While earthquakes cannot be prevented, their effects can be reduced by assessing risks and preparing appropriately. Risk assessment requires (1) determining the probability that a major quake will occur and (2) studying the susceptibility of soils to severe shaking. Once such information is obtained, existing structures can be reinforced, if necessary, and building codes for new structures can be revised.
Because long periods of time pass between damaging earthquakes in this region, it is easy for us to become complacent. Studying the stresses, strains, and movements of masses of rock kilometers below the surface of the Earth presents problems of immense complexity for scientists, but until those problems are solved we cannot know when a major earthquake will occur.