5.3.2 Flashcards
Explain why tephra is a hazard
Tephra – solid material of varying sizes that is ejected by a volcano – ranges from ash (less than 2mm in diameter) to volcanic bombs (more than 64mm)
Explain why ash fallout is a volcanic hazard
Ash fallout – large quantities of ash carried by the wind and deposited on the ground
It can travel many km, causing respiratory problems, injuries, damage, deaths and disruption to transport
E.g. the 2010 Eyjafjallajökull eruption in Iceland produced an ash cloud that disrupted air travel in Europe for several weeks
Explain why pyroclastic flow is a volcanic hazard
Pyroclastic flow (also known as nuée ardente) - a super-heated mixture of gas and tephra that flows at speeds of up to 700 km per hour
This is one of the deadliest volcanic hazards as they can travel long distances and destroy everything in their path
E.g. when Fuego volcano erupted in Guatemala in 2018, pyroclastic flows destroyed several nearby towns
Explain why lava flow is a volcanic hazard
Lava flow – lava flows travel at different speeds depending on slope, temperature and viscosity
Most move slowly enough that they are not a risk to human life but can cause significant damage to property and infrastructure
The fastest flows can reach speeds of up to 60 mph
In the 2021 eruption of Mount Nyiragongo in the Democratic Republic of Congo, lava flows travelled almost 10km destroying properties and killing over 30 people
Explain why volcanic gases are a volcanic hazard
Volcanic gases – eruptions can release large quantities of gases such as sulphur dioxide and carbon dioxide
They are hazardous to human health causing respiratory problems and deaths
E.g. Kilauea in Hawaii (USA) releases large amounts of sulphur dioxide leading to air quality alerts and health warnings for residents
Outline 3 secondary volcanic hazards
Lahars
Jokulhlaups
Acid rain
Explain why lahars are a volcanic hazard
Lahars – mudflows that occur when tephra mixes with water, either from rainfall, or from melted snow and ice
They are fast flowing and destroy everything in their path
E.g. the lahars that occurred when Mount Pinatubo erupted in the Philippines in 1991 caused extensive damage and disruption
Explain why Jokulhlaups are a secondary hazard
Jökulhlaups - floods caused by a sudden release of water and rocks when glacial ice is melted by the eruption
The 2010 eruption of Eyjafjallajökull triggered a jökulhlaup which destroyed several bridges and roads
Explain why acid rain is a volcanic hazard
Acid rain – forms when sulphur dioxide emitted during the eruption reacts with water vapour in the atmosphere to form sulphuric acid
It can damage crops, forests and aquatic ecosystems
