HAZARDOUS EARTH
SYNOPTIC LINKS
, EARTH’S LIFE SUPPORT SYSTEMS
HOW TECTONIC HAZARDS INFLUENCE THE CARBON CYCLE
VOLCANIC ERUPTIONS Eruptions release carbon dioxide into the atmosphere which has been stored dissolved in the mantle
- This increases the atmospheric carbon store
Eruptions release lava which cools into bare rock. This is vulnerable to weathering and further breakdown into the soil and atmospheric carbon stores
Explosive eruptions are less frequent so may have less influence on the carbon cycle but can emit more material than effusive eruptions
Submarine volcanoes release dissolved carbon dioxide into the ocean
Eruptions can damage or destroy biomass on volcano slopes
- Leads to a loss of accumulation of carbon in biomass and a release of carbon into the atmosphere upon burning
Eruption can deposit carbon rich ash, which increases biomass growth and the store of carbon in vegetation
Acid rain causes increased weathering of carbonate rocks releasing carbon into the atmosphere
EARTHQUAKES Earthquakes can cause forests to be felled
- This reduces the net primary productivity of the local carbon cycle
- Reduces carbon store in the vegetation in the local carbon cycle
HOW VOLCANIC HAZARDS INFLUENCE THE WATER CYCLE
VOLCANIC ERUPTIONS Volcanic eruptions cause jokulhlaups
- During an eruption, vast quantities of water accumulate until they find an exit from under the ice. This results in a torrent of water, and lava avalanching into the sea
- This significantly decreases the water stored in the cryosphere and increases the process of melting
Tsunamis associated with explosive eruptions
- A wide variety of volcanic processes can produce tsunamis. This includes volcanic earthquakes, caldera collapse, explosive submarine eruptions, the effects of pyroclastic flows and
lahars on water, and lava avalanching into the sea
- The violent eruption of some island volcanoes can cause massive displacement of ocean water and tsunami waves
, HOW THE WATER CYCLE INFLUENCE THE MANAGEMENT OF TECTONIC HAZARDS
VOLCANIC ERUPTIONS Lahars and jokulhlaups make the area difficult to access, thus inhibiting post event management
Aid can be delivered by boat if the volcanic eruption takes place near ocean (water store)
- After the Mt Etna eruption, a ship equipped with a medical clinic aboard was positioned off Catania, to the south of the volcano, to be ready in case of an emergency
EARTHQUAKES Aid can be delivered by boat if the earthquake takes place near ocean (water store)
Avalanches can inhibit rescue operations
- The Avalanche after the Nepal Earthquake meant that many people were stranded at camps at higher elevations since secure descent routes down the mountain were lost
HOW IMPACTS OF SEISMIC ACTIVITY ARE WORSENED BY THE WATER CYCLE
VOLCANIC ERUPTIONS - Formation of Lahars
INFLUENCE OF STORES Increases the death toll and inhibits the recovery process
Lahars are a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris, and water
Causes:
- Pyroclastic flows quickly melt large quantities of snow and ice (occurs when volcanoes are situation near water stored in the cryosphere)
- Lava can erupt from open bents and mix with wet soil, mud, or snow on the slope of the volcano to make a very viscous, high energy lahar
In 1985, the volcano Nevaro Del Ruiz erupted in central Colombia. Pyroclastic flows melted the mountain’s glaciers, sending 4 enormous lahars down its slopes. The lahars engulfed
the town of Armero, killing more than 20,000 people
Formation of jokulhlaups
Increase death toll, inhibits recovery process
During an eruption, vast quantities of water accumulate until they find an exit from under the ice. This results in a torrent of water, and lava avalanching into the sea
Occurs when the volcano is in close proximity to glaciers (water stored in the cryosphere)
Tsunamis associated with explosive eruptions
- A wide variety of volcanic processes can produce tsunamis. This includes volcanic earthquakes, caldera collapse, explosive submarine eruptions, the effects of pyroclastic
flows and lahars on water, and lava avalanching into the sea
- The violent eruption of some island volcanoes can cause massive displacement of ocean water and tsunami waves
The tsunamis created by the eruption of Krakatoa in 1883 are believed to have drowned 36,000 people
VOLCANIC ERUPTIONS - Lahars caused by the mixing of precipitation with volcanic material
INFLUENCE OF FLOWS After the Mt Merapi eruption, heavy rainfall mixed with pyroclastic flow material in the Magelang district led to a lahar that flowed 26 kilometres away from the volcano
EARTHQUAKES - INFLUENCE OF Liquefaction
STORES Worsens damage to buildings (adds to economic impact), makes it difficult to access areas, leads to the collapse of slopes and river banks
When an earthquake strikes an area with surface materials of fine grained sands, alluvium and landfill with high water content, the vibrations can cause these materials to behave
