Benefits of volcanic activity

Overview

Why volcanic soils are fertile and which farming systems gain, the energy and minerals volcanic activity yields, the tourism it supports, and the new land it creates.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Why are volcanic soils so fertile?

   Model answer

   Volcanic ash and lava are rich in minerals such as potassium, phosphorus, magnesium and calcium, and ash in particular is made of tiny fragments with a very large surface area, so it weathers quickly and releases those nutrients into the soil. The resulting soils are also often deep, well drained and good at holding water. A fresh ash fall effectively fertilises the land, which is why farming on volcanic slopes gives high yields and supports dense populations.

2. 2

   Which crops and farming systems benefit most from volcanic soils?

   Model answer

   High-value crops grown on the fertile, well-drained slopes: coffee, tea, cocoa, vines, tobacco, bananas and market vegetables, alongside intensively terraced rice on the lower slopes in monsoon Asia. The combination of fertile soil, reliable relief rainfall and, at altitude, cooler temperatures suits crops that could not be grown on the surrounding lowlands, so volcanic districts often produce a disproportionate share of a country's agricultural exports.

3. 3

   How does volcanic activity provide energy?

   Model answer

   Through geothermal power. Groundwater circulating through hot rock above a shallow magma body is heated to high temperatures, and where it can be reached by drilling it rises as steam and superheated water. The steam is used directly to drive turbines and generate electricity, and the hot water is piped to heat homes, greenhouses, swimming pools and industry. It is a renewable, low-carbon and continuously available supply, unaffected by weather, and in a volcanically active country such as Iceland it supplies the great majority of space heating and a substantial share of electricity.

4. 4

   What mineral resources are associated with volcanic activity?

   Model answer

   Hot fluids circulating through volcanic rock concentrate metals into ore bodies, so volcanic and former volcanic regions supply copper, gold, silver, tin, lead and zinc, with the great copper deposits of destructive margins a leading example. Sulphur is mined directly from craters and fumaroles. Diamonds reach the surface in ancient volcanic pipes. Volcanic rock itself is quarried as building stone and aggregate, and pumice and ash are used in cement, in abrasives and as lightweight construction material.

5. 5

   How does volcanic activity support tourism, and what are the drawbacks of relying on it?

   Model answer

   Volcanic landscapes attract visitors through dramatic scenery, craters and lava fields, hot springs, geysers, mud pools and spas, the chance to see an active eruption, and volcanic beaches, bringing income, jobs in guiding, transport, accommodation and catering, and foreign currency. The drawbacks are that the income is seasonal and can be wiped out overnight by an eruption or by exclusion zones, that it may employ people in low-paid or insecure work, that visitors put pressure on fragile landscapes, and that it can place large numbers of unfamiliar people close to a dangerous volcano.

6. 6

   How does volcanic activity create new land?

   Model answer

   Erupted lava solidifies into new rock, extending coastlines where flows reach the sea and, in extreme cases, building entirely new islands from the sea floor, as Surtsey was built off Iceland. Over geological time this is how whole island chains such as Hawaii and Iceland itself have come into existence. The new land is initially barren but is colonised remarkably quickly by plants and animals, providing scientists with rare opportunities to study ecological succession from bare rock.

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