AQA A-level Geography · 3.1.5

Seismic hazards

50 exam-style questions with answers for 3.1.5 Seismic hazards in AQA A-level Geography (spec 7037). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, or read every question and answer below. Not official AQA material.

All 50 questions and answers

Question 1 · Spec 3.1.5.4 · Nature of seismicity
Distinguish between the focus and the epicentre of an earthquake. [2 marks]
Answer:
The focus is the point underground where the rocks break and energy is released (1); the epicentre is the point on the surface directly above the focus (1).
Question 2 · Spec 3.1.5.4 · Nature of seismicity
Explain how an earthquake occurs at a plate boundary. [3 marks]
Answer:
Plates move, but friction locks them together, so strain builds up in the rocks (1); eventually the strain exceeds the strength of the rock and it fractures suddenly along a fault (1); energy is released as seismic waves that shake the ground (1).
Question 3 · Spec 3.1.5.4 · Nature of seismicity
Describe the main types of seismic wave. [3 marks]
Answer:
P waves are fast compressional waves that travel through solids and liquids (1); S waves are slower shear waves that travel only through solids (1); surface waves travel along the ground, are slowest and cause the most damage (1).
Question 4 · Spec 3.1.5.4 · Nature of seismicity
Explain why the largest earthquakes occur at subduction zones. [3 marks]
Answer:
Plates lock over a very large contact area (1); strain builds for decades or centuries (1); when it is released, a huge area of fault ruptures, producing a megathrust earthquake of very high magnitude (1).
Question 5 · Spec 3.1.5.4 · Nature of seismicity
Explain why shallow earthquakes usually cause more damage than deep ones. [2 marks]
Answer:
Seismic waves from a shallow focus reach the surface with more energy (1); waves from a deep focus lose energy as they travel upwards (1).
Question 6 · Spec 3.1.5.4 · Nature of seismicity
Explain how the epicentre of an earthquake is located. [3 marks]
Answer:
Seismometers record the arrival of P and S waves (1); the gap between their arrival times gives the distance from the earthquake (1); circles drawn from three or more stations intersect at the epicentre (1).
Question 7 · Spec 3.1.5.4 · Magnitude and frequency
Describe the moment magnitude scale and the Mercalli scale. [3 marks]
Answer:
The moment magnitude scale measures the energy released by an earthquake (1); it is a logarithmic scale, so each whole number is about 32 times more energy (1); the Mercalli scale measures the intensity of shaking and damage on a scale of I to XII (1).
Question 8 · Spec 3.1.5.4 · Magnitude and frequency
The amplitude of shaking increases tenfold for each whole number on the magnitude scale. Calculate how many times greater the amplitude is for a magnitude 7 earthquake than for a magnitude 5 earthquake. [2 marks]
Answer:
Two whole numbers apart (1); 10 × 10 = 100 times greater (1).
Question 9 · Spec 3.1.5.4 · Magnitude and frequency
Describe the global frequency of earthquakes of different magnitudes. [3 marks]
Answer:
About one earthquake of magnitude 8 or more each year (1); about 15 of magnitude 7 to 7.9 each year (1); over a hundred of magnitude 6 to 6.9, and many more small ones (1).
Question 10 · Spec 3.1.5.4 · Magnitude and frequency
Explain the randomness of earthquake events. [2 marks]
Answer:
Earthquakes do not follow a regular pattern in time, even on the same fault (1); the strain that builds up and the strength of the rock cannot be measured exactly, so timing is unpredictable (1).
Question 11 · Spec 3.1.5.4 · Prediction
Explain why earthquakes cannot be predicted. [3 marks]
Answer:
Stress builds up deep underground where it cannot be observed (1); there are no reliable warning signs before the main shock (1); foreshocks, animal behaviour and gas emissions are inconsistent, and false alarms are common (1).
Question 12 · Spec 3.1.5.4 · Prediction
Explain how earthquake early warning systems work and their limitations. [3 marks]
Answer:
Sensors detect fast P waves and send automatic alerts before slower, more damaging S waves arrive (1); alerts can stop trains, shut off gas and give people a few seconds to take cover (1); limitation: little or no warning near the epicentre (1).
