Types of Volcano
Shield: gentle sloping, created by basic lava (travels along way before solidifying). Found at constructive boundaries.
Composite: alternating layers of acid lava & rock/ash create the classic conical shape. Found at destructive boundaries.
Ash & cinder: Alternating layers of ash & cinder compacted.
Fissure: volcanoes running along a crack in the crust, usually a constructive boundary.
Caldera: Crater volcano created after volcano collapses in on itself having emptied the magma chamber.
Dome: steep sided volcano created by acid lava which cools before it has travelled far.
Destructive boundary volcanoes are often cone shaped and explosive.
Constructive boundary volcanoes are often more gently sloped and have less violent erruptions.
Objective: be able to correctly label the key features of volcanoes and relate them to the increased risk they pose to human settlements.
Volcanoes vary in shape and structure depending on the reason for their existence.
Secodary vents (fumaroles) occur when magma and gases force their way through weaknesses in the main volcanic structure.
Lava, ash, cinders and smoke may be ejected from the vent.
Draw and label a simple diagram of a volcano and the ejected material.
Make simple sketch diagrams showing fissure, dome and ash-cinder volcanic structures.
Using Figure 2.0, describe the location of the Pacific Ring of Fire and explain why this area has this name.
Figure 2.1.2: Volcano Features
Costs & Benefits of Volcanic Environments
Volcanic eruptions can cause significant damage and loss of life.
Lava flows destroy vegetation buildings and roads.
Ash can smother plants, cut out light in the atmosphere, disrupt air travel and cause respiration problems for people.
Eruptions often cause earthquakes as pressure is released.
Volcanoes with ice near the peak, or crater lakes can cause devastating mud flows as the water mixes with loose ash.
Gas released from volcanoes can travel down the slopes silently killing people and animals.
Volcanoes can bring environmental and socio-economic benefits.
Fertile soils: ash and lava contain many minerals and nutrients that weather to form fertile soils which can be used very effectively for farming.
Sulphur deposits: sulphur is mined and sold by the people living close to volcanoes in Indonesia.
Tourism: the volcanic scenery, crater lakes, hot spring and geysers attract tourists and create many job opportunities.
Objective: be able to describe the main events and damage caused by the volcano. You should be able to suggest reasons for the extent of the damage.
Montserrat is an island in the Caribbean that unexpectedly suffered devastating eruptions.
Tasks Using the google map shown to the right, describe the location of Montserrat on a regional scale.
Draw a sketch map showing the location of the Sufriere Hills volcano within the island.
Watch video 2.1.4:
Explain the cause of the volcano
Describe the main effects/impacts of the eruptions
Why did they cause so much damage on the island? Make a sketch of Figure 2.1 to show the hazard map and restricted zones that are in place on Montserrat since the eruption.
VIDEO Video 2.1.4: Montserrat eruption
Figure 2.1: Hazard Map of Montserrat after the eruption