An earthquake can trigger landslides, liquefaction and tsunamis. Damage then spreads through roads, water, power and other essential services.
Ground shaking can collapse vulnerable buildings, damage bridges and break pipes. Falling objects and structures can injure or kill people. Damage to water, transport and power networks then disrupts healthcare, communication and business beyond the first damaged site.
Liquefaction is a temporary loss of ground strength. Strong shaking raises water pressure between grains in loose, saturated sediment. The grains support one another less effectively, so buildings may sink or tilt and buried pipes may move or rise. The soil has not melted; the process depends on the sediment and water conditions.
Shaking can destabilise slopes and trigger landslides. These may bury settlements, damage habitats, block roads or dam rivers. Blocked roads delay rescue. A temporary landslide dam may later fail and cause flooding. Slope angle, rock condition and water affect how easily failure occurs.
A tsunami is a series of long waves caused by sudden, large water displacement. An undersea earthquake can trigger one if it moves enough seabed and overlying water, especially vertically. Not every submarine earthquake does this. Tsunami waves can cross an ocean and create dangerous flooding and currents near coasts.
Tsunamis damage habitats and buildings, move debris, contaminate water and disrupt ports and livelihoods. These effects can occur far from the earthquake. Keep the chain clear: earthquake, secondary hazard, then wider social or environmental losses.
Step by step
Shaking destabilises a slope
An earthquake can trigger a landslide.
The landslide blocks a road
People, supplies and vehicles lose an access route.
Help is delayed
A physical hazard becomes a wider disruption to rescue and essential services.
Worked example: Why wet ground matters
In an illustrative riverside district built on loose saturated sand, strong shaking raises pore-water pressure and reduces ground strength. Buildings can tilt and pipes break. The same shaking on different ground may produce a different pattern of damage.
Watch out for this
Every earthquake under the ocean makes a tsunami.
A tsunami needs substantial water displacement. Earthquake size, depth and the direction and extent of seabed movement matter.
Check your understanding
Buildings tilt on loose saturated ground after shaking. Which explanation best fits liquefaction?
- Raised pore-water pressure reduces support between grains.
- Friction instantly melts the whole soil layer into magma.
- A tsunami must have occurred at every damaged building.