Question 13 · Spec 3.1.5.4 · Prediction
Explain what is meant by an earthquake forecast. [2 marks]
Answer:
A statement of the probability that an earthquake of a certain size will occur in an area within a time period (1); it is based on past earthquakes and strain on faults, not on exact timing (1).
Question 14 · Spec 3.1.5.4 · Forms of hazard
Describe the hazards caused by ground shaking. [3 marks]
Answer:
Buildings and bridges collapse (1); roads, railways and pipelines are broken (1); falling debris and objects injure and kill people (1).
Question 15 · Spec 3.1.5.4 · Forms of hazard
Explain what is meant by liquefaction. [3 marks]
Answer:
Loose, water-saturated sediment loses its strength when shaken (1); it behaves like a liquid (1); buildings tilt or sink, and underground pipes and tanks float upwards, as in Christchurch in 2011 (1).
Question 16 · Spec 3.1.5.4 · Forms of hazard
Explain how earthquakes trigger landslides. [2 marks]
Answer:
Shaking loosens rock and soil on steep slopes (1); landslides bury roads and villages and block rivers, which can cause flooding (1).
Question 17 · Spec 3.1.5.4 · Forms of hazard
Explain how an earthquake can cause a tsunami. [4 marks]
Answer:
Plates under the sea suddenly move vertically along a fault (1); this displaces a large volume of water above (1); waves travel across the ocean at high speed with a small height (1); they slow and grow taller as they reach shallow water near the coast (1).
Question 18 · Spec 3.1.5.4 · Forms of hazard
Explain why tsunamis do more damage on some coasts than others. [2 marks]
Answer:
Funnel-shaped bays and low-lying land concentrate and extend the flooding (1); coasts without natural barriers or sea walls, or close to the source, receive waves with more energy (1).
Question 19 · Spec 3.1.5.4 · Forms of hazard
Describe how tsunami warning systems work. [3 marks]
Answer:
Seismometers detect earthquakes that may cause tsunamis (1); deep-ocean buoys detect changes in sea level (1); warnings are sent by sirens, phones and broadcasts to coastal communities so that they can evacuate (1).
Question 20 · Spec 3.1.5.4 · Forms of hazard
Explain what the 2004 Indian Ocean tsunami showed about the need for warning systems. [3 marks]
Answer:
A magnitude 9.1 earthquake off Sumatra caused waves that reached 14 countries (1); about 230,000 people died, many of them hours after the earthquake in countries such as Sri Lanka and India (1); there was no warning system in the Indian Ocean, and one was set up afterwards (1).
Question 21 · Spec 3.1.5.4 · Forms of hazard
Explain how fires can follow earthquakes. [2 marks]
Answer:
Broken gas mains and electrical cables ignite (1); damaged water pipes and blocked roads make it hard to put fires out, as after the 1995 Kobe earthquake (1).
Question 22 · Spec 3.1.5.4 · Forms of hazard
Explain why aftershocks are hazardous. [2 marks]
Answer:
They can collapse buildings already weakened by the main shock (1); they hinder rescue and make people afraid to return home (1).
Question 23 · Spec 3.1.5.4 · Impacts
Distinguish between primary and secondary impacts of an earthquake. [4 marks]
Answer:
Primary impacts are caused directly by shaking, such as collapsed buildings (1); and deaths and injuries (1); secondary impacts follow later, such as tsunamis, fires and landslides (1); and disease, homelessness and loss of income (1).
Question 24 · Spec 3.1.5.4 · Impacts
Describe the social impacts of earthquakes. [3 marks]
Answer:
Deaths, injuries and trauma (1); homelessness and displacement into temporary camps (1); disruption of schools, hospitals and communities, and the spread of disease where water and sanitation fail (1).
Question 25 · Spec 3.1.5.4 · Impacts
Describe the economic impacts of earthquakes. [3 marks]
Answer:
Costs of repairing buildings and infrastructure are very high (1); businesses close and jobs are lost, and trade and tourism fall (1); insurance costs rise, and aid and debt may be needed to rebuild (1).
Question 26 · Spec 3.1.5.4 · Impacts
Describe the environmental impacts of earthquakes. [3 marks]
Answer:
Landslides and ground ruptures change landscapes (1); tsunamis flood land with salt water and debris, damaging soil and habitats (1); damaged industry or power stations release pollution (1).
