Risk and Response

Why anyone lives there at all

Vesuvius has erupted more than fifty times since it buried Pompeii in AD 79, and the Italian authorities have drawn a red zone around it from which everyone would have to be evacuated. Around 600,000 people live inside that line, and about 3 million live close enough to be affected. Italy has offered cash grants to households willing to move away. Very few take them. That is not stupidity, and an answer which says people "do not realise the danger" will not score. People stay for reasons that are entirely rational in the short term. Volcanic ash and lava weather into some of the most fertile soil on Earth, which is why roughly 140 million people farm the volcanic island of Java, and why there are vineyards on the flanks of Etna. Volcanic heat is free energy: around 90 per cent of Icelandic buildings are heated geothermally. There are minerals to mine, tourists to serve, and, above all, there is the ordinary gravity of a life already built, with a job, a family, a house that is worth nothing if nobody will buy it. A large eruption may come once in several generations. Next month's rent comes every month. So the geographer's question is not why people stay but what can be done for them, and there are exactly four answers: monitoring, prediction, protection and planning. They are four different activities, they cost wildly different amounts, and the commonest way to lose marks on this topic is to treat them as interchangeable. This module keeps them apart.

Four responses and one idea, kept apart

Read these as a set of contrasts rather than five separate definitions. The differences between them are where the marks are.

Order the Pinatubo warning

These six stages took place at Mount Pinatubo in the Philippines between April and June 1991. Put them in the order they happened.

• A mountain quiet for centuries begins venting steam and small explosions
• Seismometers are installed and record thousands of small tremors as magma rises
• Measured sulphur dioxide output climbs sharply, then drops as the vent seals
• Scientists raise the alert level and persuade the authorities to act
• Around 60,000 people are moved out of the danger zone in the days before the climax
• The mountain erupts massively, and the death toll is a fraction of what it would have been

Why do people stay in the danger zone?

Which answer best explains why hundreds of thousands of people continue to live on the slopes of an active volcano?

• The benefits are immediate and the danger is not. Weathered ash and lava make exceptionally fertile soil, which is why Java supports around 140 million people; volcanic heat is cheap energy, heating about 90 per cent of Icelandic buildings; there are minerals, tourists and jobs. Set against that, a major eruption may come only once in several generations, many residents have never seen one, and leaving means abandoning work, family and a house nobody would buy. For the poorest there is no realistic alternative at all.
• They do not realise that the volcano is dangerous.
• Modern engineering has made volcanic eruptions completely safe to live beside.
• Governments force people to live there.

What is actually possible, hazard by hazard

This is the single most important contrast in the topic, and it is the one students get wrong. One of these hazards can be predicted and the other cannot, so the four responses do not carry equal weight for both.

Match each measure to what it really is

Keeping the four apart, and the 9-mark structure

Examiner reports on this topic say the same thing every year: candidates use monitoring, prediction, protection and planning as though they were synonyms. A quick test for each sentence you write. Does it involve an instrument reading the hazard? That is monitoring. Does it involve a statement about when? Prediction. Does it involve concrete, steel or rubber? Protection. Does it involve telling people what to do? Planning. Be precise about earthquakes. Writing that "earthquakes can be predicted using seismometers" is wrong and will cost you. Seismometers record quakes that are already happening. The Japanese system that gives Tokyo about a minute of notice is detecting a quake that has already begun and racing the message ahead of the slower, damaging waves, which is early warning, not prediction. For a 9-mark question such as "Assess the extent to which planning is more effective than protection in reducing the effects of tectonic hazards. Use named examples.", the shape is: make the case for one with a named example and a figure, make the case for the other the same way, then judge on a criterion you state. The strongest criterion here is cost per life saved, because it splits the answer along the wealth line. Protection is the most reliable defence and also the most expensive, so it is available where money is; planning costs comparatively little and is therefore the response that most of the world can actually afford. Say that, and you have a judgement rather than a summary.

Complete the hazard response facts

Before Mount St Helens erupted in 1980, instruments recorded the north flank bulging outwards at about _____ m a day, which is an example of monitoring rather than prediction. At Mount Pinatubo in 1991 the monitoring data were good enough to evacuate around _____ people before the eruption. No equivalent warning is possible for an earthquake, because there is no reliable signal of one building; what Japan operates instead is _____ warning, which gave Tokyo roughly 60 seconds in 2011 after the shaking had already started. Engineering that keeps a building standing, such as the _____-tonne pendulum inside Taipei 101, is protection. Rehearsing an evacuation on the national drill day every 1 September is _____, and it is the cheapest of the four responses by a wide margin.

