful than Vesuvius in A.D. 79. Could this happen today?
A: What we accept is that this probably won't happen in the next few years. There have been smaller eruptions in 1925, 1940 and 1950. What we want are these smaller eruptions so that people can stay there and have a nice view of the eruptions. Now we have a very good monitoring system and will be able to forecast a good period before it happens, so no one is in danger.
Q: Does the IMAX film convey the reality of your work?
A: It is amazing in that it is scientifically correct and simple. This is a very strong point because it's very difficult to tell simple and correct stories. From my point of view, this is a very important thing.
Tuesday, March 28, 2006
Six minor eruptions closed park
The national Vulcanological and Seismological Observatory said some impact craters were found 700m away. No lava was expelled.Authorities said they noticed a spike of activity within the volcano on March 17.Hundreds of thousands of visitors from across Costa Rica and around the world visit Poas and the surrounding park each year. Located about 60km north of the capital of San Jose, the reserve is also popular for its lagoons which formed as rainwater-filled craters.
Volcanic activity last shut down the park in 1994, but Poas has erupted repeatedly since 1828, often with volcanic heat causing geyser-like explosions of water.In 1990, acidic gases from the volcano damaged 20 000 acres of nearby crops.
Sunday, March 26, 2006
Drilling in hot volcano hoping to find source of geothermal power
Twenty years ago, geologist Gudmundur Omar Friedleifsson had a surprise when he lowered a thermometer down a borehole.
"We melted the thermometer," he recalls. "It was set for 380C; but it just melted. The temperature could have been 400 or even 500."
Speaking in the first of a new series on BBC Radio 4, called Five Holes in the Ground, he describes how this set him thinking about how much energy it might be possible to extract from Iceland's volcanic rocks.
At depth, the groundwater is way over 100C, but the pressure keeps it liquid. As Dr Friedleifsson puts it: "On the surface, you boil your egg at 100 degrees; but if you wanted to boil your egg at a depth of 2,500m, it would take 350."
The landscape on the Reykjanes Ridge in southwest Iceland seems like an alien world.
There are pools of boiling mud and the hiss of steam escaping from fissures. There are also signs of industry - past, present and future - with an abandoned salt factory, working geothermal power stations and a big new drilling rig.
It is also an area of great natural beauty. Down on the shore, crashing Atlantic breakers are exposing fresh cliffs of pillow basalt, volcanic lava that has erupted under the sea and been rapidly quenched so that it forms features that look a bit like black toothpaste squeezed from a giant tube.
This is a young landscape. The most recent eruptions here occurred in the 13th Century and there could be new ones at any time.
Iceland is unusual geologically in that it exists above the ocean at all. It stands on the mid-ocean ridge system, the longest mountain range on the planet. This range runs around the world's oceans like the seam on a tennis ball.
It is here that new ocean floor is created as the continents drift apart.
For the most part, it is deep under the sea; it is the place where hydrothermal vents and their "black smokers" belch out super-heated water and dissolved minerals.
But Iceland stands on an additional plume of volcanic mantle rock that has lifted it above the Atlantic and made it accessible to geologists.
Iceland is already littered with geothermal power stations, producing most of the country's electricity from steam at around 240C, extracted from boreholes between 600 and 1,000m deep.
But now, the plan is to go much deeper. Omar Friedleifsson of the Iceland Geosurvey is leading the consortium of energy companies in the Iceland Deep Drilling Project.
Iceland could become the Kuwait of the North
Albert Albertsson, power station managerLast year, they drilled down to a depth of 3,082m and since then have been conducting flow tests.
Later this year, they will put a pressure lining into their borehole and drill on down to more than 4km deep.
At that depth, they hope to encounter what is called supercritical water: water that is not simply a mixture of steam and hot water but a single phase which can carry much more energy.
Engineers on the project have calculated that increasing the temperature by 200 degrees and the pressure by 200 Bar will mean that, for the same flow rate, the energy extracted from such a borehole will go up from 5MW to 50MW.
Power station manager Albert Albertsson predicts that, by the end of the century, "Iceland could become the Kuwait of the North", exporting energy in the form of liquid hydrogen as part of a new hydrogen economy.
Interest in the Iceland Deep Drilling Project is not solely for energy production.
Geologists have never had the chance before to penetrate the volcanic heart of a mid-ocean-ridge geothermal system and there is much they would like to learn.
As they get deeper, bore teams will change from the rotary drill, which produces rock fragments but can drill up to 200m per day, to a slower drill that produces useful core samples.
The project wants to study the geology, the energy flow and the chemical environment at great depth.
Blue Lagoon: A perfect place for a dip, especially during winterAlbert Albertson, at the nearby power station, likes to think of the energy as just a part of an integrated system.
Iceland's volcanic rocks are highly fractured and so, below about 50m, there is plenty of water.
For the next 40m or thereabouts, it is fresh drinking water, topped up by Iceland's generous rainfall. Below that, the water is salty; the ocean has managed to seep in.
However, it is the really deep supercritical water that is also laden with dissolved minerals. Mr Albertsson believes he may also be able to extract precious metals, such as copper, silver and gold from the water.
After the water has gone through his turbines, it is still at about 40C. Some of that excess energy is used for district heating and for horticulture in greenhouses.
It also warms one of Iceland's biggest tourist attractions: the Blue Lagoon, a vast outdoor lake which, even in March, greets bathers with the temperature of a hot bath.
There are supposed benefits from the silica rich water with its faint smell of sulphur, and the white silica mud is exported for health and beauty treatments.
Mr Albertsson told the BBC that he himself is a regular visitor.
"For me, the ideal time to take a dip is in the middle of winter, in the middle of the night, looking up at the stars and the Aurora Borealis, the Northern Lights."
Bulusan volcano still active!
Bulusan spewed ash clouds nearly 1.5 km into the sky on Tuesday night, its first major volcanic activity since similar explosions from November 1994 to January 1995.
"There is indeed abnormality and most likely this is a steam-driven explosion," Renato Solidum, director of the Philippine Institute of Volcanology and Seismology (Philvocs), said in a television interview.
"We can probably expect more explosions as a manifestation of this and more volcanic earthquakes," he said, adding that Philvocs was ready to raise its alert level if necessary.
"If ever we see signs that there is magma moving up the summit of the volcano, then we can raise the alert to a higher level."
The Institute issued an alert level of 1 in Bulusan on Sunday after detecting successive quakes. The highest alert level is 5, indicating lava flows or ash columns reaching 6 km.
Mild volcanic quakes were also felt and steam was seen coming from the crater of the 1,559-metre volcano in Sorsogon province early on Wednesday, Jaime Sincioco of the volcanology institute told Reuters.
