A erupção pliniana do Pinatubo, que afetou significativamente o clima da Terra, começou há 35 anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

      

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.

   

       

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O vulcanólogo David A. Johnston morreu há 46 anos: Vancouver! Vancouver! This is it!

The last picture ever taken of Johnston, 13 hours before his death at the eruption site

 

David Alexander Johnston (Chicago, December 18, 1949 – Mount St. Helens, May 18, 1980) was an American United States Geological Survey (USGS) volcanologist who was killed by the 1980 eruption of Mount St. Helens in the U.S. state of Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post six miles (10 km) away on the morning of May 18, 1980. He was the first to report the eruption, transmitting "Vancouver! Vancouver! This is it!" before he was swept away by a lateral blast; despite a thorough search, Johnston's body was never found, but state highway workers discovered remnants of his USGS trailer in 1993.

Johnston's career took him across the United States, where he studied the Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers. After his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work, and that of fellow USGS scientists, convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area; their work saved thousands of lives. His story became intertwined with the popular image of volcanic eruptions and their threat to society, and a part of volcanology's history. To date, Johnston, along with his mentee Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption.

Following his death, Johnston was commemorated in several ways, including a memorial fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and another on the ridge where he died. Johnston's life and death are featured in several documentaries, films, docudramas and books. A biography of his life, A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, was published 2019.

 

 

 Johnston using a correlation spectrometer, which measures ultraviolet radiation as an indicator of the sulfur dioxide content of gases ejected from Mount St. Helens (photographed on April 4, 1980)

 

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O vulcão do Monte Santa Helena teve forte erupção há 46 anos...

  

O Monte Santa Helena (em inglês Mount St. Helens) é um vulcão ativo que fica no sudoeste do estado norte-americano de Washington, 154 quilómetros a sul de Seattle e a 80 a nordeste de Portland.

Após 127 anos de inatividade o vulcão entrou violentamente em erupção no dia 18 de maio de 1980, às 08.32 horas, locais (hora do Pacífico), matando 57 pessoas e ferindo muitas outras.

Após um tremor de terra de magnitude 5,1 na escala de Richter, o lado norte do monte entrou em violenta erupção, provocando danos ambientais numa área de 550 km². A cinza emanada da erupção provocou problemas respiratórios nos habitantes até 1.550 quilómetros de distância do vulcão.

Como resultado da explosão a altura da cratera do vulcão diminuiu cerca de 400 metros, passando de 2.950 para 2.549 metros, e teve a sua largura aumentada de cerca de dois quilómetros.

  

Tectónica de Placas dos vulcões da Cordilheira das Cascatas

   

in Wikipédia

 

In 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Washington, in the United States. The eruption (which was a VEI 5 event) was the only significant one to occur in the contiguous 48 US states since the 1915 eruption of Lassen Peak in California. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on Mount St. Helens' north slope.
Prior to the eruption, USGS scientists convinced local authorities to close Mount St. Helens to the general public and to maintain the closure in spite of pressure to re-open it; their work saved thousands of lives. An earthquake at 8:32:17 a.m. PDT (UTC−7) on Sunday, May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so fast that it overtook the avalanching north face.
An eruption column rose 80,000 feet (24,400 m) into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980.
Fifty-seven people (including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston) perished. Hundreds of square miles were reduced to wasteland causing over a billion U.S. dollars in damage ($2.74 billion in 2011 dollars), thousands of game animals killed, and Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service. The area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument.

   

    

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O vulcanólogo David A. Johnston nasceu há 76 anos...

The last picture ever taken of Johnston, 13 hours before his death at the eruption site

 

David Alexander Johnston (Chicago, December 18, 1949 – Mount St. Helens, May 18, 1980) was an American United States Geological Survey (USGS) volcanologist who was killed by the 1980 eruption of Mount St. Helens in the U.S. state of Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post six miles (10 km) away on the morning of May 18, 1980. He was the first to report the eruption, transmitting "Vancouver! Vancouver! This is it!" before he was swept away by a lateral blast; despite a thorough search, Johnston's body was never found, but state highway workers discovered remnants of his USGS trailer in 1993.

