Can buildings be made safe from earthquakes?
The two most important variables affecting earthquake damage are (1) the intensity of ground shaking caused by the quake coupled with (2) the quality of the engineering of structures in the region. The level of shaking, in turn, is controlled by the proximity of the earthquake source to the affected region and the types of rocks that seismic waves pass through en route (particularly those at or near the ground surface).
Generally, the bigger, closer, and shallower the earthquake, the stronger the shaking. But there have been large earthquakes with very little damage either because they caused little shaking in populated areas, or because the buildings were built to withstand that kind of shaking. In other cases, moderate earthquakes have caused significant damage either because the shaking was locally amplified, or more likely because the structures were poorly engineered.
Damage from earthquake results from
- Strength of shaking
- Length of shaking.
- Type of soil.
- Type of building.
- Resonant frequency of building.