Sincioco warned residents not to venture within the 4-km danger zone due to fears of sudden explosions.
Bulusan is one of six active volcanoes in the country monitored by government vulcanologists.
The Philippines lies on the Pacific Ring of Fire, a zone of frequent earthquakes and volcanic eruptions.
Mount Pinatubo, on Luzon island in northern Philippines, erupted in 1991 in the century's biggest blast, burying dozens of villages under tonnes of boiling mud after lying dormant for 600 years.
More than 800 people died in the wake of Pinatubo's eruption, mostly from diseases in overcrowded evacuation camps.
Thursday, March 23, 2006
Raoul Island is not done with volcanic activity
Scientists who flew over Raoul Island on Tuesday say the hydrothermal system under the island is showing signs of over-pressuring, and further eruptions cannot be ruled out.
“ From our aerial observations, it is clear that the heat, gas and water that are discharging into Green Lake are making this part of the volcano’s hydrothermal system unstable,” said GNS Science volcanologist Bruce Christenson.
Several new steam vents had opened in and around Green Lake during the eruption and some old ones had reactivated. Many of these have since been drowned as Green Lake has risen more than seven metres since last Friday’s eruption.
Dr Christenson was one of two volcanologists from GNS Science who joined DoC and airforce personnel on a RNZAF Orion reconnaissance flight over the island on Tuesday.
“One explanation for the increased hydrothermal activity is that it is being driven by the intrusion of magma at depth.”
Heightened activity is not confined to the lake. At Denham Bay, on the western side of the island, there is evidence of hot fluids seeping into the sea along the 2.5km-long beach.
The seepage was causing a milky discolouring of the seawater. This observation indicates that hydrothermal fluids under parts of the island are now rising to shallower levels in the volcano than in the recent past.
“ Everything we saw during the aerial surveillance suggests that last Friday’s eruption was hydrothermal in nature, originating from a reasonably shallow source beneath Green Lake.
“ Whether this is pre-cursory to magmatic events to come is not clear at this time, but with Green Lake continuing to rise and multiple steam vents remaining active, the probability of further hydrothermal eruptions is high.”
Volcanic debris blanketing parts of the island is largely made up of rocks and mud ejected from the bottom of the lake and from nearby vents.
Seismic activity under the island has declined steadily during the past week. The seismometer on the island is currently recording between 20 and 30 earthquakes a day, which is significantly above the normal background level for Raoul Island.
Dr Christenson said the Green Lake crater should not be entered while the present level of activity continued. The volcanic alert level remains at 2.
Raoul Island is an active volcano that has erupted 15 times in the past 3600 years.
Phillippines' volcano still shows some activity
Mount Bulusan spewed 1.5-kilometer-high ash columns into the sky at 10:58 p.m. Tuesday, the Philippine Institute of Volcanology and Seismology (Phivolcs) said. No one was reported hurt.
Jaime Sincioco, in charge of monitoring volcanoes at the government institute, said the activity was followed by three more separate phreatic explosions -- ash puffs caused by magma coming into contact with water.
"There is strong steaming activity," Sincioco said.
More eruptions were expected "in view of the volcano's recent reactivation" following volcanic quakes on Saturday, Phivolcs said in its bulletin on Wednesday.
The 5,115-foot volcano, located in Sorsogon province, 390 kilometers southeast of Manila, has been rumbling since Saturday.
The steam-driven explosion lasted for 20 minutes and was accompanied by four earthquakes, Phivolcs said.
“The explosion indicates there is abnormality,” Phivolcs director Renato Solidum told GMA Network’s “Saksi” newscast, adding very light ash falls were reported in several villages north, west and southwest of the volcano in the towns of Irosin and Juban.
"This recent ash explosion is more or less typical of Bulusan's activity during its restive period," Phivolcs said.
The explosion was accompanied by one explosion-type earthquake, and followed by three more explosion-type earthquakes recorded at 11:30 p.m., 11:32 p.m. and 11:37 p.m., Phivolcs said.
Very light ash falls poured down on the villages of Cogon, Tinampo, Gulang-Gulang and Bolos in Irosin; Puting Sapa and Bura-Buran in Juban; and some other villages in Sorsogon province.
Sincioco said the last time the volcano acted up in the same way was between November 1994 and January 1995.
He said volcanic ash was being collected to determine how deep inside the mountain it originated. Ground deformation also will be measured to discover whether fresh magma is rising.
The institute raised the five-stage alert level on the volcano from 0 to 1 to indicate "abnormality or unrest" after an increase in volcanic quakes, said Sincioco.
The agency warned people to stay away from areas within four kilometers from the crater.
Phivolcs has dispatched its Quick Response Team to augment the monitoring networks around the volcano. It has also raised alert level 1 in Bulusan, designating the four-kilometer radius around the volcano as permanent danger zone.
The PDZ is an area that should be off-limits to the public because this will be affected by sudden steam explosions.
Mount Bulusan has had 15 recorded eruptions. It last erupted in January 2005.
The Philippines is in the Pacific "Ring of Fire," where volcanic activity and earthquakes are common. In June 1991, Mount Pinatubo in the northern Philippines exploded in one of the world's biggest volcanic eruptions in the 20th century.
Back to the hot spot!
The quintet, accompanied by volcanologists from Geological and Nuclear Sciences (GNS), walked to Mount Moumouaki to view the eruption site and Green Lake on Wednesday morning.
Mr Kearney was taking the temperature of the crater lake when the eruption occurred and is presumed to have died.
DOC Warkworth area manager Rolien Elliot said Mr Kearney's five colleagues - Jim Livingstone, Morgan Cox, Melanie Nelson, Evan Ward and Lynda McGrory-Ward - wanted to see the scene for themselves.
"They needed to see first-hand the effects of the eruption and the changes to the crater and Green Lake, which is still rising," Ms Elliot said.
Photos released by DOC show the level of the lake has risen 8-10m since Friday. It has risen about 2m since Tuesday.
"There's a huge amount of hot water sitting in the lake," DOC spokeswoman Liz Maire told NZPA.
The DOC staff, along with police, volcanologists and searchers, arrived on Tuesday morning at Raoul Island, in the Kermadec Islands about 800km northeast of New Zealand, partly to look for Mr Kearney.
A recovery team got within 1.5km of the lake but could not go any further because it was too dangerous.
The Braveheart is expected to leave the island on Friday at the earliest. Ms Elliot said DOC would decide later in the week whether any of its staff would remain on the island.
She said the hostel the staff were based at had suffered no damage. Its generators, water and waste systems were working normally.
GNS volcanologist Brad Scott said the hostel area was very rarely touched by eruptions on the island.
"In the last 3600 years there have been 15 eruptions on Raoul and only on three occasions were they big enough to produce ash that has reached the site of the hostel."
