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SANTIAGO, Chile — An erupting Chilean volcano sent a towering plume of ash across South America on Monday, forcing thousands from their homes, grounding airline flights in southern Argentina and coating ski resorts with a gritty layer of dust instead of snow.

Booming explosions echoed across the Andes as toxic gases belched up from a three-mile-long (five-kilometer long) fissure in the Puyehue-Cordon Caulle volcanic complex — a ridge between two craters just west of the Chilean-Argentine border that began erupting Saturday.

Winds blew a six-mile-high (10-kilometer-high) cloud of ash all the way to the Atlantic Ocean and even into southern Buenos Aires province, hundreds of miles to the northeast.

Authorities in Chile went house to house, trying to persuade stragglers near the volcano to leave because of an increasing danger of toxic gas and flash floods. By Monday, about 4,000 people had been evacuated from more than 22 communities. They began fleeing as swarms of earthquakes Saturday heralded the eruption and hundreds more fled Monday to shelters farther away.

Some refused to leave, wanting to protect their homes and livestock. Chile’s verdant lakes region is a center for dairy farming, with more than 9,000 cows and sheep.

Deputy Interior Minister Rodrigo Ubilla said about 50 families in the Rininahue area refused to abandon their homes.

“Everything is prepared with shelter and transportation for them to immediately leave the danger zone,” added Vicente Nunez, director of Chile’s emergency preparedness office, urging them to leave.

Just north of the complex of volcanoes, the city of Futrono and the communities of Lago Ranco and Entre Rios were particularly vulnerable to flash floods. Some people also refused to leave Mantilhue, along the Rio Bueno, or “Good River,” just six miles (10 kilometers) from the eruption. And while the evacuation order wasn’t yet mandatory, a group of Mapuche Indians said they would seek the regional governor’s authorization to enter the area to pray for the volcano to stop erupting.

Enrique Valdivieso, the director of Chile’s National Geology and Mines Service, said the fissure was belching toxic gases and material that could clog rivers and force them to overflow.

Spectacular displays of lightning flashed in the volcanic clouds during the weekend, and while the amount of ash falling east of the volcano subsided significantly by Monday, experts said it was too early to predict how long it will take before the volcano falls silent.

Volcanic dust coated ski slopes above San Carlos de Bariloche and Villa la Angostura two weeks before the official start of the winter skiing season. The resorts’ trade group said it was too early to say how it would affect the local economy, but for now, residents were told to stay indoors and tourists were asked not to come.

The Cordon Caulle is nearly 620 miles (1,000 kilometers) south of Santiago, in Chile’s lakes region, just west of Bariloche. Authorities went on alert before the eruption Saturday when as many as 240 tremors an hour struck the region.

The volcano’s last major eruption was in 1960, shortly after a 9.5 magnitude earthquake, the most powerful in recorded history, struck Chile.

Some scientists have said that last year’s 8.8 quake in Chile increased the likelihood of volcanic activity due to shifts in pressure along the Earth’s tectonic plates.

The ash cloud first blew over Argentina and then circled back over Chile on Sunday. By Monday, however, prevailing winds had spread the ash eastward as far as Bahia Blanca, in southern Buenos Aires province on the Argentine coast.

During the weekend, the volcano spat out pumice rocks nearly eight inches (20 centimeters) in diameter.

Because airborne ash can severely damage jet engines, all flights between Buenos Aires and the Andean resorts of Bariloche, Esquel and Chapelco were canceled until June 12. Seven other airports in Argentina were closed through Thursday, effectively isolating the southern Patagonia region from the rest of the country. Aerolineas Argentinas also cancelled nighttime flights well to the north of the volcanos, from Buenos Aires to Santiago, Chile, and Mendoza, Argentina, as a precaution.

LAN airlines suspended more than 35 flights from Chile to southern Argentina, and some highways in Argentina also were closed.

Across Argentina’s southern midsection, schools were closed, routine government work was suspended and elective surgery were canceled as well.

Also closed was the nearby border crossing of Cardenal Samore, where a twisting mountain road climbs through stunning arid valleys on the Argentina side before dropping through lush green forests and fields in Chile. Even when skies cleared in places Monday, the area was draped in an abrasive gray blanket.

