Gases that escape in the greatest abundance from volcanoes are:
-water vapor
-carbon dioxide
-hydrogen chloride
-nitrogen
-sulfur dioxide
Volcanic gases play an important role in the Earth System. Carbon dioxide, on the early earth, was emitted from volcanoes and converted to oxygen by photosynthetic algae.
Volcanoes & The Atmosphere
Volcanic activity gave the early Earth much of it’s atmosphere. (carbon dioxide and nitrogen).
Volcanoes & The Atmosphere
Water vapor is essential to the Earth system. Most of Earth’s surface water seems to have been released from the Earth’s interior by volcanoes.
Volcanoes & The Water Cycle
Volcanoes produced the atmosphere and the oceans
N2 CO2 H2O
Volcanic Emissions Flow Chart
N2 O2 oceans
99% of atmosphere
remains photosynthesis condensation
Volcanoes and the Earth System
Cosmos
High concentrations of carbon dioxide near a volcano are hazardous because they cause people and animals to suffocate.
Dangerous Gases
Lake Nyos - Cameroon
Lake Nyos - Cameroon
If the air that we breath has more than 10% CO2 it becomes deadly because it displaces the Oxygen that we need for respiration.
Lake Nyos, Cameroon, is a very deep lake within a volcanic crater.
The lake is so deep that hydrostatic pressure forces CO2 to remain at the lake bottom.
When the pressure of the CO2 exceeds a certain limit the gas rapidly bubbles up out of the lake and flows as an invisible gas cloud down the adjacent slopes.
On August 16, 1986 such a gas release flowed 19 km suffocating 1,700 people along its route.
Lake Nyos - Cameroon
Lake Nyos - Cameroon
Lake Nyos - Cameroon
The fountain lifts CO2 up to the surface so that it no longer accumulates.
Lake Nyos - Cameroon
Mammoth Mountain is a relatively young volcano that is emitting large volumes of CO2.
Gas concentrations in the soil in some areas near the mountain are high enough to kill trees and small animals.
Mammoth Mountain. California
Mammoth Mountain. California
Formation of acid rain (from sulfur dioxide SO2) can cause water contamination and plant damage Prevailing winds can blow gases thousands of kilometers away
Acid Rain
tropospheric aerosol cloud(lifetime 1 - 3 weeks)
large explosiveeruption(e.g. Tambora)
large effusiveeruption(e.g. Laki)
tropospheric cooling
stratospheric aerosol cloud(lifetime 1 to 3 years)
ashfall
stratospheric warming
reducedsolar flux
ballistics
SO2
SO2
H SO2 4
SO2
H SO2 4H S
2
incoming solar radiation
reflected andscatteredsolar flux
solar fluxabsorbed inthe infra-red
absorption ofupwardinfra-redflux
CO2
N2
H O2
Climatic Effects
Global Climate Change
SO2 (sulfur dioxide) in the upper atmosphere reduces incoming solar radiation.
SO2 from an eruption forms tiny droplets of sulfuric acid in the upper atmosphere.
The droplets significantly increase global albedo…..a negative radiative forcing that leads to cooling.
Mt. Pinatubo (1991) released 22 million metric tons of SO2 and reduced the Earth’s average temperature by 0.5 degrees Celsius in the year following the eruption.
• Largest known historic eruption → 200 Mt sulphate aerosol in stratosphere
• 1816 one of coldest northern hemisphere summers of last 600y
• Extreme weather – June snow in eastern North Am. – Summer killing frosts led to near total failure of crops in New England
– Europe Summer T 3ºC cooler than 1951-70 average • Cooling effect continued for 3 years • 1816-19 ‘last great subsistence crisis in western
world’ bread riots; famine; typhus & cholera
Tambora & ‘the year without a summer’
Tambora & ‘the year without a summer’
Global Surface Temperature Reconstruction
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Monitoring Volcanoes • Seismicity • Ground Movements
– Tiltmeter – GPS
• Visual Observations: – Gas Geochemistry – Water Temperature