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Author: William H. Hooke
Engineers are in the business of improving public health and safety, facilitating economic growth, protecting the environment and ecosystems, and providing for national security. And, they attempt to accomplish all of this on a planet that does its business through extreme events. The earthquakes we experience are crustal manifestations of Earth’s continental drift. “Climate” is really the aggregate of patterns and statistics of extremes of heat and cold, flood and drought. What we call climate variability, or climate change, is really a change in those patterns.
Disasters occur at the intersection between natural extremes and human populations and the built environment. Thus they are social constructs, not the results of natural hazards alone. Disasters are about centuries of decisions—especially about where and how to build—with an overlay of cultural and ethnic preferences, demographics, and economic decisions for developing and allocating wealth. Thus they are not solely a matter of emergency response.
NAE recently sponsored a symposium on engineering for the threat of natural disasters. Engineering for the threat of natural disasters is a broad topic, and the papers in this issue cannot possibly do the topic full justice. However, they can stimulate discussion and ideas for the future. The first three articles, which are based on presentations given at the symposium, draw lessons from three recent natural disasters: Hurricane Katrina (by John Christian), the Indian Ocean tsunami in 2004 (by Lloyd Cluff), and the earthquake in Pakistan in 2005 (by Melvyn Green).
In John Christian’s review of engineering studies related to Katrina, he describes several plausible explanations for levee failures in New Orleans. He concludes that a number of mechanisms were at work and that it is impossible to place the blame on any one of them. He calls for better engineering in the future, external peer reviews of both designs and construction, and more rigorous analysis of what went wrong with the evacuations.
Lloyd Cluff provides a crisp summary of the December 26, 2004, tsunami and its aftermath, based largely on his own on-site survey and analysis. In the midst of the general devastation, he found numerous examples of sound engineering and construction that withstood both the earthquake and the tsunami waves.
Melvyn Green surveys types of owner-built structures in seismic areas. As he points out, improving building performance of existing owner-built buildings constructed with site-found materials would greatly reduce earthquake fatalities and damage. He suggests that improvements will require that nations work cooperatively to provide information to home owners and builders.
Because disasters are the results of social decisions, engineering strategies must be integrated with social-science and natural-science strategies. In addition, political leaders, NGOs, civic leaders, and many others must be involved in disaster preparedness and response. The paper by Tom O’Rourke, which is based on a presentation given at a colloquium on infrastructure and disaster-resilient communities, explains how resiliency fits into the continuum of responses and its implications for public policy.
As Hurricane Katrina demonstrated, engineering for the threat of natural disasters is not a matter for the public sector alone (whether at the local, state, or federal level). The private sector also plays a pivotal role. Private enterprise is a victim, an emergency responder, a mitigation planner, and a vector for propagating the effects of a disaster far beyond the area directly impacted. The private sector also operates much of the nation’s critical infrastructure—communications, electrical and gas utilities, certain elements of water and transportation systems, and soft infrastructure, such as health care and financial facilities. In the final paper, Yossi Sheffi defines the characteristics of disaster-resilient enter-prises. He argues that a comprehensive strategy for disaster preparedness must bring to bear the assets and issues of the private sector.
Finally, because disasters are social constructs that mutate in response to social change—population increases and urbanization, the globalization of business, and advances in science and technology—engineers are faced with a moving target. Consider hurricanes. A century ago, they exacted a huge toll in lives because they were difficult to detect prior to landfall. Advances in monitoring and forecasting, beginning with ship-borne radio, changed that. A century ago, disasters were measured in fatalities and damaged and destroyed structures. However, urbanization, made possible by the development of critical infrastructure—communications, electrical power, gas, sewage, transportation, and water—has transformed the challenge. Hurricane disasters today are counted not only in fatalities and loss of physical property, but also in economic disruption. Hurricane Katrina, for example, triggered a spike in local—and national—gasoline prices. If the port of New Orleans had been compromised, countries worldwide would have experienced disruptions in shipments of U.S. grain.
Other examples are the New Madrid earthquakes of 1812 and the threat from space weather. The New Madrid earthquakes of 1812, the strongest this nation has ever experienced, discommoded a relative handful of fur traders and villages of indigenous peoples. Today, much of the natural gas infrastructure that supports the Northeast passes through that region. Space weather represents another entirely new vulnerability that did not exist prior to the invention of the telegraph and our dependence on electrical energy and regional power grids, long pipelines, and spaced-based technologies, such as weather monitoring, telecommunications, GPS, and transpolar flights.
The engineering community holds the keys to the future—which lies somewhere on a spectrum between a world in which natural hazards are a diminishing threat and a darker world in which natural extremes and disasters will seal the human fate.