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Natural Hazards and Disaster
Lab 7: Question Sets 5: Volcanoes
Q-Set 5: Volcanoes
5.1 What are the main types of volcanoes and what are the main characteristics of eruptions for these types?
5.1 What are the main types of volcanoes and what are the main characteristics of eruptions for these types?
Three main types: • stratovolcanoes (or composite volcanoes): conical, consists of layers • cinder cone volcanoes: doesn’t have layers, steep conical hills • shield volcanoes: large shields.
Q-Set 5: Volcanoes
5.1 What are the main types of volcanoes and what are the main characteristics of eruptions for these types?
The volcano type depends on the type of magma and its viscosity: • Volcanoes above subduction zones extrude silicarich, iron-poor lavas that are very viscous and can
range widely in composition. • Basaltic lava is very fluid. • Mid-ocean ridge lava is predominantly basaltic.
Three main types: • stratovolcanoes (or composite volcanoes): conical, consists of layers • cinder cone volcanoes: doesn’t have layers, steep conical hills • shield volcanoes: large shields.
Q-Set 5: Volcanoes
Natural Hazards and Disaster
Plag et al., 2015
Q-Set 5: Volcanoes
5.2 What is a lahar and why are they dangerous?
Q-Set 5: Volcanoes
5.2 What is a lahar and why are they dangerous?
Rivers of tephra and water slurry, called lahars, are a danger to those who live near volcanoes.
Q-Set 5: Volcanoes
5.3 Briefly describe the impacts of a VEI 7 eruption that took place during the Holocene. You can select one of the following eruptions: Crater Lake (7696+-50 BP), Santorini (3629+-14 BP), or Mount Tamboro (1815).
Q-Set 5: Volcanoes
VEI 7 / M 7: - at least seven events in the Holocene - ~5% - 10% chance that this will happen in the 21st century - Will have very different impact than previously
Q-Set 5: Volcanoes
10
Tambora, 1815
Changbai, ~970Santorini, ~1610 BCCrater Lake, ~5680 BC
Kurile, ~5550 BC
Kikai, 2350 BCTaupo, 230
12 Billion by 2100
VEI 7 Eruptions
Q-Set 5: Volcanoes
5.4 Describe the process that caused the disaster of August 21, 1986 near Lake Nyos, Cameroon.
Q-Set 5: Volcanoes
August 21, 1986 Lake Nyos, Cameroon
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/05/sci_nat_enl_1127817614/img/1.jpg
before after
Q-Set 5: Volcanoes
August 21, 1986 Lake Nyos, Cameroon
Over 1,800 people and thousands of animals found asphyxiated
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/05/sci_nat_enl_1127817614/img/1.jpg
before after
Q-Set 5: Volcanoes
August 21, 1986 Lake Nyos, Cameroon
Over 1,800 people and thousands of animals found asphyxiated
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/05/sci_nat_enl_1127817614/img/1.jpg
before after
No property or vegetation damage
Q-Set 5: Volcanoes
August 21, 1986 Lake Nyos, Cameroon
Over 1,800 people and thousands of animals found asphyxiated
What happened?
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/05/sci_nat_enl_1127817614/img/1.jpg
before after
No property or vegetation damage
Q-Set 5: Volcanoes
http://img.youtube.com/vi/uFzz5c_Vvlk/0.jpghttp://i.ehow.com/images/GlobalPhoto/Articles/5259929/300px-DietCokeMentos-main_Full.jpg
dissolved CO2 under pressure is perfectly safe....
Q-Set 5: Volcanoes
http://img.youtube.com/vi/uFzz5c_Vvlk/0.jpghttp://i.ehow.com/images/GlobalPhoto/Articles/5259929/300px-DietCokeMentos-main_Full.jpg
dissolved CO2 under pressure is perfectly safe....
...but if too much CO2 or if something disturbs the equilibrium, get a sudden burst of gas release
Q-Set 5: Volcanoes
Q-Set 5: Volcanoes
Why here?
Q-Set 5: Volcanoes
Why here?
Q-Set 5: Volcanoes
Why here?
Q-Set 5: Volcanoes
Why here?
Lake Nyos, August 22 1986
Q-Set 5: Volcanoes
Why here?
Lake Nyos, August 22 1986
Q-Set 5: Volcanoes
Why here?
Lake Nyos, August 22 1986
Q-Set 5: Volcanoes
Why here?
Lake Nyos, August 22 1986
CO2 burst
Q-Set 5: Volcanoes
http://www.hprcc.unl.edu/nebraska/Lake_Nyos.jpg
Why here?
Lake Nyos, August 22 1986
CO2 burst
Q-Set 5: Volcanoes
http://www.hprcc.unl.edu/nebraska/Lake_Nyos.jpg lake bottom
Why here?
Lake Nyos, August 22 1986
CO2 burst
Q-Set 5: Volcanoes
http://www.hprcc.unl.edu/nebraska/Lake_Nyos.jpg
Sudden burst of dissolved CO2 from the bottom of Lake Nyos blanketed the area in deadly, odorless gas
lake bottom
Why here?
Lake Nyos, August 22 1986
CO2 burst
Q-Set 5: Volcanoes
Question Set 5: Volcanoes 5.1 What are the main types of volcanoes and what are the main characteristics of eruptions
for these types? 5.2 What is a lahar? Why are lahars so dangerous 5.3 Briefly describe the impacts of a VEI 7 eruption that took place during the Holocene. You
can select one of the following eruptions: at Crater Lake (7696+-50 BP), Santorini (3629+-14 BP), or Mount Tamboro (1815).
5.4 Describe the process that caused the disaster of August 21, 1986 near Lake Nyos, Cameroon.
Group 1: Q5.1 Group 2: Q5.2 Group 3: Q5.3 Group 4: Q5.4
20 minutes
Q-Set 5: Volcanoes
