14.2 Hazards produced by volcanic activity Flashcards
What hazards are associated with volcanoes? X7
- Lava flows
- Pyroclastic flows
- Tephra
- Gases
- Lahars
- Floods
- Tsunamis
Describe lava flows:
Everything in lavas path is destroyed
- Basic lava is free flowing so can extend considerable distances eg 2015 Hawaii lava flowed extended 20km
- Acidic lava is thick/pasty so can not flow easily
Describe pyroclastic flows:
Combination of very hot gases, ash and rock fragments travelling at high speed (100km/h)
Destroy everything in its path and causes instant death
Eg AD79 Mount Vesuvius eruption on Pompeii
Describe tephra:
Any material ejected from a volcano into the air eg ash, lava bombs, pumice
Can bury farmland, disrupt transport, cause building collapse and respiratory problems
Eg Eyjafjallajökull 2010 eruption led to 100,000 flight cancellations
Describe toxic gases:
Include carbon monoxide, carbon dioxide, sulphur oxide
When SO2 combines with atmospheric water = acid rain which damages crops and pollutes
Describe lahars:
Mud flow with the consistency of wet concrete
Form when snow and ice on summit combine with rock and ash
Travel up to 50km/hour
Eg 1984 Nevado del Ruiz eruption in Colombia overwhelmed Armero leading to 23,000 deaths
Describe floods:
Occur when volcanic eruption happens beneath an ice field/glacier = rapid melting
Glacial outburst = jokulhlaup
Describe tsunamis:
Violent eruptions of island volcanoes cause massive displacement of ocean water
Can travel up to 600km/hour
Increase rapidly in height as they approach shore
Eg 1883 Krakatoa eruption drowned 36,000 people
What are some long-term hazards associated with volcanic eruptions?
Emission of ash into atmosphere can affect the climate as the sun is blocked and sulphuric acid reflects insolation
Eg Toba, Indonesia 70,000 years ago led to reduction in global temperatures
