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THE EARTHQUAKE HAZARD Earthquakes occur as a result of sudden displacements across a fault within the earth. The earthquake releases part of its stored strain energy as seismic waves. These waves propagate outward and along the earth’s surface. It is the motion of the ground as these waves move past that is perceived as an earthquake. With most earthquakes, ground shaking is the direct and principal cause of damage to buildings and infrastructure. Considerable damage can be caused by fault rupture at the surface, but this is generally limited to places near the fault.

Sometimes indirect shaking effects such as tsunamis, landslides, fire caused by gas-line breaks, and flooding caused by water-line breaks also play a significant role. Although fewer than 150 lives have been lost in the United States since 1975 as a result of earthquakes (Cutter, 2001), the potential for economic loss and social disruption is enormous (Mileti, 1999). Recent California earthquakes of even moderate magnitude, such as the Loma Prieta earthquake in 1989 and the Northridge earthquake in 1994, caused damage ranging up to $30 billion (). While the seismic risk is highest in California, other regions as geographically dispersed as western Washington state, Alaska, Utah, South Carolina, the midcontinent, and areas around Boston, the St. Lawrence Seaway, and New York City all have significant potential for earthquake-related damage and economic loss. Studies conducted by the U.S.

Geological Survey demonstrate that except for Texas, Florida, the Gulf Coast, and the upper Midwest, most of the United States is at some risk from earthquakes (USGS, 2002). Sidebar 1.2 A Note on Annualized Risk Earthquake risk is often expressed on an annualized basis; that is, the cost of an event with an expected frequency of once in x years is discounted as an equal annual cost over that period. However, such first-order economics are somewhat misleading when applied to catastrophic earthquake losses. Although the expected annualized losses may be accurately calculated at, say, $4 billion (a figure that appears quite manageable within a $10 trillion economy), in reality the losses from a single catastrophic earthquake could approach 30 to 50 times that amount.

Thus, the potential effects on the national economy of a loss of such magnitude—which could, among other things, bankrupt the property insurance industry—would seem inadequately represented by an annualized loss estimate. EARTHQUAKE ENGINEERING RESEARCH, THE NATIONAL SCIENCE FOUNDATION, AND NEES Widespread concern following the Good Friday earthquake in Alaska in 1964, the Niigata earthquake in Japan in the same year, and the San Fernando earthquake in California in 1971 prompted the research that has since led to significant progress in understanding the nature of earthquakes and the application of this knowledge to the planning, design, and construction of earthquake-resistant structures. Over the past 30 years our understanding of the causative structure of earthquakes, the fundamentals of earthquake mechanisms, and earthquake-resistant design and construction practices has markedly improved. Reshebnik po garmonii dubovskij evseev sposobin sokolov. Decades of research and learning from all historical earthquakes have contributed to numerous successes in earthquake engineering, a few of which are discussed later in this chapter.

Lists significant discoveries that have helped to reduce earthquake losses. Outlines potential benefits of earthquake engineering research. The Network for Earthquake Engineering Simulation (NEES) Another way in which the NSF has led in the development of a national program for basic earthquake engineering research is through the George E. Brown, Jr., Network for Earthquake Engineering Simulation (NEES). The goal of the NEES Program is to provide a networked national resource of geographically distributed, shared-use, next-generation experimental research equipment installations, with teleobservation and teleoperation capabilities, which will shift the emphasis of earthquake engineering research from current reliance on physical testing to integrated experimentation, computation, theory, databases, and model-based simulation. NEES will be a collaboratory, i.e., an integrated experimental, computational, communications, and curated repository system, developed to support collaboration in earthquake engineering research and education (see ).