Chapter 1 Gateway 2 Landforms Flashcards
Compare the shapes of stratovolcanoes and shield volcanoes
Stratovolcanoes have steep sloping sides with a narrow summit, while shield volcanoes have gentler sloping sides with a broader summit
Describe the formation of a volcano
At convergent or divergent plate boundaries, magma rises, and accumulates in the magma chamber, where pressure builds up until the magma forces its way onto the Earth’s surface through vents.
The ejected lava builds around the vent to form a volcano
How does silica content in lava affect the shape of the volcano?
With low-silica lava, the viscosity is low, so the eruptions are not explosive as the lava does not trap much gas, causing the lava to flow over a large area before solidifying.
This leads to the volcano having gently sloping sides with a broad summit
Conversely, lava with high viscosity flows over a shorter distance before it cools and solidifies, resulting in a thicker crust over successive eruptions.
This leads to a tall volcano with a narrow summit
What is pyroclastic flow?
It refers to ash, rock fragments, gases ejected from a volcano, typically flowing at a high speed
What are the benefits of living near volcanoes?
Fertile soil
Precious stones and minerals
Tourism
Geothermal energy
What are the risks of living near volcanoes?
Massive destruction by volcanic materials
Pollution
What is one social impact of risks when living near volcanoes?
P: Civilian casualties from massive destruction by volcanic materials
Elab: Landslides can occur due to the structural collapse of a volcanic core during an eruption → obstruct flows of rivers, roads, bury villages or farmland
Eg: Eruption of Nevado del Ruiz in Andes mountains in 1985 released a pyroclastic flow which mixed with the glacial ice to trigger lahars, engulfing the town of Armeno and killing more than 20000 people
L: Living near volcanoes can lead to extensive casualties and even major deaths of residents
What is one economic impact of risks when living near volcanoes?
P: Economic decline due to ash pollution
Elab: Ash particles ejected during a volcanic eruption can disrupt human activities over large distances from the volcano. The abrasive debris in ash clouds pose a serious threat to aircrafts → debris enters the engine and causes it to stall, potentially crashing the plane
Eg: The eruption of Eyjafjallajokull in Iceland in 2010 produced extensive volcanic ash clouds containing tiny particles of abrasive glass, sand and rock. The eruption resulted in a closure of air space over much of Europe. Connecting flights worldwide were cancelled, costing the airline industry a total of US1.8 billion
L: Ash threat to planes → close air space → business $ decline
Give an example of an economic and social impact from massive destruction by volcanic materials
Eruption of Kilauea in Hawaii since 1983 has destroyed many homes and highways
Social: Loss of peoples’ homes → nowhere to reside in → increased mental stress
Economic: Large funds required to restore damaged infrastructure → lose $ and damage economy
What is a benefit of living near volcanoes?
(Presence of precious stones and minerals)
P: Economic growth from presence of precious stones and minerals.
Elab: Volcanic rocks can be rich in precious stones and minerals. These resources can only be extracted from volcanic areas after millions of years. A precious stone from volcanic rocks is diamond. Diamonds are heated and pressurised carbon that are cooled in magma pipes beneath the Earth’s surface. When refined, diamonds are useful as industrial tools and in scientific research, as well as making jewellery
Eg: The old volcanic rocks at Kimberly in South Africa are one of the world’s richest source of diamonds
L: Presence of precious stones and minerals → source of income
What is a benefit of living near volcanoes?
(Fertile soil)
P: Economic growth from presence of fertile soil
Elab: Lava and ash from volcanic eruptions break down to form fertile volcanic soils. As the richest soils on the earth, volcanic soils are very favourable to agriculture
Eg: The volcanic soils of Java and Bali in Indonesia support the cultivation of crops such as tea, coffee and rice. Despite continuous use, the soils are more fertile than most non-volcanic areas of Indonesia
L: Boom in the agricultural industry → $ growth
What is a benefit of living near volcanoes?
(Tourism)
P: Economic growth due to tourism
Elab: Many people visit volcanoes to hike and camp in the area or simply to enjoy the scenery. Volcanic areas are rich in history and people can visit these areas to learn more about them.
Eg: Pompeii, Italy, was buried by layers of ash from the nearby Mount Vesuvius when it erupted in 79 CE; 3 million people visit the site every year
L: Boom in the tourism industry → $ growth
What is a benefit of living near volcanoes?
(Geothermal energy)
P: Economic growth from presence of geothermal energy
Elab: Geothermal energy is derived from heat in the earth’s crust. When groundwater comes into contact with hot rocks beneath the surface, it heats up and erupts as hot water or steam. The hot water or steam can be harnessed to drive turbines and produce electricity.
Eg: Over 70% of Iceland’s electricity is generated from geothermal power because of the large number of volcanoes in the country
L: Presence of geothermal energy → natural source of energy → save $ on electricity → economic growth