Johnston's career took him across the United States, where he studied the Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers. After his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work, and that of fellow USGS scientists, convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area; their work saved thousands of lives. His story became intertwined with the popular image of volcanic eruptions and their threat to society, and a part of volcanology's history. To date, Johnston, along with his mentee Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption.

Following his death, Johnston was commemorated in several ways, including a memorial fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and another on the ridge where he died. Johnston's life and death are featured in several documentaries, films, docudramas and books. A biography of his life, A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, was published 2019.

 

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A erupção pliniana do Pinatubo, que afetou significativamente o clima da Terra, começou há 34 anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

      

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

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David A. Johnston morreu há quarenta e cinco anos... (Vancouver! Vancouver! This is it!)

The last picture ever taken of Johnston, 13 hours before his death at the eruption site

 

David Alexander Johnston (Chicago, December 18, 1949 – Mount St. Helens, May 18, 1980) was an American United States Geological Survey (USGS) volcanologist who was killed by the 1980 eruption of Mount St. Helens in the U.S. state of Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post six miles (10 km) away on the morning of May 18, 1980. He was the first to report the eruption, transmitting "Vancouver! Vancouver! This is it!" before he was swept away by a lateral blast; despite a thorough search, Johnston's body was never found, but state highway workers discovered remnants of his USGS trailer in 1993.

Johnston's career took him across the United States, where he studied the Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers. After his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work, and that of fellow USGS scientists, convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area; their work saved thousands of lives. His story became intertwined with the popular image of volcanic eruptions and their threat to society, and a part of volcanology's history. To date, Johnston, along with his mentee Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption.

Following his death, Johnston was commemorated in several ways, including a memorial fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and another on the ridge where he died. Johnston's life and death are featured in several documentaries, films, docudramas and books. A biography of his life, A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, was published 2019.

 

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O vulcão do Monte Santa Helena teve uma erupção há 45 anos...

  

O Monte Santa Helena (em inglês Mount St. Helens) é um vulcão ativo que fica no sudoeste do estado norte-americano de Washington, 154 quilómetros a sul de Seattle e a 80 a nordeste de Portland.

Após 127 anos de inatividade o vulcão entrou violentamente em erupção no dia 18 de maio de 1980, às 08.32 horas, locais (hora do Pacífico), matando 57 pessoas e ferindo muitas outras.

Após um tremor de terra de magnitude 5,1 na escala de Richter, o lado norte do monte entrou em violenta erupção, provocando danos ambientais numa área de 550 km². A cinza emanada da erupção provocou problemas respiratórios nos habitantes até 1.550 quilómetros de distância do vulcão.

Como resultado da explosão a altura da cratera do vulcão diminuiu cerca de 400 metros, passando de 2.950 para 2.549 metros, e teve a sua largura aumentada de cerca de dois quilómetros.

  

Tectónica de Placas dos vulcões da Cordilheira das Cascatas

   

in Wikipédia

 

In 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Washington, in the United States. The eruption (which was a VEI 5 event) was the only significant one to occur in the contiguous 48 US states since the 1915 eruption of Lassen Peak in California. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on Mount St. Helens' north slope.
Prior to the eruption, USGS scientists convinced local authorities to close Mount St. Helens to the general public and to maintain the closure in spite of pressure to re-open it; their work saved thousands of lives. An earthquake at 8:32:17 a.m. PDT (UTC−7) on Sunday, May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so fast that it overtook the avalanching north face.
An eruption column rose 80,000 feet (24,400 m) into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980.
Fifty-seven people (including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston) perished. Hundreds of square miles were reduced to wasteland causing over a billion U.S. dollars in damage ($2.74 billion in 2011 dollars), thousands of game animals killed, and Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service. The area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument.

   

    

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A erupção pliniana do Pinatubo, que afetou significativamente o clima da Terra, começou há 33 anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

      

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

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Vancouver! Vancouver! This is it! - David A. Johnston morreu há quarenta e quatro anos...

