Eduqas GCSE Geology Human interaction with the Earth: hazards, resources and engineering geology

What this module actually demands

Human interaction with the Earth is the applied module: it takes the processes and materials from the rest of the course and asks how they affect people, and how people respond. Eduqas tests three linked areas: the natural hazards (earthquakes, volcanoes and mass movement) and how they are predicted and mitigated; the resources we extract (metal ores, oil and gas, and groundwater) and the economics and rock properties behind them; and engineering geology, assessing the ground before we build. The skill is applying earth science to real situations and evaluating what should be done, which is exactly what the higher-mark AO2 and AO3 questions reward. This overview ties the six dot-point pages together; each has its own page with worked exam questions.

Earthquake hazards and prediction

Earthquakes are the sudden release of strain when a locked fault slips, mostly at plate margins. Fast P-waves arrive before slow S-waves, and because the gap grows with distance, it gives the distance to each station; three stations fix the epicentre. Magnitude comes from the wave amplitude on a logarithmic scale. Hazards include shaking, building collapse (the main killer), tsunamis, fires, landslides and liquefaction. Precise prediction is impossible, so forecasting uses probability from past records, and the real defences are earthquake-resistant building design, hazard mapping and emergency planning. The same magnitude can be far deadlier in an unprepared city.

Volcanic hazards and monitoring

Silica content sets magma viscosity and gas escape: low-silica basalt is runny and erupts gently (shield volcanoes); silica-rich magma is viscous, traps gas, and erupts explosively (composite volcanoes). Hazards include lava flows, ash falls, pyroclastic flows (the deadliest), lahars and toxic gases. Volcanoes are more predictable than earthquakes because rising magma gives building warning signs, earthquake swarms, ground bulging, rising gas and temperatures, that monitoring detects, allowing exclusion zones and evacuation.

Mass movement hazards

A slope stays stable while the resisting force (friction and cohesion) exceeds the driving force (gravity), and fails when the driving force wins. Heavy rain is the classic trigger: it adds weight (more driving force) and lubricates grains and raises pore pressure (less resisting force); undercutting, loading, earthquakes and weak clay also tip the balance. Risk is reduced by drainage (usually best), reducing the slope angle, retaining structures, vegetation, and avoiding unstable ground, all of which lower the driving force or raise the resisting force.

Resources: ores, hydrocarbons and groundwater

An ore is a deposit from which a metal can be extracted economically; metals are concentrated by hydrothermal, magmatic and weathering processes, and whether a deposit is mined depends on grade, size, depth and price against cost. Oil and gas form in a source rock, migrate into a porous, permeable reservoir, and are held by an impermeable cap rock and a trap. Groundwater is stored in a porous, permeable aquifer below the water table. Both depend on porosity (storage) and permeability (flow), and both can be over-exploited or polluted.

Engineering geology

Before building, the ground is investigated so that foundations, tunnels, dams and reservoirs suit the rock present. Geologists check rock strength, faults, slope stability, permeability (a reservoir must hold water; a tunnel should stay dry) and the hazards of weak, soluble or swelling materials. Ignoring the geology causes subsidence, leakage, collapse or failure, so a site investigation (boreholes, plus maps and cross-sections) always comes first.

The exam patterns Eduqas repeats

• Locate an earthquake. Use the P-S gap for distance and three stations for the epicentre; a recurring quantitative question.
• Explain why impacts differ for the same magnitude. Building quality, preparedness and ground conditions.
• Link magma silica to eruption style and give matched hazards and monitoring methods.
• Apply the driving-versus-resisting force balance to a failing slope, especially the role of water.
• Define an ore economically and explain why a deposit's status changes with price and cost.
• Build a petroleum trap (source, reservoir, cap, trap) and contrast porosity with permeability.
• Assess a site for a reservoir, tunnel or foundation and state what goes wrong if the ground is unsuitable.

How to revise this module

1. Drill the epicentre method. Practise reading distance from a P-S gap and fixing the epicentre from three circles until it is automatic.
2. Make a hazards table. For earthquakes, volcanoes and mass movement: cause, hazards, how it is monitored or predicted, and how risk is reduced.
3. Learn magma silica versus eruption style and the four volcano-monitoring methods.
4. Memorise the force balance for slopes and the dual role of water, then rehearse stabilisation measures with their mechanisms.
5. Learn the ore definition and the petroleum-trap elements, and the porosity-versus-permeability distinction.
6. Practise site-investigation questions for a reservoir, tunnel and building, each with the key factor and the consequence of ignoring it.

Use the six dot-point pages for the detail and worked exam questions; this guide is the map that connects them.