Meanwhile, the tourist expedition ship Spirit of Enderby will leave Raoul Island on Wednesday without its passengers having landed on the island.
The passengers and crew had their permission to land revoked following the eruption and instead had to do with landing on nearby Meyer Island, close to the coast of Raoul Island, to watch seabirds.
Tuesday, March 21, 2006
Japanese volcano shows signs of volcanic activity
The Sapporo observatory said minor volcanic activity has been detected since around 6:28 a.m. on 1,499-meter Mount Meakandake.
Observatory officials added that they were able to confirm white smoke billowing out about 400 meters above the peak and blowing in a southeasterly direction at around noon.
Tuesday's eruption probably took place along the mountain's southwest slope, some 500 meters from the peak, officials said, adding that a new crater might have formed.
The volcano has seen small-scale eruptions many times in the postwar period. The last time it erupted was in November 1998, when a small amount of volcanic ash fell in an area up to 15 km east of the mountain.
Officials said the volcanic activity had subsided by 10:30 a.m., and there was no major change in seismic activity.
While they said there was little likelihood of a major eruption, they urged caution in the vicinity of the peak, saying small-scale eruptions could continue.
On March 11, the observatory detected volcanic seismic activity 576 times, a record since it began to observe the volcano in 1972.
Such activity, however, declined to 122 on March 12 and to 48 on March 13, leading the observatory to say no emergency measures were necessary.
Phillipine volcano erupts
No one was reported hurt when the 1,550-meter (5,115-foot) Mount Bulusan erupted at 10:58 p.m. (1458 GMT), the Philippine Institute of Volcanology and Seismology said.
The volcano -- located in Sorsogon province, 390 kilometers (244 miles) southeast of the capital, Manila -- had been rumbling in recent days.
“-This recent ash explosion is more or less typical of Bulusan’s activity during its restive period,” the volcanology agency said.
More eruptions were expected ¢in view of the volcano’s recent reactivation” following volcanic quakes on Saturday.
Light ash-falls were reported in several villages north, west and southwest of the volcano.
The agency warned people to stay away from areas within four kilometers (2.5 miles) from the crater.
The Philippines is in the Pacific ¢Ring of Fire,” where volcanic activity and earthquakes are common. In June 1991, Mount Pinatubo in the northern Philippines exploded in one of the world’s biggest volcanic eruptions in the 20th century.
Rescue mission on its way to recover scientist's body
It will take three days to reach the island, 1000km northeast of Auckland. A DOC spokesman said that the team would only land on the island if they decided it was safe, based on visual checks and updates on seismic activity. The party was expected to remain there for three or four days. Mr Kearney, aged 33, from Wellington, disappeared after a volcanic eruption on the island on Friday morning.
He left the staff quarters he shared with five other DOC workers for the hour-long walk to the volcano to check the water temperature in the crater lake. He had just reached the volcano when it erupted. "He was at the exact epicentre of the massive destruction, including where five metres of ash fell," Conservation Minister Chris Carter said yesterday. An initial ground search of the island by the other DOC staff and a thorough search by the Russian rescue helicopter sent from Tauranga failed to find any sign of Mr Kearney.
The remaining DOC staff -- team leader Jim Livingstone, and rangers Morgan Cox, Melanie Nelson, Evan Ward and Lynda McGrory-Ward -- were then evacuated from the island and flown to Auckland's Ardmore Airport. DOC spokeswoman Liz Maire said police had decided it would be a recovery mission rather than search and rescue, as the level of devastation indicated there was little chance of Mr Kearney surviving.
Michael Rosenberg is one of two GNS Science geologists who will assess the risk of further eruptions and whether it is safe for the group to land. The pair would maintain satellite phone contact with colleagues in New Zealand who were monitoring a seismometer on the island, he told the Sunday Star Times. They would not know if the eruption was a one-off until they had analysed eruption deposits. Mr Rosenberg said Friday's eruption "came out of the middle of nowhere". GNS Science had seen no sign of changes in recent months until last Sunday, when a swarm of small to moderate earthquakes began.
Meanwhile Ray Kearney recalled his last words to his son before he left for Raoul Island were "don't be a hero". Mr Kearney said his son had not been confirmed dead, but he knew there was little chance he had survived. His son dabbled in different careers -- architecture, forest and park management -- but always wanted to work outside, he told a national Sunday newspaper. As a 15-year-old, his son had convinced him to let him go solo on a tramp around the Tararua ranges, through Masterton and back down to Otaki.
The youngster took a mountain radio and called home every night. "I took a chance letting him go," he said. "But he had an incredible sense of direction... he always knew which way to go." At 16, he went with mountaineers Rob Hall and Gary Ball to Base Camp on Mt Everest, where he helped clear rubbish. He planned to save all his wages while on Raoul, and had talked about travelling to Europe. Friends yesterday paid tribute to a man remembered for his love of the outdoors and conservation.
Saturday, March 18, 2006
Lack of monitoring of Alaskan volcanoes could threatens traveller's safety
Without such ground-based monitoring, confirmation of an eruption can take hours, according to James Quick of the U.S. Geological Survey, who testified before a panel of the Senate Commerce Committee on Thursday. A delay of hours could be fatal when jets filled with people travel the skies at eight miles per minute, he said.
Such monitoring requires money, however.
John Eichelberger, a University of Alaska Fairbanks volcanology professor, told the committee, "adequate funding" is "the immediate challenge" for the Alaska Volcano Observatory. The observatory, where Eichelberger serves as coordinating scientist, monitors 30 volcanoes along Alaska's gulf coast and the Aleutian Islands.
The observatory needs a modest increase in funding, Eichelberger said, but just as necessary is a more stable funding system.
Congress sends about half the observatory's money to the Federal Aviation Administration, which sends it to the Department of Commerce, which sends it to the U.S. Geological Survey, Eichelberger said.
"This cumbersome process precludes long-term planning," he said.
In the current fiscal year, the observatory received $4.4 million through the U.S. Geological Survey's Volcano Hazards Program, as requested by the Bush administration. But that money can't be spent to deal with threats solely to aviation, Eichelberger said.
So Sen. Ted Stevens, R-Alaska, added another $3 million as an earmark to deal with ash hazards to aircraft. That's the money that went through the FAA first.
Stevens, chairman of the Commerce Committee, observed that Alaskans are dealing with a volcanic hazard right now.
"Over half the population of Alaska lies within 200 miles of Augustine (Volcano)," Stevens said Thursday. "And two months ago, it spewed ash throughout Southcentral Alaska, shutting down airports throughout the area."
This week, scientists said the volcano began oozing lava, although it showed fewer signs of explosive activity than it did in January.
