Photo by: Don Eggert
Seismologists are far from a complete understanding of the inherently chaotic process of earthquake triggering, which has prevented them from being able to predict when earthquakes will occur. Therefore, no one can say with any certainty when or if an earthquake strong enough to cause significant property damage, injury, or loss of life in Indiana will occur. However, considering the prehistoric evidence of strong earthquakes with epicenters within Indiana, the history of earthquakes that have caused damage in Indiana since 1811, and the presence of compressional forces squeezing the rocks at great depths under the state, it is reasonable to conclude that we do indeed face the possibility of experiencing the potentially devastating effects of a major earthquake at some point in the future.
Preparing for the next quake
While we can't prevent earthquakes, we can reduce their disastrous effects by assessing the risks and preparing for them. Assessing risks involves determining the probability of the occurrence of an earthquake within a particular region, and may also involve determining how susceptible the soils of that region are to severe ground shaking. The composition, structure, and thickness of a soil, which may vary greatly from one location to another, even within a small area, determines how it will behave during an earthquake. Accurate assessment of an area's level of risk requires the collection and careful study of information about local geology and the engineering properties of the soil. This information can then be used to determine where and how structures should be built and which existing structures should be reinforced within the study area.
As long as compressional forces continue to squeeze the rocks beneath the surface of the central United States, earthquakes will occur. Because great periods of time pass between occurences of damaging earthquakes in this region, it is easy for us to become complacent and consequently inadequately prepared. 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, or even if, a major earthquake will occur. But, if it does occur, wouldn't it be better to be prepared?
Preparing for an earthquake includes constructing critical structures such as schools, hospitals, dams, and bridges so that they are able to survive the maximum level of shaking likely to occur at the site; developing a plan for coordination of activities among emergency response agencies; developing plans of action for schools, businesses, and homes; and educating everyone about earthquakes and what can be done to lessen their potentially disasterous effects.