Volcanic eruptions generate distinctive hazards Flashcards
1
Q
What are the different types of volcanic eruptions?
A
- Icelandic
- Hawaiian
- Strombolian
- Vulcanian
- Vesuvius and Plinian
2
Q
What are the characteristics of Icelandic eruptions?
A
- persistent fissures
- low viscosity lava (basaltic)
- low gas content
3
Q
What are the characteristics of Hawaiian eruptions?
A
- effusion of low viscosity lava (basaltic)
- outflows from fissures & the summit
- lava fountains appear
- has low gas content
- and little volcanic ash
4
Q
What are the characteristics of Strombolian eruptions?
A
- explodes fragments of low viscosity (basaltic) lava into the air
- small/frequent gas explosions
- white steam is emitted from the crater
5
Q
What are the characteristics of Vulcanian eruptions?
A
- explosive blasts of plugs of sticky high viscosity lava (Andesitic/Ryholitic) clearing a blocked vent
- violent gas explosions
- high amounts of volcanic ash
6
Q
What are the characteristics of Vesuvian eruptions?
A
- explosion of fragments of high viscous lava (Andesitic/Rhyolitic) jetted upwards
- pressure building over long periods
- results in violent bursts of gas
- ash cloud up to 45km high
- generates lightning strikes
- and massive pyroclastic flows
7
Q
What are pyroclastic flows?
A
- fast-moving current of hot gas (500°C)
- consisting of volcanic matter (tephra) up to 50mph.
8
Q
What impacts do pyroclastic flows cause?
A
- destroys the majority of things in its path
- causes fires
- floods
- buries objects and structures or may carry them away
- deaths and serious injuries
9
Q
What are lahars?
A
- fast moving volcanic mud flows
- capable of travelling long distances
- has consistency of wet concrete
- composed of ash deposits and rock fragments mixed with water
10
Q
What are the impacts of lahars?
A
- destroys most things in its path under layers of debris
- damages river valleys
- floodplains and entire villages
11
Q
What causes a tsunami?
A
- violent volcanic eruptions occurring at ocean islands or an under sea volcano
- causes a significant displacement of water
- which generates waves
12
Q
How big are tsunamis in general?
A
- in deep water has a height of 1m
- wavelength of 200km
- wave height can increase up to 40m on approach to shore
13
Q
What is tephra?
A
- rock fragments and particles ejected into the air
- ranging from fine ash to volcanic bombs
14
Q
What are the impacts of ash clouds?
A
- cover land and sea surface
- contaminate water
- damage power supplies
- closure of airspace
- crop damage
- collapse buildings
- respiratory problems from inhalation of volcanic ash
15
Q
What are the impacts of gas emissions?
A
- CO makes eruption more explosive
- CO2 is denser than air and displaces breathable air
- SO2 mixes with water in the atmosphere and creates acid rain
- this pollutes surface water
- enhances weathering
- damages crops,
- and irritates eyes, skin and respiratory system