Spot the three accurate risk statements

Select the THREE statements that are true.

• Japan's building protection worked in 2011 even though the disaster was enormous: the magnitude 9.0 shaking brought down very few buildings, and almost all of the roughly 18,500 deaths were caused by the tsunami that followed, which the sea walls were too low to stop.
• Planning is the response most available to poorer countries, because hazard maps, marked routes, drills and education cost a small fraction of what retrofitting a city's buildings would cost.
• Volcanoes can usually be predicted with days or weeks of warning because rising magma produces tremors, ground swelling and changes in gas emissions that instruments can track.
• Earthquakes can now be predicted several days in advance using seismometers.
• Nothing can be done to reduce earthquake deaths, so the only sensible response is to move away.
• People live in hazard zones mainly because they are unaware of the risk.

A 9-mark assessment, marked

Assess the extent to which planning is more effective than protection in reducing the effects of tectonic hazards. Use named examples. [9 marks] Protection has the strongest single piece of evidence in its favour. Japan enforces one of the most demanding building codes in the world, using cross-bracing, deep foundations and base isolation, and in March 2011 a magnitude 9.0 earthquake, among the most powerful ever recorded, brought down remarkably few buildings; of the roughly 18,500 people who died, almost all were killed by the tsunami rather than by the shaking itself. That is protection working exactly as intended. However, the same disaster shows its limit, because the sea walls that were meant to protect the coast were overtopped, and building to that standard is only possible for a country that can pay for it. Planning is far cheaper and reaches everybody. Japan also runs a national drill every 1 September in which millions rehearse, and its early warning system gave Tokyo roughly 60 seconds in 2011, enough for bullet trains to brake automatically and for gas supplies to cut off. The clearest case for planning is Mount Pinatubo in 1991, where monitoring was turned into a decision to evacuate around 60,000 people, so that one of the century's largest eruptions killed around 850 rather than tens of thousands: no engineering could have achieved that, and it cost almost nothing by comparison. Judged on cost per life saved, planning is therefore the more effective response, and decisively so for the low-income countries where most tectonic deaths occur. Judged on protecting property and economic activity, protection wins, because a drill saves a person and a building code saves a city. The honest assessment is that they answer different questions, and that a poor country which can afford only one should choose planning. What earned the marks: both sides argued with named examples and figures rather than asserted; the limits of the strongest case acknowledged; a stated criterion, cost per life saved, doing the actual judging; and a conclusion that answers "to what extent" instead of declaring a winner and stopping.

Find the two that are protection

Five measures taken in tectonically active places. Two of them are protection, meaning engineering that keeps a structure standing or a flow away. Tap those TWO.

• A hospital is rebuilt on bearings of rubber and lead so that the ground can move beneath it without the walls following.
• A hazard map is drawn showing which valleys would be swept by mudflows, and new housing is refused there.
• Concrete dams are built across steep valleys to catch the ash-laden mudflows before they reach the towns below.
• Households are advised to keep three days of water, a torch and a radio in a bag by the door.
• Schools rehearse getting under desks and then walking to high ground.

Write the prediction sentence correctly

Assemble a sentence that states the position on earthquake warning accurately.

Four decisions, four budgets

Each stage is a real choice faced by people managing tectonic risk. Pick the response that was actually chosen, and notice which of the four it is.

• June 1991, the Philippines. Your instruments show thousands of tremors and a sharp fall in gas output, which suggests the vent has sealed and pressure is rising. Evacuating will cost a fortune and wreck your credibility if nothing happens.
• January 1973, Iceland. A fissure has opened beside your fishing town and a lava flow is advancing on the harbour entrance. Lose the harbour and the town has no reason to exist.
• You advise a government with a large budget, a dense population and frequent quakes. You can spend on one thing above all others.
• You advise a low-income government on an active margin. Retrofitting the building stock would cost many times your annual budget, and most housing is built informally by the families who live in it.

Explain how risk can be reduced

Explain how monitoring, prediction, protection and planning can reduce the risks from tectonic hazards. Use named examples. [9 marks]

• Take the four responses in turn and define each by what it actually involves, so they are visibly different things
• Attach a named example and a figure to each one, for instance the bulge measured at Mount St Helens or the evacuation at Pinatubo
• Be accurate about earthquakes: say plainly that they cannot be predicted, and describe early warning as detection of a quake already under way
• Use a link phrase such as "this means that" so each response is explained as reducing risk, not merely described
• Close by saying which responses a poorer country can realistically use, and why that makes planning so important