The 11-mile-long (17-kilometer-long) Cordon Caulle rises 5,900-feet (1,800 meters) above sea level between the Pueyehue and Nevada volcanoes, above a connected complex of molten rock. Chile has more than 3,000 volcanoes along its Andean spine, and 500 of these are considered geologically active. About 60 Of these have erupted in the last 450 years.

http://www.washingtonpost.com/lifes...i-areas-in-ash/2011/06/06/AGJjAaKH_story.html
 

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:agree:
Love that piezo-electric effect.
Is it piezo-electric effect??? I thought it was static-electricity, that causes lightning. Piezo effect is caused by deforming certain crystals which causes them to give off a charge and if you add the charge to the crystal it will deform the crystal. How is that happening in this case?
 

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Is it piezo-electric effect??? I thought it was static-electricity, that causes lightning. Piezo effect is caused by deforming certain crystals which causes them to give off a charge and if you add the charge to the crystal it will deform the crystal. How is that happening in this case?
This is correct. Converting mechanical energy into electrical energy and vice versa-commonly called the piezo electric effect. Think of a microphone or ultrasonic transducer.
Not sure if this effect would be present here.
It's still damn cool though..
 

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I'm no expert, but wouldn't the mechanical effect of the volcanic eruption, produce the static charge that created the lightning? :huh:
 

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Is it piezo-electric effect??? I thought it was static-electricity, that causes lightning. Piezo effect is caused by deforming certain crystals which causes them to give off a charge and if you add the charge to the crystal it will deform the crystal. How is that happening in this case?
I'm no expert, but wouldn't the mechanical effect of the volcanic eruption, produce the static charge that created the lightning? :huh:
Piezo's are quartz crystals. When they are stressed, they produce an electrical charge. Conversley when they are subjected to a charge, they flex. Microphones (crystal elements), cheap phonograph needles (old victrola's :D), and mics in some cell phones all use piezo crystals to produce a charge. Piezo tweeters used in cheap stereo speakers are an example of using a charge to flex the crystal.

This stress of quartz and similar materials happens in volcanic eruptions also. It is part of the cause of the lightning that is viewed. I'm sure there is friction involved too.

Review of Electric and Magnetic Fields Accompanying Seismic and Volcanic Activity


From:
Rapid fluid disruption: A source for self-potential anomalies on volcanoes
M.J.S. Johnston, J.D. Byerlee, and D. Lockner
U.S. Geological Survey, Menlo Park, California

"Other mechanisms can of course generate substantial charge on, and particulaly above, volcanoes during violent eruptions and can have many consequences, including spectacular lightning. These shock mechanisms include piezoelectric effects [Finkelstien et al, 1973; Baird and Kennan, 1985]"

Full read here
 

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Piezo's are quartz crystals. When they are stressed, they produce an electrical charge. Conversley when they are subjected to a charge, they flex. Microphones (crystal elements), cheap phonograph needles (old victrola's :D), and mics in some cell phones all use piezo crystals to produce a charge. Piezo tweeters used in cheap stereo speakers are an example of using a charge to flex the crystal.

This stress of quartz and similar materials happens in volcanic eruptions also. It is part of the cause of the lightning that is viewed. I'm sure there is friction involved too.

Review of Electric and Magnetic Fields Accompanying Seismic and Volcanic Activity


From:
Rapid fluid disruption: A source for self-potential anomalies on volcanoes
M.J.S. Johnston, J.D. Byerlee, and D. Lockner
U.S. Geological Survey, Menlo Park, California

"Other mechanisms can of course generate substantial charge on, and particulaly above, volcanoes during violent eruptions and can have many consequences, including spectacular lightning. These shock mechanisms include piezoelectric effects [Finkelstien et al, 1973; Baird and Kennan, 1985]"

Full read here
Obviously, plenty of released mechanical energy exists in an event such as a volcanic eruption, so it does stand to reason that crystalline substances within the eruption would be subject to the piezoelectric effect and release electrical energy. It's very interesting for me to look at this phenomenon this way as piezoelectric crystals (quartz, lead zirconate titanate, lithium sulphate, etc.) are at the very heart of my profession (ultrasonics). As an instructor, it gives me another great example for students to understand this effect. I've never seen this used as an example in any of the training material for industrial ultrasonics. Just goes to show..you never know what you'll learn on Digital Corvettes!
 

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Damn, you all are some serious geeks. Nobody better not say anything about us computer guys! :laughing:
 
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