The last picture ever taken of Johnston, 13 hours before his death at the eruption site

 

David Alexander Johnston (Chicago, December 18, 1949 – Mount St. Helens, May 18, 1980) was an American United States Geological Survey (USGS) volcanologist who was killed by the 1980 eruption of Mount St. Helens in the U.S. state of Washington. A principal scientist on the USGS monitoring team, Johnston was killed in the eruption while manning an observation post six miles (10 km) away on the morning of May 18, 1980. He was the first to report the eruption, transmitting "Vancouver! Vancouver! This is it!" before he was swept away by a lateral blast; despite a thorough search, Johnston's body was never found, but state highway workers discovered remnants of his USGS trailer in 1993.

Johnston's career took him across the United States, where he studied the Augustine Volcano in Alaska, the San Juan volcanic field in Colorado, and long-extinct volcanoes in Michigan. Johnston was a meticulous and talented scientist, known for his analyses of volcanic gases and their relationship to eruptions. This, along with his enthusiasm and positive attitude, made him liked and respected by many co-workers. After his death, other scientists lauded his character, both verbally and in dedications and letters. Johnston felt scientists must do what is necessary, including taking risks, to help protect the public from natural disasters. His work, and that of fellow USGS scientists, convinced authorities to close Mount St. Helens to the public before the 1980 eruption. They maintained the closure despite heavy pressure to re-open the area; their work saved thousands of lives. His story became intertwined with the popular image of volcanic eruptions and their threat to society, and a part of volcanology's history. To date, Johnston, along with his mentee Harry Glicken, is one of two American volcanologists known to have died in a volcanic eruption.

Following his death, Johnston was commemorated in several ways, including a memorial fund established in his name at the University of Washington to fund graduate-level research. Two volcano observatories were established and named after him: one in Vancouver, Washington, and another on the ridge where he died. Johnston's life and death are featured in several documentaries, films, docudramas and books. A biography of his life, A Hero on Mount St. Helens: The Life and Legacy of David A. Johnston, was published 2019.

 

in Wikipédia

O vulcão do Monte Santa Helena assustou-nos há 44 anos...

  

O Monte Santa Helena (em inglês Mount St. Helens) é um vulcão activo que fica no sudoeste do estado norte-americano de Washington, 154 quilómetros a sul de Seattle e a 80 a nordeste de Portland.

Após 127 anos de inactividade o vulcão entrou violentamente em erupção no dia 18 de maio de 1980, às 08.32 horas, locais (hora do Pacífico), matando 57 pessoas e ferindo muitas outras.

Após um tremor de terra de magnitude 5,1 na escala de Richter, o lado norte do monte entrou em violenta erupção, provocando danos ambientais numa área de 550 km². A cinza emanada da erupção provocou problemas respiratórios nos habitantes até 1.550 quilómetros de distância do vulcão.

Como resultado da explosão a altura da cratera do vulcão diminuiu cerca de 400 metros, passando de 2.950 para 2.549 metros, e teve a sua largura aumentada de cerca de dois quilómetros.

  

Tectónica de Placas dos vulcões da Cordilheira das Cascatas

   

in Wikipédia

 

In 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Washington, in the United States. The eruption (which was a VEI 5 event) was the only significant one to occur in the contiguous 48 US states since the 1915 eruption of Lassen Peak in California. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on Mount St. Helens' north slope.
Prior to the eruption, USGS scientists convinced local authorities to close Mount St. Helens to the general public and to maintain the closure in spite of pressure to re-open it; their work saved thousands of lives. An earthquake at 8:32:17 a.m. PDT (UTC−7) on Sunday, May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so fast that it overtook the avalanching north face.
An eruption column rose 80,000 feet (24,400 m) into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980.
Fifty-seven people (including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston) perished. Hundreds of square miles were reduced to wasteland causing over a billion U.S. dollars in damage ($2.74 billion in 2011 dollars), thousands of game animals killed, and Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service. The area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument.

