OCR A-Level Geography H481
Coastal Landscapes
Glaciated Landscapes
Dryland Landscapes
Earth’s Life Support Systems
Changing Spaces; Making Places
Trade in the Contemporary World
Global Migration
Human Rights
Power and Borders
Climate Change
Disease Dilemmas
Exploring Oceans
Future of Food
Hazardous Earth
Geographical Skills
Hazardous Earth
Effusive eruptions, shield volcanoes and hot-spot volcanism
- 2 things to know
- Component 03
Overview
Recall questions on effusive eruptions and fluid basaltic lava, shield volcanoes and Mauna Loa, fissure eruptions and Laki in 1783, lava plateaus and basalt columns, pahoehoe and aa lava, cinder cones, mantle plumes and the Hawaiian chain with a worked age calculation, Yellowstone, and the volcanoes of the East African Rift.
What you need to know
Answer each one before you reveal it.
Describe the shape of a shield volcano.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is an effusive eruption?
Model answer
An eruption in which low-viscosity lava flows steadily out of a vent or fissure rather than being blasted into the air.
- 2
Why is basaltic lava able to travel many kilometres from its vent?
Model answer
It is hot and low in silica and therefore very fluid, so it cools slowly and keeps moving, sometimes insulated inside lava tubes.
- 3
Describe the shape of a shield volcano.
Model answer
A very broad, gently domed cone with slopes of only a few degrees, far wider across than it is high.
- 4
Name the world's largest active shield volcano and state where it is.
Model answer
Mauna Loa, on the island of Hawaii.
- 5
What is a fissure eruption?
Model answer
An eruption in which lava wells up along a long crack in the crust rather than from a single central vent.
- 6
What was significant about the Laki fissure eruption of 1783?
Model answer
Lava poured from a fissure about 27 km long for eight months, and the sulphurous haze it released ruined crops and livestock, causing a famine that killed roughly a fifth of Iceland's population.
Other ways to work this
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