Post on 13-Jan-2016
Common types of magma eruptions
Shield volcanoVolcanic domeCinder conesComposite volcanoCalderaFissureFlood basalt
Mount St. Helens
Mount St. Helens in Washington is a composite volcano
On March 16, 1980 the first of a series of minor earthquakes occurred under the volcano
This marked the beginning of a new eruption cycle
It had been ~350 years since the last eruption
Mount St. Helens
On May 18, 1980, at 8:32 am, a magnitude 5.1 earthquake occurred 1 mile directly under the volcano
10 seconds later, the north side of the volcano began to collapse followed immediately by an explosion that blew the top 400 meters (1300 feet) off of the peak (a volume of 1.3 cubic kilometers)
Mount St. Helens
“...24 square miles of valley was filled by a debris avalanche, 250 square miles of recreation, timber, and private lands were damaged by a lateral blast, and an estimated 200 million cubic yards of material was deposited directly by lahars (volcanic mudflows) into the river channels”
“Fifty-seven people were killed”
Mount St. Helens Ash Fall
Mount St. Helens
Mount St. Helens is now a volcanic national monument and remains active
Volcanic Hazards
1815 Indonesia 92,000 killed
1822 Indonesia 5,500 killed
1826 Indonesia 3,000 killed
1883 Indonesia 36,417 killed
1902 Martinique 29,025 killed
1902 Guatemala 6,000 killed
1919 Indonesia 5,110 killed
1951 New Guinea 2,942 killed
1982 Mexico 1,700 killed
1985 Columbia 23,000 killed
How Bad Can It Be?
Causes of volcanic-related deaths Over the last 2,000 years
How Bad Can It Be?
Volcanic Bomb
Gases
Sulfur dioxide (SO2)Hydrogen sulfide (H2S) Carbon dioxide (CO2) Hydrogen Chloride (HCl) Hydrogen Fluoride (HF)
Volcanoes can also eject great quantities of gases and steam which can be mixed with the pyroclasts
Lava FlowsLava erupts from the flank of the Barcena Volcano on the Revillagigedo Islands, Mexico in the Pacific Ocean causing little damage
Lava FlowsLava set fire to the brand new Waha`ula Visitor Center in Hawai`i Volcanoes National Park when an 1989 eruption of Pu‘u ‘O‘o–Kupaianaha completely covered the area with thin pahoehoe lava flows
Lava Flows of Parícutin
The Parícutin eruption began as a fissure in a cornfield owned by farmer Dionisio Pulido on February 20, 1943 in the Mexican state of Michoacán
Pulido, his wife and son, all witnessed the initial eruption of ash and stones first-hand as they plowed the field
1902 Martinique
Martinique is an island formed by volcanoes in the Caribbean
It was a French colony
The dormant Mount Pelée volcano began a new series of eruptions on April 25, 1902
1902 MartiniqueWith each passing day, the eruptions became worse
The French governor refused to evacuate the city of St. Pierre and surrounding smaller cities at the base of the volcano
On Wednesday, May 7, 1902, the governor with his family and entourage visited St. Pierre
There was a gala ball that night
1902 Martinique
The next day at 8:02 am, the city of St. Pierre was destroyed by a pyroclastic flow that roared down the slopes of Mount Pelée at of 670 kilometers per hour (415 miles per hour)
1902 Martinique
Over 29,000 people are burned alive in seconds
The entire town was completely destroyed
2007 MartiniqueToday, Martinique is an overseas department of France and St. Pierre is a quaint tourist attraction
Mount Pele
Santorini
Santorini is a circular group of islands in the Aegean Sea and is part of Greece
The central lagoon is a volcanic caldera 12 by 7 kilometers (8 by 4 miles) in size
SantoriniAbout 3500 years ago there was a tremendous volcanic eruption
30 cubic kilometers of the island was blown as high as 36 kilometers into the atmosphere
This is believed to be the largest volcanic explosion in recorded human history
Atlantis?The eruption, ash fall and tsunamis are believed to have destroyed the Minoan civilization at the height of its wealth and power
This may be the source of Plato’s story of Atlantis
SantoriniAkrotiri is an ancient city on Santorini that was buried under hundreds of feet of volcanic ash from this tremendous explosion
It is an active archaeology dig that is open to the public
1950 Santorini
The volcano is still active and erupted in 1950
2009 Santorini
Today, Santorini is a major tourist attraction
Mount Tambora (or Tomboro) is an active stratovolcano on Sumbawa island, Indonesia
It was thought to be 14,000 feet (4,300 meters) high when it blew up in April 1815
The death toll was at least 71,000 people (some estimate 92,000 people were killed), of which 11,000 to 12,000 were killed directly by the eruption
Mount Tambora
The explosion was heard on Sumatra island 2,000 kilometers (1,200 miles) away
The red areas outlines the heavy ash fall
Mount Tambora
The eruption ejected immense amounts of volcanic dust into the upper atmosphere and created global climate anomalies in the Northern hemisphere
The entire world experienced dusty skies and deep red sunsets
Mount Tambora
(Dusty sunsets in Hong Kong from 1992 Mount Pinatubo eruption)
1816 became known as the Year Without a Summer and the Poverty Year and Eighteen hundred and Froze to Death
Agricultural crops failed and livestock died in much of the Northern Hemisphere, resulting in the worst famine of the 19th century
Year Without a Summer
Europe, still recuperating from the Napoleonic Wars, suffered from food shortages
Huge storms, abnormal rainfall with flooding of the major rivers of Europe (including the Rhine) are attributed to the event, as was the frost in August 1816
Year Without a Summer
Food riots broke out in Britain and France and grain warehouses were looted
The violence was worst in landlocked Switzerland, where famine caused the government to declare a national emergency