   

    

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A erupção do Pinatubo, que afetou significativamente o clima da Terra, começou há 32 anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

      

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

in Wikipédia

O vulcão do Monte Santa Helena acordou há 43 anos

  

O Monte Santa Helena (em inglês Mount St. Helens) é um vulcão activo que fica no sudoeste do estado norte-americano de Washington, 154 quilómetros a sul de Seattle e a 80 a nordeste de Portland.

Após 127 anos de inactividade o vulcão entrou violentamente em erupção no dia 18 de maio de 1980, às 08.32 horas, locais (hora do Pacífico), matando 57 pessoas e ferindo muitas outras.

Após um tremor de terra de magnitude 5,1 na escala de Richter, o lado norte do monte entrou em violenta erupção, provocando danos ambientais numa área de 550 km². A cinza emanada da erupção provocou problemas respiratórios nos habitantes até 1.550 quilómetros de distância do vulcão.

Como resultado da explosão a altura da cratera do vulcão diminuiu cerca de 400 metros, passando de 2.950 para 2.549 metros, e teve a sua largura aumentada de cerca de dois quilómetros.

  

Tectónica de Placas dos vulcões da Cordilheira das Cascatas

   

in Wikipédia

 

In 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Washington, in the United States. The eruption (which was a VEI 5 event) was the only significant one to occur in the contiguous 48 US states since the 1915 eruption of Lassen Peak in California. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the volcano that created a huge bulge and a fracture system on Mount St. Helens' north slope.
Prior to the eruption, USGS scientists convinced local authorities to close Mount St. Helens to the general public and to maintain the closure in spite of pressure to re-open it; their work saved thousands of lives. An earthquake at 8:32:17 a.m. PDT (UTC−7) on Sunday, May 18, 1980, caused the entire weakened north face to slide away, suddenly exposing the partly molten, gas- and steam-rich rock in the volcano to lower pressure. The rock responded by exploding a hot mix of lava and pulverized older rock toward Spirit Lake so fast that it overtook the avalanching north face.
An eruption column rose 80,000 feet (24,400 m) into the atmosphere and deposited ash in 11 U.S. states. At the same time, snow, ice and several entire glaciers on the volcano melted, forming a series of large lahars (volcanic mudslides) that reached as far as the Columbia River, nearly 50 miles (80 km) to the southwest. Less severe outbursts continued into the next day only to be followed by other large but not as destructive eruptions later in 1980.
Fifty-seven people (including innkeeper Harry R. Truman, photographer Reid Blackburn and geologist David A. Johnston) perished. Hundreds of square miles were reduced to wasteland causing over a billion U.S. dollars in damage ($2.74 billion in 2011 dollars), thousands of game animals killed, and Mount St. Helens was left with a crater on its north side. At the time of the eruption, the summit of the volcano was owned by the Burlington Northern Railroad, but afterward the land passed to the United States Forest Service. The area was later preserved, as it was, in the Mount St. Helens National Volcanic Monument.

   

    

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A erupção do Pinatubo, que afetou significativamente o clima da Terra, começou há 31 anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

    

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

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Uma erupção do Pinatubo afetou significativamente o clima em toda a Terra há trinta anos

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

    

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

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Começou há 29 anos uma erupção que afetou significativamente o clima em toda a Terra

The eruption column of Mount Pinatubo on June 12, 1991, three days before the climactic eruption

    

Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.

The volcano's Plinian/Ultra-Plinian eruption on June 15, 1991, produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsula. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits causing extensive destruction to infrastructure and altering the river systems months to years after the eruption.

The effects of the eruption were felt worldwide. It ejected roughly 10,000,000,000 tonnes  or 10 km³ of magma, and 20,000,000 tonnes of SO2, bringing vast quantities of minerals and metals to the surface environment. It injected large amounts of particulate into the stratosphere – more than any eruption since that of Krakatoa in 1883. Over the following months, the aerosols formed a global layer of sulfuric acid haze. Global temperatures dropped by about 0.5 °C and ozone depletion temporarily increased substantially.
    

in Wikipédia