Eduqas GCSE Geology · 4.1

Earth Hazards and their Mitigation

50 revision questions with answers for 4.1 Earth Hazards and their Mitigation in Eduqas GCSE Geology (spec C480QS). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, Five Degrees, Associations, or read every question and answer below. Not official Eduqas material.

All 50 questions and answers

Question 1
What is a geological hazard?
Answer:
A geological event or process with the potential to cause harm, damage or disruption.
Question 2
What is risk in relation to a geological hazard?
Answer:
The likelihood and potential consequences of harm, affected by hazard, exposure and vulnerability.
Question 3
Why can the same earthquake pose different risks in two places?
Answer:
Population, building quality, preparedness and local ground conditions can differ.
Question 4
How does population density affect hazard risk?
Answer:
More people and property may be exposed in a densely populated area.
Question 5
How can education reduce hazard risk?
Answer:
People who know warning signs and evacuation procedures can respond more effectively.
Question 6
How can communication affect hazard risk?
Answer:
Reliable warnings can reach people quickly and allow them to evacuate or take shelter.
Question 7
Why can economic development influence risk?
Answer:
Resources for monitoring, resilient buildings and emergency response can reduce vulnerability, though risk still varies.
Question 8
What causes earthquake shaking?
Answer:
Sudden movement on a fault releases energy as seismic waves.
Question 9
How can an earthquake trigger a landslide?
Answer:
Ground shaking can destabilise a slope and cause rock or sediment to move downhill.
Question 10
Why can soft sediment increase earthquake damage?
Answer:
It can amplify shaking or, if water-saturated and loose, undergo liquefaction.
Question 11
How can building design reduce earthquake damage?
Answer:
Flexible frames, reinforcement and base isolation help buildings withstand or absorb shaking.
Question 12
Why are building regulations important in earthquake zones?
Answer:
They require structures to meet standards intended to reduce collapse and injury.
Question 13
What is a seismic gap?
Answer:
A section of an active fault that has been relatively quiet compared with adjacent sections and may be accumulating strain.
Question 14
Can a seismic gap predict an earthquake's exact date?
Answer:
No. It indicates possible elevated long-term concern, but exact timing remains uncertain.
Question 15
What is the difference between forecasting and exact prediction?
Answer:
Forecasting estimates probability over an area and period; exact prediction would specify time, place and magnitude.
Question 16
Why are earthquake warning systems useful even if they do not predict events in advance?
Answer:
Detection of an initial rupture may provide seconds of warning before stronger shaking arrives at some locations.
Question 17
What information is needed to compare earthquake risk between two towns?
Answer:
Hazard likelihood and shaking, population exposure, building vulnerability and capacity to respond.
Question 18
Name four hazards associated with volcanic eruptions.
Answer:
Lava flows, ash fall, pyroclastic flows and volcanic mudflows.
Question 19
What is a pyroclastic flow?
Answer:
A fast-moving, hot mixture of gas, ash and rock fragments flowing down a volcano.
Question 20
What is a volcanic mudflow, or lahar?
Answer:
A flow of water mixed with volcanic ash and debris, often moving down river valleys.
Question 21
Why can volcanic ash be hazardous far from a volcano?
Answer:
Wind can carry fine ash widely, affecting breathing, buildings, water supplies and aircraft.
Question 22
Why are fast pyroclastic flows especially dangerous?
Answer:
They move rapidly, are very hot and can overwhelm people and structures.
Question 23
How can lava flow threaten property?
Answer:
It can bury, burn or cut off buildings, roads and farmland.
Question 24
How can a tiltmeter help monitor a volcano?
Answer:
It measures changes in ground slope that may indicate swelling or deflation of the volcano.
Question 25
Why monitor volcanic gas emissions?
Answer:
Changes in gas composition or output can provide evidence of magma movement, although they do not guarantee an eruption.
Question 26
How can groundwater changes contribute to monitoring?
Answer:
Changes in level, temperature or chemistry can indicate changes in volcanic activity or subsurface fluids.
Question 27
Why is combining several monitoring signals useful?
Answer:
Ground deformation, seismicity and gas changes together may provide stronger evidence than one uncertain signal.
Question 28
Earthquakes beneath a volcano become shallower as its flank bulges. Suggest an explanation.
Answer:
Rising magma may fracture rock at progressively shallower depths and inflate the volcano; continued monitoring is needed.
Question 29
How can a hazard map help reduce volcanic risk?
Answer:
It identifies areas likely to be affected by different hazards and supports planning and evacuation.
Question 30
Why should evacuation routes avoid valleys threatened by lahars?
Answer:
Mudflows can follow and rapidly fill river valleys.
Question 31
What is a landslide?
Answer:
Downslope movement of rock, soil or debris under gravity.
Question 32
How can heavy rain increase landslide risk?
Answer:
Water adds weight and can reduce effective friction or strength along slopes and slip surfaces.
Question 33
How can bedding dip affect slope stability?
Answer:
Beds dipping towards and out of a slope can provide potential sliding surfaces, especially if weak or wet.
Question 34
Why can joints and faults weaken a slope?
Answer:
They provide fractures along which blocks can detach or water can enter.
Question 35
Give two measures that can reduce rockfall risk at a cutting.
Answer:
Rock bolts, protective netting, drainage or reshaping the slope.
Question 36
What is subsidence?
Answer:
Downward movement of the ground surface, for example above underground voids or compacting material.
Question 37
How can abandoned underground workings cause subsidence?
Answer:
The roof of a void may collapse or the overlying ground may settle into it.
Question 38
Why is hazard risk different from the physical size of a landslide?
Answer:
A small slide near a road or town can cause more harm than a larger slide in an unoccupied area.
Question 39
What is a tsunami?
Answer:
A series of long-wavelength sea waves generated by sudden displacement of water.
Question 40
How can an undersea earthquake generate a tsunami?
Answer:
Sudden vertical movement of the sea floor displaces the overlying water.
Question 41
Can an underwater landslide generate a tsunami?
Answer:
Yes. A rapidly moving mass can displace a large volume of water.
Question 42
Why can a tsunami become taller near a coast?
Answer:
As the waves enter shallow water, they slow and their energy is compressed into a shorter wavelength and greater height.
Question 43
How can a tsunami warning reduce risk?
Answer:
Rapid detection and communication can give coastal populations time to move to higher ground.
Question 44
Why should people not assume the first tsunami wave is the largest?
Answer:
A tsunami consists of several waves and a later wave can be larger.
Question 45
What is a suitable immediate response to an official tsunami warning?
Answer:
Move promptly to designated high ground or inland using the local evacuation plan.
Question 46
A volcano threatens a remote area and a crowded city. Where is exposure greater?
Answer:
The city has greater exposure because more people and property are in the hazard area.
Question 47
Why might a poorer country experience greater losses from a similar event?
Answer:
Buildings, monitoring, communication or emergency resources may be more limited; specific local evidence is needed.
Question 48
What should an evaluation of a proposed hazard measure include?
Answer:
Its likely benefit, limitations, cost or practicality and the evidence relevant to the location.
Question 49
A warning reduces casualties but not all damage. Why?
Answer:
Evacuation can protect people, while buildings and infrastructure may remain exposed.
Question 50
Why is no hazard prediction method perfectly reliable?
Answer:
Natural systems vary, observations are incomplete and similar warning signals can have different outcomes.

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