At Thursday's hearing, Eichelberger, Quick and Terry McVenes, air safety chairman of the Air Line Pilots Association, all described past encounters between jets and volcanic ash:
* In 1982, a Boeing 747 with 240 passengers hit an ash cloud over Indonesia. All four engines quit and it fell from 37,000 feet to 12,000 feet before the crew restarted three engines and landed safely in Jakarta.
* Weeks later in the same area, another 747 experienced a nearly identical problem, though one engine stayed on and the crew was able to start another. It landed on two engines.
* In 1989, another 747 hit an ash cloud from Redoubt Volcano near Anchorage. It lost all power and electronics. Again, the crew was able to restart the engines and land.
Volcanic ash is not like wood or paper ash, Quick said. It's sand, silt and glass. When this type of ash enters a jet engine, some of it melts, but the melted material then solidifies on cooler parts of the engine, causing them to fail.
The grit also abrades turbine engine fans, windscreens and the fuselage. And it can short out electronic gear.
With improved warning systems, Quick said, ash hasn't caused an engine failure on a multi-engine aircraft since 1991.
The risk is still high over the Aleutians, though, he said.
"More than 200 flights carry roughly 25,000 people over northern Pacific air routes on a daily basis," he said in written testimony.
Eichelberger said the Aleutian chain may seem remote to most people, but it is not to international aviators.
"A remote place is far from home and usually at the corner of a map," he said. "But Earth does not have corners. It surprises people to discover that flights between East Asia and North America pass over Alaska, not Hawaii."
Quick said a recent USGS report identified the 19 volcanoes that seriously threaten aviation but have no ground monitors. The report described the monitoring needs posed by the 169 geologically active volcanoes in the country.
To prevent aviation problems, "real-time 24-7 eruption reporting is necessary" in dangerous volcanoes, Quick said.
"Our goal is that an observatory shall notify the appropriate regional air traffic center of an ash-producing eruption within five minutes of the start of the event," he said.
Ash is monitored using satellite images, and its movement is forecasted with weather models. In some cases, portable ground-based radar may be necessary, Quick said.
To illustrate the continuing high risk, Quick described the 2003 eruption of the Anatahan volcano in the Mariana Islands.
"Hours elapsed from the eruption's onset to the issuance of the first warning to aviation of ash in the atmosphere," he said.
With ground monitoring and other systems in place, eruptions can now be forecast anywhere from hours to days in advance, Quick said.
The USGS, for example, issued a bulletin on Jan. 10 warning that Augustine volcano in southern Cook Inlet could blow within the next few weeks. It erupted the next day, interrupting aviation across southcentral Alaska.
The USGS, UAF and the state of Alaska's Division of Geological and Geophysical Surveys all contribute to operating the Alaska Volcano Observatory.
Scientist left behind on New Zealand island which faces the fury of its volcano!
The chopper - modified to make a prolonged flight across the ocean - was carrying the five New Zealand Department of Conservation workers from Raoul Island to Auckland.
The return journey is 10 hours and 2,000km-long.
The rescuers were unable to search for the missing man, who failed to return from an excursion when one of the volcano's craters erupted on Friday morning, spewing steam, ash and boulders in the air.
The volcano blew its top at 8.21am (0621 AEDT) while the man was away from the rest of the group monitoring water temperature in a crater lake.
A moderate earthquake heralded the 40-second eruption.
Two workers later tried to find their colleague but were forced to retreat to a safer area because of the volcano's fury.
Fallen trees and ash blocked a track the man had taken, said departmental area manager Rolien Elliot.
The three women and two men took shelter at the island's hostel until the helicopter arrived around 6pm (1600 AEDT) and left an hour later after refuelling.
Helicopter pilot John Funnell said the blast had considerably altered the island's landscape.
"There's been about five hectares of native bush cleared and a lot of mud and evidence of boulders and rocks that have been thrown out of the crater itself," Funnell told Television New Zealand.
He said the eruption had been a frightening experience for the rescued workers.
The six people had been the only inhabitants of Raoul Island, part of the Kermadec islands - NZ territory located roughly halfway between Auckland and Tonga.
Elliot said the department was liaising with NZ's National Rescue Coordination Centre about the possibility of a follow-up search and rescue mission.
A police officer on board the helicopter was charged with assessing the feasibility of such a mission and reporting back to the centre, she said.
The MIL17 helicopter was accompanied by a Navajo fixed-wing aircraft, which flew over the island to survey the impact of the eruption.
It was expected to arrive at Auckland's Ardmore Airport around midnight (2200 AEDT).
Clusters of earthquakes occurred on Raoul from Sunday night through to Tuesday but then seismic activity dropped off until Friday.
Raoul Island is roughly triangular in shape with an area of 29 sq km, and has three craters.
The island is known to have erupted 14 times, most recently in 1964.
Augustine volcano still active!
Increased levels of carbon dioxide in emissions has led geologists to believe recent seismic activity is linked with dome building, rather than violent eruptions, the Anchorage (Alaska) Daily News reported Thursday.
Scientists say the volcano is producing magma, but they say that doesn`t necessarily mean explosions are imminent.
'Sometimes it comes out violently and sometimes it oozes out like a tube of toothpaste,' Peter Cervelli, a U.S. Geological Survey geophysicist with the Alaska Volcano Observatory, told the newspaper. 'And that`s what it`s doing right now.'
The volcano is located about 120 miles south of Anchorage and about 70 miles west-southwest of Homer, Alaska.
Officials are considering expeditions to Mount St.Helens' crater!
Soon, adventure-seekers may be able to do just that at Mount St. Helens. A year and a half after the volcano stirred to life in September of 2004, U.S. Forest Service officials are deciding whether to reopen the volcano to climbers.
"The public is interested," said Tom Mulder, manager of the Mount St. Helens National Volcanic Monument. "It's a recreation niche, a learning opportunity, and we want to serve the public well."
Forest officials in February began accepting conditional climbing reservations, which would enable permit-holders to scale the mountain from the main staging route at Climber Bivouac. Mulder, in an interview Tuesday, cautioned that he and Gifford Pinchot National Forest Supervisor Claire Lavendel haven't yet decided whether to reopen the climbing route, but permit-seekers are being advised that the traditional starting date of the climbing season is May 15.
During the busy summer climbing season, the Forest Service has historically capped the number of permits at 100 per day; half by reservation and half available by lottery each evening at Jack's Restaurant and Store on state Highway 503 in Ariel.
Scientists detected the first of thousands of tiny earthquakes beginning in the early morning of Sept. 23, 2004. Three days later, with larger quakes signalling that magma was on the move, Forest Service officials closed hiking trails above 4,800 feet on the mountain because of the danger of sudden steam explosions blasting rock out of the crater. Officials said at the time that they didn't want climbers exposed to a sudden gas or steam explosion while peering over the crater rim.
