Geography · Year 7 · The Restless Earth: Geomorphology · Autumn Term

Earthquakes: Causes and Measurement

Studying the causes of earthquakes, seismic waves, and methods of measurement and prediction.

• National Curriculum Attainment Targets
• KS3: Geography - Physical Processes: Geological Processes

About This Topic

Earthquakes arise from sudden releases of energy along faults in the Earth's crust, mainly at tectonic plate boundaries where plates converge, diverge, or slide past each other. Year 7 students examine how convection currents in the mantle drive plate movement, building stress that fractures rock and sends out seismic waves: fast primary (P) waves, slower secondary (S) waves, and destructive surface waves. They distinguish magnitude scales, such as the Richter or moment magnitude which quantify energy logarithmically, from intensity scales like the Modified Mercalli that gauge local effects through human observations.

This content aligns with KS3 physical processes in geography, particularly geomorphology, and supports skills in analysing spatial data and evaluating hazard management. Students plot epicentres using wave arrival times from seismograms and assess prediction methods like monitoring foreshocks or ground deformation, alongside preparedness such as building codes and early warning systems.

Active learning excels with this topic because abstract plate dynamics and wave propagation become concrete through tactile models and data handling. When students push tectonic plate simulations or triangulate epicentres from class-shared data, they internalise causes and measurement intuitively, while role-playing preparedness builds critical evaluation skills.

Key Questions

1. Explain how tectonic plate movement generates earthquakes.
2. Compare the different scales used to measure earthquake intensity and magnitude.
3. Assess the effectiveness of current earthquake prediction and preparedness strategies.

Learning Objectives

• Explain the mechanism by which convection currents in the Earth's mantle cause tectonic plate movement.
• Compare the logarithmic nature of magnitude scales (e.g., Richter) with the descriptive nature of intensity scales (e.g., Modified Mercalli).
• Analyze seismogram data to triangulate the epicenter of an earthquake.
• Evaluate the reliability and limitations of different earthquake prediction methods.
• Design a basic preparedness plan for a community facing seismic risk.

Before You Start

Earth's Structure and Layers

Why: Understanding the different layers of the Earth (crust, mantle, core) is fundamental to grasping plate tectonics and how seismic waves propagate.

Basic Map Skills and Coordinates

Why: Students need to be able to interpret maps and understand coordinate systems to plot earthquake epicenters.

Key Vocabulary

Tectonic Plates	Large, rigid slabs of rock that make up the Earth's outer layer, constantly moving and interacting with each other.
Fault	A fracture or zone of fractures between two blocks of rock, where movement has occurred.
Seismic Waves	Vibrations that travel through the Earth's layers, originating from the sudden release of energy during an earthquake.
Epicenter	The point on the Earth's surface directly above the focus, or origin, of an earthquake.
Magnitude	A measure of the energy released by an earthquake, typically quantified using scales like the Richter or moment magnitude scale.
Intensity	A measure of the effects of an earthquake at a particular place, based on observed damage and human reactions, using scales like the Modified Mercalli scale.

Watch Out for These Misconceptions

Common Misconception

Earthquakes can occur randomly anywhere on Earth.

What to Teach Instead

Most earthquakes cluster at tectonic plate boundaries due to stress from plate movements. Mapping global quake data in groups reveals these patterns clearly, helping students shift from random views to plate-driven models through visual evidence and peer discussion.

Common Misconception

The Richter scale measures the damage caused by an earthquake.

What to Teach Instead

Richter measures total energy released at the source, while Mercalli assesses local shaking effects. Comparing data tables and photos in stations allows students to see why distant areas feel less despite high magnitude, correcting the mix-up via hands-on analysis.

Common Misconception

Animals or unusual behaviours reliably predict earthquakes.

What to Teach Instead

No scientific evidence supports animal prediction over monitored precursors like foreshocks. Debating case studies in pairs encourages students to evaluate anecdotal claims against data from seismometers, building skills in evidence-based reasoning.