Question 27 · Spec 3.1.5.4 · Impacts
Describe the political impacts of earthquakes. [3 marks]
Answer:
Governments are criticised for poor building standards or slow response (1); money is diverted to recovery, affecting other services (1); international aid can improve relations, or tensions can arise if aid is mismanaged (1).
Question 28 · Spec 3.1.5.4 · Impacts
Explain why building collapse is the main cause of death in earthquakes. [2 marks]
Answer:
Many people are inside buildings when shaking starts (1); poorly built structures made of unreinforced brick or concrete fail suddenly and trap people (1).
Question 29 · Spec 3.1.5.4 · Impacts
Explain why the type of ground affects earthquake damage. [2 marks]
Answer:
Soft sediments amplify shaking and can liquefy (1); solid bedrock transmits less shaking, so buildings on it suffer less damage (1).
Question 30 · Spec 3.1.5.4 · Responses
Describe the short-term responses to an earthquake. [3 marks]
Answer:
Search and rescue, with the first 72 hours the most critical for survivors (1); medical treatment, emergency shelter, food, clean water and sanitation (1); restoring power, roads and communications (1).
Question 31 · Spec 3.1.5.4 · Responses
Describe the long-term responses to an earthquake. [3 marks]
Answer:
Rebuild homes, schools and infrastructure to higher standards (1); relocate people away from the most dangerous areas (1); improve building codes, training and warning systems, and restore the economy (1).
Question 32 · Spec 3.1.5.4 · Responses
Explain how preparedness reduces earthquake risk. [3 marks]
Answer:
Regular drills teach people to drop, cover and hold on, as in Japan on Disaster Prevention Day each 1 September (1); households keep emergency kits and plans (1); emergency services train and stockpile equipment (1).
Question 33 · Spec 3.1.5.4 · Responses
Describe how buildings can be designed to withstand earthquakes. [4 marks]
Answer:
Reinforced concrete and steel frames flex without collapsing (1); cross-bracing and shear walls stiffen the structure (1); base isolators absorb ground movement (1); tuned mass dampers or counterweights on tall buildings reduce swaying (1).
Question 34 · Spec 3.1.5.4 · Responses
Explain why retrofitting is important in reducing earthquake risk. [2 marks]
Answer:
Most buildings in earthquake zones are old and were built to lower standards (1); strengthening them is cheaper than replacing them and reduces collapse and death (1).
Question 35 · Spec 3.1.5.4 · Responses
Explain how land-use planning reduces earthquake risk. [2 marks]
Answer:
Zoning avoids building on soft ground, fault lines and steep slopes (1); open spaces for evacuation and assembly are included, and essential services are built to higher standards (1).
Question 36 · Spec 3.1.5.4 · Responses
Explain why earthquakes cannot be prevented. [2 marks]
Answer:
The movement of plates and the build-up of strain cannot be stopped or controlled (1); only the impacts can be reduced, by preparing, mitigating and adapting (1).
Question 37 · Spec 3.1.5.4 · Recent events
Tohoku, Japan, 2011: describe the nature of the earthquake and tsunami. [3 marks]
Answer:
A magnitude 9.0 earthquake on 11 March 2011 off the coast of Honshu, where the Pacific plate subducts beneath Japan (1); a tsunami followed, with waves up to about 40 m high in places (1); about 18,000 people were killed or went missing, most by drowning (1).
Question 38 · Spec 3.1.5.4 · Recent events
Tohoku, Japan, 2011: describe the impacts. [4 marks]
Answer:
Entire coastal towns were destroyed, with hundreds of thousands made homeless (1); the tsunami flooded the Fukushima Daiichi nuclear plant, causing meltdowns and the evacuation of around 150,000 people (1); ports, roads, railways and industry were disrupted, affecting global supply chains (1); the damage cost over $200 billion, among the costliest natural disasters ever (1).
Question 39 · Spec 3.1.5.4 · Recent events
Tohoku, Japan, 2011: describe the responses. [3 marks]
Answer:
Early warning stopped trains and gave coastal residents time to evacuate (1); the Self-Defense Forces and international teams carried out rescue and relief (1); reconstruction included higher sea walls, relocation to higher ground and tougher nuclear safety rules (1).
