Earthquake simulator: buildings, soil and seismic response
QuakeSys is a free educational earthquake lab for exploring how a building responds to shaking. This earthquake simulator compares three structures, lets you adjust their properties and displays the evolution of movement and estimated damage. It supports introductory civil engineering, architecture and physics lessons, as well as independent learners interested in seismic protection.
Materials, soil and ground motion
Compare reinforced concrete, steel and masonry with different structural systems. Stiffness describes resistance to deformation; ductility describes the ability to deform without breaking. No material guarantees good performance on its own: configuration, strength, height and the demand placed on the structure also matter.
Explore rigid rock, dense soil, soft soil and a sedimentary basin. Each ground profile changes amplification and frequency characteristics in this model. Magnitude, distance, depth and duration help create scenarios; these inputs alone cannot predict real damage at a particular location.
Understanding PGA, PGD and seismic protection
PGA is peak ground acceleration, displayed in units of g. PGD is peak ground displacement, displayed in centimetres. They measure different aspects of shaking and do not translate directly into a building damage percentage. Natural frequency, damping and duration also influence the simplified response.
Base isolators allow relative movement between the ground and the building. A roof tuned mass damper aims to moderate part of the vibration. Benefits depend on system properties: enabling protection does not guarantee that collapse will be avoided. The report records the observed simulation results, including the time of collapse when it occurs.
A classroom comparison
- Run a scenario and keep its report as a reference.
- Change only the soil or one protection system, keeping other inputs fixed.
- Compare movement, estimated damage and collapse time; explain what changed.
This heuristic model illustrates concepts. It does not assess the safety of an actual building, predict earthquakes or replace professional structural engineering analysis.
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