A week later, when seismologists detected an ominous tremor lasting for nearly an hour beneath the volcano, forest officials hastily evacuated thousands of visitors from the Johnston Ridge Observatory five miles north of the mountain.
The volcano has been erupting continuously since then, pumping out the equivalent of a pickup truck load of lava every second.
Despite several spectacular steam and ash blasts, including one a year ago that expelled a towering cloud to an elevation of 36,000 feet, none of the blasts have expelled rocks beyond the crater itself. Aptly known as ballistics, these rocks present the most direct hazard from any unexpected volcanic outburst.
"Climbers will be taking on the responsibility for exposing themselves to any risk that they may encounter," Mulder said. "Temperature extremes, to slippery slopes, to things that may fall out of the sky."
Tom Pierson, a geologist with the U.S. Geological Survey in Vancouver, tentatively plans to lead a guided hike to the crater rim in August. The climb, offered through the nonprofit Mount St. Helens Institute, will provide a radically different view from the pre-2004 landscape.
Massive mounds of fresh lava now cover the area where a smooth glacier had accumulated between the steep south crater wall and the 876-foot-tall lava dome that emerged in a series of eruptions during the 1980s.
"It will be great to see the new view and to take pictures to compare," Pierson said.
Scientists have watched carefully as the volcano has established a relatively placid pattern of dome-building over the past 18 months, and Pierson said it presents a fairly low hazard to the public. Because the volcano is part of the Gifford Pinchot National Forest, it's ultimately up to the Forest Service to decide whether to reopen the climbing route.
Capt. Chris Lynch, law enforcement officer at forest headquarters in Vancouver, said officers have cited only a handful of people who violated the closure zone around the volcano.
Mulder said that may be because the consequences of such violations are "painful," with a fine of up to $5,000 or six months in jail. Because interlopers above the timberline would be readily apparent to the many scientists and sight-seers flying around the volcano, law enforcement officers have ample opportunities to capture violators.
Lynch said officers easily collared one out-of-shape climber from the East Coast during the height of the volcano's international publicity in the fall of 2004.
"I hate to say it, but volcanoes do draw a certain level of people who wear aluminum foil on their heads," she said.
A little notoriety couldn't hurt, one local business booster said.
Stephanie Burhop, owner of Jack's Restaurant and the Cougar Store, said the area south of Mount St. Helens could use an economic boost from climbers converging on the area again.
"We're looking forward to it," she said. "Obviously, winters are very tough up here."
Erik Robinson covers the environment and energy for The Columbian. Reach him at 360-759-8014, or by e-mail at email@example.com.
Tuesday, March 14, 2006
Earthquakes could cause underwater volcanic eruptions
The committee says between March 9 and 12 it had detected 39 quakes ranging in magnitude from 4.0 to 5.3 on the Richter scale near the Andaman Islands, some 500 kilometres west of the southern Thai province of Ranong. The epicenter of the quakes was located 20 kilometers below the seabed, the same depth as the 2004 Indian Ocean earthquake which triggered the killer tsunami that left more than 220-thousand people dead in several countries.
But the committee says they are closely monitoring quakes and so far the government had no plans to issue an evacuation order.
Friday, March 10, 2006
Mount Vesuvius' next eruption could be dangerous for Naples
The discovery reported in this paper is the first volcanological and archaeological evidence that Vesuvius ever produced an eruption that strongly affected the area now occupied by metropolitan Naples, said co-author Michael F. Sheridan, UB Distinguished Professor in the Department of Geology, College of Arts and Sciences and director of the department's Center for Geohazards.
"We didn't know that the city of Naples would be so threatened," said Sheridan, a volcanologist and risk-analysis expert. "We never had evidence for a blast extending into the Neopolitan area and beyond it."
An eruption of this magnitude would cause devastating upheaval in socio-economic terms, Sheridan said, since the densely populated metropolitan area now is the largest in southern Italy.
He said that while there may not be a high probability that events like the Bronze-Age eruption or the eruption that buried Pompeii in AD 79 are going to occur in the near future, officials must still take those possibilities into account.
"There was this Bronze-Age eruption about 4,000 years ago, and then 2,000 years ago there was the AD 79 event. It seems that just about every 2,000 years, there's been a major eruption of this scale at Vesuvius," said Sheridan, who has studied all of the major eruptions at Vesuvius going back to the birth of the volcano 25,000 years ago.
"Using a standard statistical test, there is more than a 50 percent chance that a violent eruption will happen at Vesuvius next year," he said. "With each year that goes by, the statistical probability increases."
Based on archaeological findings, such as evidence of the abrupt abandonment of huts, as well as skeletons of people and livestock buried beneath more than one meter of pumice, the team members were able to reconstruct a chronology of what happened during the eruption.
Perhaps the most extraordinary finding was what the authors call "decisive proof of a massive exodus" from the area, demonstrated by the finding of thousands of human and animal footprints, embedded in the wet volcanic ash and leading away from the volcano.
The paper contends that most of the people who left probably survived because the early parts of the eruption consisted primarily of fallout of pumice, a light volcanic froth that forms during highly explosive eruptions and which often is not lethal in itself.
Nevertheless, the environmental damage, chiefly desertification, and the deposit of millions of cubic meters of ash and small pumice fragments likely occurred over thousands of square kilometers, making the area uninhabitable for decades at the very least and practically eliminating all socio-economic activities.
"This eruption is much larger than the ones that are currently anticipated at Vesuvius, like the eruption that occurred in 1631," said Sheridan. "However, such an event should be taken into account as a maximum probable-event scenario. Evacuation of 3 million people and their subsequent sporadic return could pose a real problem that must be carefully considered in the mitigation plans.
"The question is, 'Where do you put 3 million displaced people and for how long do they remain as evacuees?'" he asked.
Sheridan noted that as was the case after Hurricane Katrina, distribution of water, food and housing for the survivors and the nature of the escape routes also must be carefully considered with an evacuation of this magnitude.
"What must be taken into account are the temporary facilities where people could stay during the volcanic crisis to make sure that they are not located in zones that are too close to the volcano and where they could still be affected by the eruption," he said. "You certainly don't want to move people into the face of disaster."
Sheridan has spent four decades mapping hazards from active volcanoes in Italy, Mexico, Ecuador and around the world so that civil authorities know how and when to evacuate populations. He also serves on a U.S. Department of Energy expert panel to assess probabilistic volcanic hazards at Yucca Mountain, the planned ultimate repository for all of the United States' nuclear waste.
Last semester, Sheridan taught Geology 428/528, "Preventing Geologic Disasters," at UB. The course focused largely on Hurricane Katrina and assessed the lack of adequate mitigation planning and the tragic results as that disaster developed.
