What is the most credible event emergency preparedness measures should be based on for the central US?
This depends on what level of risk emergency managers are able “politically, morally, or legally” to accept. The USGS does not make these kinds of decisions; its job is to provide the best estimates of the probabilities of ground shaking amplitudes (i.e., provide the scientific basis on which others make decisions). Although some of the inputs have changed, estimates of the hazard (shaking) have not changed appreciably. This is largely because the shaking depends on many factors, so that changes in a few factors often have little affect.