Active Learning Ideas

Modelling: Fault Formation with Jelly

Prepare trays with layered jelly over golden syrup to represent crust and mantle. In small groups, students apply sideways, pulling, or upward forces to simulate plate boundaries and trigger 'earthquakes'. Sprinkle cocoa on top to visualise surface waves, then measure and sketch fault types. Conclude with a class share-out linking to real plate margins.

35 min·Small Groups

Jigsaw: Types of Seismic Waves

Divide class into three expert groups: one for P waves, one for S waves, one for surface waves. Each researches speed, effects, and detection using provided diagrams and videos. Experts then teach their wave type to new home groups, who create comparison tables. Finish with a whole-class wave speed sorting activity.

45 min·Small Groups

Stations Rotation: Magnitude vs Intensity

Set up three stations with historical earthquake data cards: one for plotting Richter magnitudes, one for Mercalli intensity maps, one for damage photos. Pairs rotate, recording differences and patterns. Groups present one key comparison to the class, using a shared whiteboard for visuals.

40 min·Pairs

Triangulation: Locating Epicentres

Provide printed seismograms from three stations. Individually, students measure P-S wave arrival differences to calculate distances, then plot circles on a map to triangulate the epicentre. Pairs check and discuss accuracy before a whole-class reveal with real event overlay.

30 min·Individual

Real-World Connections

• Seismologists at the British Geological Survey use seismograph networks to monitor seismic activity across the UK and globally, providing data for hazard assessments and public safety warnings.
• Structural engineers in earthquake-prone regions like California and Japan design buildings and infrastructure to withstand seismic forces, incorporating lessons learned from past earthquakes such as the 1995 Kobe earthquake.
• Emergency management agencies, like FEMA in the United States, develop and implement earthquake preparedness plans, including public education campaigns and early warning systems, to mitigate the impact of seismic events.

Assessment Ideas

Exit Ticket

Provide students with a simplified seismogram showing P and S wave arrival times from three different locations. Ask them to: 1. Identify which wave arrived first at each station. 2. Explain how they would use this information to locate the epicenter.

Discussion Prompt

Pose the question: 'If we could perfectly predict when and where an earthquake will happen, what are the top three actions a city should take to prepare?' Facilitate a class discussion, encouraging students to justify their choices based on the effectiveness and feasibility of different preparedness strategies.

Quick Check

Present students with two earthquake scenarios: one describing the damage and shaking felt (intensity) and another stating the energy released (magnitude). Ask students to identify which description corresponds to magnitude and which to intensity, and to briefly explain why.

Frequently Asked Questions

What causes earthquakes at tectonic plate boundaries?

Convection currents in the mantle cause plates to move, creating stress at boundaries: compression at destructive margins, tension at constructive, shearing at conservative. This stress releases suddenly along faults, generating seismic waves. Students benefit from models showing these interactions, linking daily observations of landforms to global processes in the National Curriculum.

How do magnitude and intensity scales differ?

Magnitude scales like Richter or moment magnitude measure the earthquake's total energy release on a logarithmic scale, consistent worldwide. Intensity scales like Modified Mercalli describe local effects based on human perception and damage. Teaching with data stations helps students plot and compare, clarifying why effects vary by distance and building map skills.

How can active learning help students understand earthquakes?

Active approaches like building jelly fault models or triangulating epicentres from seismograms make invisible processes visible and engaging. Small group rotations with data stations promote collaboration and deeper retention, while simulations of plate pushes reveal wave mechanics intuitively. These methods align with KS3 enquiry skills, turning abstract concepts into memorable, skill-building experiences.

Why is earthquake prediction challenging?

Precise prediction of time, place, and size remains unreliable due to complex fault mechanics, though monitoring foreshocks, GPS deformation, and gas emissions provides probabilities. Preparedness focuses on early warnings and resilient infrastructure. Role-play activities let students assess strategies, fostering critical thinking about risk reduction in geography.