"There is a tendency to underestimate what geologists call the maximum probable event," said Sheridan. "It's politically negative to talk about the maximum probable hazard because you are purveying bad news and nobody in office wants to present this really bad news."
Wednesday, March 08, 2006
Is Italy well prepared for Mount Vesuvius eruption?
Italian plans call for the evacuation of 600,000 people from the city, but new assessments indicate more than three million people may be at risk, as past eruptions have caused destruction well beyond Naples.
Vesuvius is notorious for its eruption in 79 AD, which wiped the town of Pompeii off the map.
Modern plans to evacuate Naples are based on a similar-sized eruption that occurred in 1631.
The study, published by the U.S. National Academy of Sciences, shows that during the Bronze Age, the most recent eruption, ash-ridden lava flowed up to 16 miles to the northwest of the volcano, over and beyond what is modern Naples.
Anything within the first eight miles would have been swept away.
Ancient volcano eruption responsible for more than physical destruction of Pompeii
After the cataclysmic surges of lava finally subsided, the Avellino eruption blew what geologist Michael Sheridan and colleagues say was extremely hot ash to the edges of Naples some 25 kilometers away.Sheridan, who teaches at the University of Buffalo, says the discovery contradicts the belief by most scientists that Naples is safe from Vesuvius."I think this is really a major finding, finding up to three meters of ash that was traveling along the ground at hurricane velocities like the blast at Mount St. Helens," said Michael Sheridan. "It would be like the blast of Mount St. Helens occurring but having a city that was destroyed."
The St. Helens volcano, located in the northwestern state of Washington, erupted for nine hours straight in 1980 and claimed 57 lives.Like Pompeii, Sheridan, who studies volcanic hazards at the University of Buffalo in New York, says Avellino froze communities just the way they were at the time of the eruption.
Most striking are the homes that are perfectly preserved by the volcanic fallout, including eating utensils and food in bowls."And then the footprints," he said. "Thousands of footprints."While many people died of asphyxiation of hot gases, vulcanologist Michael Sheridan says most got away in time to save their lives."People as soon as they saw this drastic thing happening, they didn't grab anything," explained Sheridan.
"They just took off out of there."During the Bronze Age, the Naples region of Italy had been a hub of agriculture and trade. But Sheridan says the Avellino eruption completely wiped that out for 200 years.If history and science are any guide, Sheridan says his study shows Naples could be impacted by a massive Vesuvial eruption.
But he worries current disaster plans are not adequate to protect people who live in the volcano's shadow."Where would three million people go? And go where they would have to stay? They couldn't come back," he said. "And when would they go? They wouldn't want to go earlier than the cataclysm but there wouldn't be time if they waited until the last minute."
Tuesday, March 07, 2006
Small eruptions for Augustine!
The National Marine Weather Service says it expected ash to fall over the extreme southern end of Cook Inlet, ending very early today.
Earlier this month, scientists said pressure was building inside the volcano.
The volcano erupted in January. The ash plumes were six miles high and disrupted air travel.
Could extinct volcano become active again?
The bulge could also have awakened the Steamboat geyser besides forming new steam vents. Charles Wicks, a USGS scientist who worked on the study that appears in Thursday's edition of the journal Nature, admitted that the undersurface activities in Yellowstone Park remain a mystery, but that scientists had been able to understand a great deal about the Yellowstone caldera.The caldera is the collapsed volcano that is located in the center of the park.
The volcano last erupted 640,000 years ago. The northern rim of the caldera was discovered pretty recently and Wicks and his team used satellite images to monitor the swelling up of this area labeled as the North Rim Uplift Anomaly.
It was also noted that the caldera's floor moved down as the molten rock swelled. USGS findings prove that the unusual occurrences like the rise in temperatures began at around the same time. In 2003, the temperatures reached such a high level that officials closed some boardwalks for the fear that some people could burn themselves.
Additionally the Nymph Lake near Norris began showing new steam vents that spouted white clouds of gas. The Steamboat geyser burst open in May 2000 after staying silent for nine years. Subsequently there were five more eruptions between 2002 and 2003.Yellowstone's lead geologist Henry Heasler said that they were aware of the heaving caldera for quite sometime, "We've known that the caldera breathes," he said.
"Now we're starting to get a much better idea of those respirations." Heasler added that this research assumes significance in that volcanic activity can be predicted thus taking care of public safety.
Augustine getting full of steam
In reviewing GPS data, scientists have noted a two to three inch change in diameter since February 10, indicating that the volcano is once again swelling.
An eruption could happen again at anytime, but scientists say it would most likely be less powerful than the large eruptions that disrupted air traffic in January.
Monday, March 06, 2006
Augustine volcano could erupt again!
Scientists say an eruption could occur again, although it probably would be less explosive than the huge eruptions that disrupted commercial air travel in January.
Augustine is located 180 miles southwest of Anchorage.
Ancient village dug out
The explosions killed 117,000 people on the island, now part of Indonesia, and wiped out the tiny kingdom of Tambora, on the volcano's western flank. The avalanche of pumice and ash buried the town under three metres of debris, with only four of its estimated 10,000 residents surviving. "Events of this type will occur in the future, and we should be aware of what could happen," said Haraldur Sigurdsson, a geophysicist at the University of Rhode Island.
In an announcement on Monday at the university , a team of Indonesian and American scientists reported uncovering bronze bowls, ceramic pots, fine china, glass, and iron tools in gullies running through the jungle 25 kilometres from the volcano. Preliminary excavations exposed the carbonised framework of a house measuring about six metres by 10 metres. The log beams, even some of the bamboo siding and thatch roof, are charcoal black, but the original shape of the house is preserved. Skeletons of two adults lay where they died, one of them clutching a large knife.
"There's potential that Tambora could be the Pompeii of the East, and it could be of great cultural interest," Dr Sigurdsson said. The volcano is dormant, not dead. It has rumbled to brief life twice since 1815, mere burps compared with the destructive eruption that cost the mountain more than 1000 metres of its height, reducing its elevation to 2851 metres. The summit crater still smells of sulfur venting from the depths. Dr Sigurdsson said Indonesian archaeologists had examined the artefacts and were planning systematic excavations this year.
Their first impression of the material suggested that the Tamboran culture was linked by ancestry or trade to Vietnam and Cambodia.The many bronze pieces and historical evidence from Dutch and, briefly, British colonial days, Dr Sigurdsson said, supported the belief that Tamborans were "quite well off". Dr Sigurdsson and researchers from the University of North Carolina and the Indonesian Directorate of Vulcanology made the discovery in 2004 after a local guide told them of gullies where people were picking up strange objects.