Question 40 · Spec 3.1.5.4 · Recent events
Nepal (Gorkha), 2015: describe the nature of the earthquake. [3 marks]
Answer:
A magnitude 7.8 earthquake on 25 April 2015, with a shallow focus (1); caused by the Indian plate moving north beneath the Eurasian plate (1); a large aftershock of magnitude 7.3 followed on 12 May (1).
Question 41 · Spec 3.1.5.4 · Recent events
Nepal (Gorkha), 2015: describe the impacts. [4 marks]
Answer:
Nearly 9,000 people died and around 22,000 were injured (1); more than 500,000 homes were destroyed (1); historic sites in Kathmandu were damaged, and an avalanche on Everest killed 19 climbers and guides (1); landslides blocked roads, and the cost was about a third of the country's GDP (1).
Question 42 · Spec 3.1.5.4 · Recent events
Nepal (Gorkha), 2015: describe the responses and the problems. [3 marks]
Answer:
International teams, India and the UN provided rescue, aid and medical help (1); remote villages were hard to reach because of landslides and poor roads (1); rebuilding was slow, and years later many people still lacked permanent homes (1).
Question 43 · Spec 3.1.5.4 · Recent events
Christchurch, New Zealand, 2011: describe the nature and impacts. [4 marks]
Answer:
A magnitude 6.3 earthquake on 22 February 2011 with a shallow focus (1); its epicentre was very close to the city centre, so shaking was extreme (1); 185 people died, over 100 of them in one collapsed office building (1); liquefaction damaged thousands of homes, and parts of the city centre were closed off for years (1).
Question 44 · Spec 3.1.5.4 · Recent events
Turkey and Syria, 2023: describe the nature of the earthquakes and their impacts. [4 marks]
Answer:
A magnitude 7.8 earthquake on 6 February 2023 on the East Anatolian Fault, followed hours later by a magnitude 7.5 earthquake (1); more than 50,000 people were killed across the two countries (1); tens of thousands of buildings collapsed or were badly damaged (1); millions of people were left homeless in the cold of winter (1).
Question 45 · Spec 3.1.5.4 · Recent events
Turkey and Syria, 2023: explain why the death toll was so high. [3 marks]
Answer:
Many buildings were poorly built and did not meet the seismic building codes (1); the earthquake struck at night while people were asleep (1); in north-west Syria, the war had already damaged homes and health services, and aid was slow to arrive (1).
Question 46 · Spec 3.1.5.4 · Recent events
Turkey and Syria, 2023: describe the responses. [3 marks]
Answer:
International search and rescue teams were sent, and countries gave aid (1); a state of emergency was declared in Turkey, and tent cities and containers housed survivors (1); contractors were investigated for breaking building rules, and rebuilding programmes began (1).
Question 47 · Spec 3.1.5.4 · Recent events
Compare the impacts of the Tohoku 2011 and Nepal 2015 earthquakes. [4 marks]
Answer:
Tohoku was a larger event and caused a massive tsunami (1); it killed fewer people than expected for its size because of preparedness and warning (1); Nepal's lower magnitude earthquake destroyed far more homes in proportion, because buildings were weaker (1); Nepal depended on international aid and recovered more slowly, but Japan had greater economic cost (1).
Question 48 · Spec 3.1.5.4 · Recent events
Explain why large cities close to plate boundaries, such as Tokyo or San Francisco, are at high risk from earthquakes. [3 marks]
Answer:
They lie close to active faults or subduction zones (1); high population density and tall buildings put many people at risk (1); infrastructure such as gas, electricity and transport is concentrated and easily damaged (1).
Question 49 · Spec 3.1.5.4 · Responses
Explain why the death toll from the same size of earthquake can differ between countries. [3 marks]
Answer:
Strong building codes, enforced and applied to new and old buildings, reduce collapse (1); preparedness, drills and warnings help people to protect themselves (1); wealthy countries have better emergency services, hospitals and ways to reach survivors quickly (1).
Question 50 · Spec 3.1.5.4 · Forms of hazard
Describe the main features of a tsunami. [2 marks]
Answer:
In deep ocean it travels at over 700 km/h and is barely noticeable at the surface (1); in shallow water it slows and builds into waves many metres high, with a long wavelength and a powerful surge (1).

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