Contrasting Earthquakes

Two earthquakes, and the trap

At 11:56 on the morning of 25 April 2015, a magnitude 7.8 earthquake broke the ground beneath Barpak, a village in the Gorkha district of Nepal about 80 km northwest of Kathmandu. The focus was only 8 km down, so almost all of that energy reached the surface. Around 8,900 people died, around 22,000 were injured, and roughly 8 million people, close to a quarter of the population, were affected in some way. At 12:51 on 22 February 2011, a magnitude 6.3 earthquake struck 10 km southeast of the centre of Christchurch, New Zealand, at a depth of about 5 km. It was an aftershock of a larger magnitude 7.1 quake that had hit the same region in September 2010 and killed nobody. This one killed 185 people. Here is the trap. A student sees 7.8 against 6.3, notes that a difference of 1.5 on the magnitude scale is about 180 times more energy, and concludes that Nepal suffered more because the earthquake was bigger. That answer scores badly, because the exam question is not about magnitude. Christchurch recorded vertical ground accelerations of up to 2.2 g, among the highest ever measured anywhere, and struck directly beneath a city centre on a working Tuesday lunchtime. The shaking there was, at the surface, ferocious. What separates 185 deaths from 8,900 is not mainly the number on the scale: it is what the buildings were made of, how fast help arrived, and who was going to pay to rebuild. That is what this module compares.

Five hazard terms, each with a real number

A definition on its own earns nothing in a 9-mark answer. Each of these carries the moment from 2011 or 2015 that proves it, so you can use the term and the evidence in the same sentence.

Put the six moments in order

These six events span both earthquakes. Drag them into the order they actually happened, earliest first.

• A magnitude 7.1 quake hits the Canterbury region of New Zealand before dawn and nobody is killed
• A shallower aftershock strikes under Christchurch at lunchtime and 185 people die
• New Zealand creates a national recovery authority to run the rebuild
• The ground breaks beneath Barpak in the Gorkha district of Nepal
• A magnitude 7.3 aftershock kills around 200 more people in Nepal
• Nepal finally gets its reconstruction authority up and running

Explain the gap in the death tolls

Around 8,900 people died in Nepal and 185 in Christchurch. Which answer explains that gap in the way a 9-mark question wants it explained?

• Nepal's quake released roughly 180 times more energy and shook a far larger area, but the decisive differences were what the shaking hit: homes of unreinforced brick and stone with heavy roofs, built under a code that existed on paper from 1994 but was rarely enforced because nobody could pay for inspection, against a New Zealand building stock designed for earthquakes since the 1970s; a rescue effort that had to cross landslide-blocked mountain roads and squeeze through a single-runway airport, against teams operating in a flat city within 24 hours; and a country where under 1 per cent of losses were insured, against one where insurance covered around 80 per cent.
• Nepal's earthquake was magnitude 7.8 and Christchurch's was only 6.3, so many more people were bound to die.
• Nepal has a much larger population than New Zealand.
• New Zealand predicted its earthquake and evacuated the city in advance.

The data card: eight facts each

A 9-mark named-example answer needs six to eight specific, quantified details per place. Here they are. Read the columns across, one row against its opposite number, because that pairing is exactly how the comparison should be written.

Sort four real moments

How to structure the 9-mark answer

The question will look like this: Use named examples to show how the effects of, and responses to, a tectonic hazard vary between two areas of contrasting levels of wealth. [9 marks] The single most common way to lose marks here is to write two mini-essays, one on each country, and leave the examiner to do the comparing. Instead, build the answer out of paired points. Each paragraph takes one thing, states what happened in each place with a figure attached, and then gives the wealth reason that links them. Three or four pairs is plenty. A pair looks like this in skeleton: what happened in the poorer place, what happened in the richer place, then the "because" that connects the difference to money. Good pairings to use are housing quality against death toll, the speed at which rescuers physically arrived, and who paid for the rebuilding. Deal with magnitude in a single clause early on, honestly, and then leave it: it is context, not your argument. Finish with a judgement, because "vary" invites one. The strongest closing observation on this pair is that wealth changed who died far more than it changed how much was lost: Nepal lost close to a third of a year of national income and New Zealand close to a fifth, so both countries were badly hurt in economic terms. Wealth bought survival, not immunity.

Complete the tectonic comparison

The Nepal earthquake measured _____ on the magnitude scale, against 6.3 at Christchurch, yet the shaking felt at the surface in Christchurch was among the most violent ever recorded. Around _____ people died in Nepal and 185 in New Zealand. Most Nepali homes were built of unreinforced brick and stone, so they failed as _____ effects of the shaking, while liquefaction in the eastern suburbs of Christchurch was a secondary one. New Zealand had rescue teams from overseas working within _____ hours; in parts of Nepal, helicopters were the only way in for more than a week. And when the rebuilding was costed, insurance met around 80 per cent of the New Zealand bill but under _____ per cent of the Nepali one.

Spot the three sound comparisons

Select the THREE statements that a 9-mark answer could use as they stand.