A six-week survey with ground-penetrating radar showed the outlines of boulders, terraced fields, and the house. Spot excavations yielded more pottery and bronze, some bones and teeth, knives and a whetstone, even carbonised rice.
Mount Tambora has explosive history
The explosions killed 117,000 people on the island, now part of Indonesia, and wiped out the tiny kingdom of Tambora, on the volcano's western flank. A team of American and Indonesian scientists has now found remains of what it says is the "lost kingdom of Tambora."
In an announcement on Monday by the Graduate School of Oceanography of the University of Rhode Island, the scientists reported uncovering bronze bowls, ceramic pots, fine china, glass, and iron tools in gullies running through the jungle growth 15 miles from the volcano.
"There's potential that Tambora could be the Pompeii of the East, and it could be of great cultural interest," said Haraldur Sigurdsson, a geophysicist at Rhode Island who specializes in volcanoes. Other archaeologists have yet to assess the find.
Thursday, March 02, 2006
Super volcano underneath Yellowstone
A new model helps explain the latest episode of rapid surface rise and increased geyser activity—from 1997 to 2003—in the volcanically active region in the western United States.
Much of Yellowstone National Park lies in the crater of a massive volcano, formed in a landscape-altering eruption 640,000 years ago. The crater, or caldera, measures some 28 miles wide by 47 miles long (45 by 75 kilometers).
Subsequent lava flows—most recently 70,000 years ago—filled in much of the blasted-out crater, disguising the area's volcanic identity.
Since the 1970s scientists have known that the Yellowstone volcano remains highly active.
But the precise relationship between volcanic activity deep underground and Yellowstone's well-known network of geysers and other geothermal features has long been a puzzle for geologists.
Now a study by scientists with the U. S. Geological Survey (USGS) and the Yellowstone Volcano Observatory attributes changes in both surface terrain and geyser behavior to flows of magma, or molten rock, 9 miles (15 kilometers) below the Earth's surface.
"We're not sure yet if this is a normal episode or not," said Charles Wicks, a geologist at the USGS Western Region headquarters in Menlo Park, California.
Wrinkles and Cracks
Using satellite-based radar, Wicks and his colleagues were able to map small changes in surface elevation continuously across a wide area.
The new, detailed view of the Yellowstone crater shows a surface in constant motion, rising and falling in different locations and over fairly short intervals of time. From earlier surveys, scientists know that the caldera floor raised about 7 inches (18 centimeters) from 1976 to 1984 and then settled back about 5.5 inches (14 centimeters) from 1985 to 1995.
Researchers later noted a vertical rise in the crater floor, beginning in 1995. The floor largely began sinking again by 1998.
The new report, to be published in tomorrow's edition of the journal Nature, focuses on an isolated area along the north rim of the crater that continued to rise while the crater floor was sinking.
This localized uplift raised the ground level about 5 inches (13 centimeters) from 1997 to 2003.
"This was something new," Wicks said. "We had never seen uplift under the caldera rim before."
At the same time thermal activity in and around the Norris Geyser Basin, near the uplifting-rim area, began moving into high gear.
Steamboat Geyser, the world's largest, broke a nine-year silence with a series of eruptions from 2000 to 2003.
Park officials had to close some hiking trails due to increasing ground temperatures, and in 2003 a line of new steam vents appeared, roaring like jet engines.
Wicks and his colleagues believe that a pulse of volcanic magma moving horizontally underground caused the complex rippling of the land surface and the unusual hydrothermal displays.
A New Model
The researchers' theory is based on a mathematical model that helps explain the pattern of lifting revealed by the radar imaging.
The land's rise and fall over time, they say, can be attributed to variation in what may be a continuous flow of molten basalt. Basalt is cooled, hardened magma.
Wicks believes that in the 1997-to-2003 episode, an unusually large pulse of magma rose from deep underground and spread outward just beneath the caldera surface.
"As it spreads it looks for a way out," Wicks said. "A system of faults under the north rim provides a way for the magma to exit the caldera."
Outward movement of the magma pulse would cause the caldera floor to rise and then fall back, exactly as observed.
The continuing uplift of the caldera rim can be explained by the restricted size of the magma's exit route.
Wicks thinks a sort of underground bottleneck caused part of the north rim to continue rising. Forced through a narrowing passage, he says, the magma exerted a pressure that caused the rim to rise.
Uplift in this relatively confined area may have opened new underground passages for steam and superheated water, causing the unusual geyser activity.
"It's like bending a slab of clay. You see cracks form on the upper surface," Wicks said.
Park geologist Henry Heasler said that, while the new study is compelling, further tests of the model are needed.
"What they have nailed is that an intrusion from the caldera up to the Norris area matches the ground deformation pattern," Heasler said. "It's a fascinating paper, but there are still competing hypotheses."
For example, the surface changes may have been driven by flows of hot water and gas rather than magma.
Heasler said one way to test this would be by taking precise temperature measurements at the land surface, which he and others plan to carry out.
Discovery of an old city with a sad past!
Mount Tambora's eruption on April 10 1815 smothered villages on the island of Sumbawa with pumice, ash and rock, and claimed the lives of 90,000 people.
The impact of the blast was felt around the world. The volcano ejected more than 30 cubic kilometers of magma and thrust nearly 400 million tons of sulphur dioxide into the atmosphere, which caused a global cooling of nearly 1C, creating what volcanologists refer to as the "year without a summer".
Debris and ash from the eruption brought destruction to crops as far afield as North America, France and Germany. In Britain, fine particles suspended in the atmosphere created rich, vibrant skies for more than a year.
With the help of a local guide, scientists working on the island have unearthed the village of Tambora. Among sediments that date back to the eruption, they discovered ceramic pots, bronze bowls and the carbonised remains of a house with two occupants inside.
Inside, a woman was found in the kitchen, her hand next to some molten glass bottles. The house, which stood on wooden stilts with bamboo sides and a thatched roof, had been incinerated into charcoal by the fiery ash that is believed to have reached more than 500 Centigrade.
The remains of a second person were found outside what was probably the building's front door. Haraldur Sigurdsson, a volcanologist from the University of Rhode Island who is leading the dig, said the entire village, its occupants and culture were encapsulated beneath the ash, making the finding of great cultural significance.
The remains reveal how the village's 10,000 residents were probably wiped out within moments as the avalanche of hot volcanic ash, rock and gases, known as a pyroclastic flow, struck.
"We know that in an eruption such as that in 1815, that pyroclastic flows extend from the volcano in all directions to a distance of at least 40 kilometers [24 miles] radially and within that zone ... there is an extinction of all life," said Professor Sigurdsson.
The blast was six times more powerful than the eruption at Mount Pinatubo in 1991 and dwarfed that which destroyed the Roman town of Pompeii.
