we are threatened by earthquake.( active)
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Facing the Earthquake Threat
Earthquakes rival all other natural disasters inthethreat they pose to human life and habitat. Unlike floods, hurricanes, and volcanic eruptions, specific earthquakes cannot be predicted with the short-term accuracy required for effective emergency management. The science is now capable of identifying where earthquakes will happen and how big they might be, but such forecasts are valid only for intervals measured in decades or even centuries. Once an event has occurred, there is very little time for warning and action; the fast-moving seismic ground waves do most of their damage in a macroseismic zone within the first minute or so after the rupture nucleates (1). Preparation and rapid emergency response are therefore the bulwarks of a good seismic defense. This chapter describes the context of current efforts to improve seismic safety and performance by summarizing what is known about the principal types of earthquake hazards, their distribution across the nation and the world, and the knowledge-based approaches to reducing earthquake risk. It concludes by addressing the issue of how scientists can help to implement the knowledge gained through research by stimulating civic actions that actually reduce risk.