• Housing quality explains much of the difference: New Zealand had required earthquake-resistant design since the 1970s, whereas Nepal's 1994 code was seldom enforced because there was no money for inspectors, so the same shaking flattened around 500,000 Nepali homes.
• Access shaped the immediate response: foreign rescue teams were working in flat, road-served Christchurch within a day, while Nepali mountain districts were still being reached by helicopter more than a week later because landslides had closed the roads and Kathmandu had one runway.
• Who pays decides how fast a country recovers: around 80 per cent of New Zealand's roughly 40 billion dollar bill was insured, while under 1 per cent of Nepal's losses were, leaving Nepal dependent on a UN appeal that was only partly funded.
• Nepal suffered more simply because a magnitude 7.8 earthquake is much stronger than a magnitude 6.3 one.
• People in Nepal were less careful about earthquakes than people in New Zealand.
• New Zealand is rich, so the earthquake did not really harm its economy.

A paired-point answer, marked

Use named examples to show how the effects of, and responses to, a tectonic hazard vary between two areas of contrasting levels of wealth. [9 marks] The Gorkha earthquake that struck Nepal on 25 April 2015 was magnitude 7.8, considerably more powerful than the magnitude 6.3 that hit Christchurch, New Zealand, on 22 February 2011, though the New Zealand quake was unusually shallow and produced some of the fiercest surface shaking ever recorded. The gap in outcomes is therefore mostly a gap in wealth. Taking primary effects first, around 8,900 people were killed in Nepal and 185 in New Zealand. Nepali housing was largely unreinforced brick and stone under heavy roofs, and although a building code existed from 1994 there was no money to enforce it, so roughly 500,000 homes collapsed. New Zealand had built to an earthquake-resistant code since the 1970s, and although around 10,000 homes eventually needed demolishing, most stood long enough for people to get out. Turning to the immediate response, New Zealand declared a national emergency within hours and had international search and rescue teams working inside 24 hours, because the city is flat, road-served and reachable by a wealthy state. In Nepal, landslides closed mountain roads and Kathmandu airport had a single runway with weight limits that turned heavy aircraft away, so some districts waited more than a week for a helicopter. The long-term responses diverged for the same reason: around 80 per cent of New Zealand's 40 billion dollar bill was insured and a recovery authority was running within five weeks, while under 1 per cent of Nepal's losses were insured, a UN appeal for 415 million dollars was only partly met, and the reconstruction authority took eight months to function. Overall, wealth altered survival far more than it altered scale of loss: Nepal lost close to a third of a year of national income and New Zealand close to a fifth. What earned the marks: magnitude dealt with honestly in one sentence and then dropped; three paired points, each naming both places with figures and giving the wealth reason that links them; and a final judgement that answers "vary" rather than just stopping. Note that no paragraph is about only one country.

Find the sentences that do the real work

Below are five sentences taken from a student's draft. Two of them actually link a difference between the two places to wealth, which is what the question rewards. Tap those TWO.

• Nepal had a building code from 1994 but could not afford to enforce it, while New Zealand had funded inspection of earthquake-resistant design for decades, which is why collapse killed thousands in one country and hundreds in the other.
• Both earthquakes happened during the daytime.
• Because New Zealand households were insured and Nepali ones were not, one country could start rebuilding on its own money within weeks while the other was still waiting on an international appeal months later.
• Nepal lies where the Indian plate is pushing into the Eurasian plate.
• The earthquake in Nepal was a terrible tragedy for the people who lived there.

Build a comparison that does not overclaim

Choose the wording that stays accurate about the role magnitude played.

Four decisions from the two disasters

Each stage below is a real decision point. Pick what was actually done, and notice how the money available shaped what was even possible.

• Late April 2015. Aid flights are stacking up over Kathmandu. The airport has one runway and a surface that will not take the heaviest transport aircraft fully loaded. Mountain districts have had nothing for four days.
• 22 February 2011, early afternoon. Central Christchurch is full of collapsed and unstable buildings, and hundreds of people are trapped. You are the New Zealand government.
• 2011 to 2012. Liquefaction has left thousands of Christchurch homes standing on ground that will do the same again in the next quake. Repairing them where they are would be pointless.
• June 2015. The monsoon is arriving. Hundreds of thousands of Nepali families are under tarpaulins, the UN appeal is only partly funded, and the reconstruction authority is still not operating.

Write the 9-mark comparison

Use named examples to show how the effects of, and responses to, a tectonic hazard vary between two areas of contrasting levels of wealth. [9 marks]

• Name both earthquakes with their dates and magnitudes in your first sentence, and settle the magnitude point there so it does not run through the whole answer
• Write in paired points: take one thing at a time, give what happened in Nepal and what happened in Christchurch with a figure for each
• Attach a wealth reason to every pair, using words such as "because" or "which meant that", so the difference is explained and not just described
• Cover at least one effect pair and one response pair, for example housing against death toll, and how quickly rescuers physically arrived
• End with a judgement on how far wealth explains the difference, remembering that both countries lost a large share of a year of national income