The civilization on Sumbawa island has intrigued researchers ever since Dutch and British explorers visited in the early 1800s and were surprised to hear a language that did not sound like any other spoken in Indonesia, Prof. Sigurdsson said. Some scholars believe the language was more like those spoken in Indochina. But not long after westerners first encountered Tambora, the society was destroyed. P> "The explosion wiped out the language. That's how big it was," Prof. Sigurdsson said. "But we're trying to get these people to speak again, by digging."
Artefacts uncovered at the site suggest that Tambora people may have had trade links with Indochina. Pottery uncovered nearby resembles that commonly found in Vietnam.
The dig will help volcanologists predict the potential dangers of volcanoes which remain active today. By feeding details from Tambora into computer models, they can estimate the lethal reach of those volcanoes should they erupt. "Events of this type will occur in the future, and we should be aware of what could happen," said Prof. Sigurdsson.
* Sixteen volcanoes around the world have been active in the past month, according to the University of North Dakota. Kilauea in Hawaii has been in a state of almost continuous eruption since 1983.
* Indonesia has 76 historically active volcanoes, more than any other country, and its total of 1,171 eruptions is only narrowly beaten by Japan's 1,274.
* Researchers believe the 1883 eruption of Krakatoa is still helping to keep the Earth cool and slow sea level rises.
Papua New Guinea has habitants fleeing
The volcano on tiny Manam island last erupted in October 2004, prompting the evacuation the following month of more than 9,000 people after heavy ash falls destroyed houses and food crops and contaminated water sources.
Islanders were relocated in camps on the PNG mainland's north coast opposite Manam but several hundred people have since returned to the island as volcanic activity subsided.
PNG's Volcanological Observatory in Rabaul on Tuesday reported a strong eruption from Manam's southern crater on Monday evening.
Eruptions continued into the night with black ash clouds rising up to 2km along with the ejection of glowing lava fragments and small rock and lava flows down the mountain.
The district administrator and three police officers visited the island on Tuesday to assess the situation and try to encourage islanders scattered in several villages around the mountain's base to leave.
Historical eruption uncovers a sad past!
The eruption of Mt Tambora in 1815 buried the Indonesian town of Tambora.
So much sulphur dioxide blasted into the atmosphere it triggered a global cooling.
The year, 1816, became known as "the year there was no summer".
In moments the volcano buried the 10,000 villagers on the Indonesian island of Sumbawa beneath 3m of volcanic ash and debris.
Another 107,000 people died elsewhere.
Scientists unearthing the village hope to learn how quickly volcanic eruptions can turn deadly. "Events of this type will occur in the future, and we should be aware of what could happen," said Haraldur Sigurdsson, a University of Rhode Island professor.
Two years ago, a team of scientists from the universities of Rhode Island and North Carolina and the Indonesian Directorate of Vulcanology began digging up the village.
They found Tambora with help from a local guide and in a mid-2004 dig discovered an entombed house with two people inside.
A woman was found in the kitchen, her hand next to glass bottles that had been melted by the ash flow. The house, on wooden stilts with bamboo siding and a thatched roof, had been incinerated into charcoal by the fiery ash that Prof Sigurdsson believes was at least 538C.
The eruption blew 200 times more magma and pulverised rock into the air than Mt St Helen's in the US state of Washington in 1980.
It sent sulphur dioxide 43km into the air.
The Tambora find was significant because it revealed the flow of hot volcanic ash, rock and volcanic gas extended in all directions for at least 40km "and within that zone . . . there is an extinction of all life", Prof Sigurdsson said.
Details of where the ash deposits fell are one factor that could reveal when relatively harmless fallout turned into a deadly ash flow.
Augustine volcano is about to go back to sleep!
She said the 4,134-foot mountain may be a little taller when the dome-building phase is complete.Seismic tremors from the island now indicate rockfall from unstable parts of the new dome, not deep magma movement, said Stephanie Prejean, a U.S. Geological Survey seismologist with the observatory.
These signals have decreased over the last few days, she said.Also slowing down is the pace at which the island has been deflating since the last big explosions, Prejean said. Five global positioning satellite sensors on the island began detecting inflation of the island last summer as magma moved into the core. By January, Augustine had swollen by about one inch.Then, two days after a series of explosions ended Jan. 28, the tumescent mountain began to subside.
An inch may not seem like a lot, but it’s indicative of forces working deep underground, Bull said. In any event, it’s the change that’s significant, not the amount of shift in the earth’s surface, she said.Augustine, located 75 miles southwest of Homer, first exploded Jan. 11 after weeks of growing seismicity. The mountain let off 13 explosive eruptions during the month.
If the eruption is in fact tapering off, that would make this year’s event smaller and less vigorous than the three previous eruptions, in 1963-4, 1976 and 1986, Prejean said.The 1964 eruption’s explosive phase continued for 11 months. The 1976 eruption, which dumped measurable ash onto Kenai Peninsula communities, fell quiet for several months, then returned with a second explosive period. The 1986 eruption had just one initial explosive phase, but it too was larger than this year’s.Comparing the patterns of earlier eruptions is difficult because they produced nothing like the wealth of data scientists harvested this year, Prejean said.
But the seismic buildup detected in previous eruptions helped alert scientists to the approach of magma last summer, giving them time to prepare their instruments, she said.‘‘I think this data set rivals any data set in the world,’’ she said. ‘‘It’s an amazing data set.’’Among the new technology deployed for Augustine were cameras (remote, thermal and infra-red), satellites and more frequent overflights. A low-light camera mounted on the Homer bluff has detected a glow on the island’s summit lately, providing evidence that dome-building continues.
Looking ahead, Prejean said she hoped the recent deployment of ocean-bottom seismometers in lower Cook Inlet will allow scientists to measure the location of magma inside the mountain using a system called seismic tomography. Describing it as a kind of MRI of the mountain, Prejean said the technique looks for magma by measuring the velocity and flow of seismic waves through the volcano.Augustine remains at alert-code color orange while the eruptive dome-building continues, the observatory said Friday.
Meanwhile this week, the observatory downgraded Spurr Volcano west of Anchorage from code yellow to code green, the lowest level for a dormant volcano. Growing seismicity had prompted an increase to yellow in July 2004 on Spurr, which last erupted in 1992. But the seismicity started tapering off last June.Scientists had been paying special attention to a meltwater lake in the ice on the summit of Mount Spurr, which was the source of occasional roiling gas emissions.
A recent change in color of the lake water indicates reduced acidity and, along with a decline in gas emissions, helped prompt the color-code change, the observatory said.At the same time, the observatory upgraded Korovin Volcano in the remote Aleutians to code yellow. Sensors on the Atka Island mountain picked up four recent days of increased seismicity, the observatory said.