After the shaking: the secondary hazards of earthquakes

The secondary hazards of earthquakes

Secondary hazards caused by earthquakes, such as tsunamis, landslides and soil liquefaction, can have a greater impact than the seismic shaking of the initial quake. This article looks at the different types of secondary hazard, their impacts and what can be done to plan for them. It will boost your understanding of plate tectonics and natural hazards

Alexander Densmore and Brett Cherry

Factory barracks in northern Sichuan after the 2008 earthquake. The barracks survived the earthquake with minimal damage, but the entire ground floor was buried by sediment during aggradation of the nearby river

Since 1900, earthquakes have killed over 2 million people worldwide. Damaging earthquakes occur every year, with predictable effects — the abrupt offset of the ground surface and violent shaking that can disrupt the lives of thousands to millions of people in just a few minutes.

But earthquake hazards are not limited to the seismic shaking of the Earth’s surface. Earthquakes also cause a range of other effects that we call secondary hazards, including tsunamis, landslides and debris flows. These can be at least as deadly as the main shock of the earthquake itself, and they can be more difficult to prepare for and to recover from. This article looks at some of the most common secondary hazards, and suggests scientists and governments need to do more to prepare for them.