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Joint Meeting Pacific Section, AAPG & Cordilleran Section GSA April 29–May 1, 2005, San José, California

Analysis of Hazard, Vulnerability, Population, and Infrastructure

David G. Howell
Circum Pacific Council, c/o USGS, ms 973, Menlo Park 94025, [email protected]

Many of the Earth's natural hazards remain relatively constant, but exploding populations and unprecedented urban development within the past century have helped fuel an increase in the number and severity of disasters. Moreover, networks of people, information, and commodities now traverse great distances to serve even larger concentrations of people. Understanding the risks posed by these increasingly connected populations by natural hazards therefore requires an expanded regional analysis. To better understand the “future of disasters” for the Circum Pacific region, potential impact of five significant natural hazards were calculated: earthquake, flood, tropical storm, tsunami and volcanic eruption. For each individual hazard the vulnerability of people and infrastructure were estimated separately. Risk is estimated by using the relationship: Risk = f (H, E, V) where H is a combined relative index of hazard probability; E is a relative index ranking the elements at risk (people vs. infrastructure); and V, vulnerability, is a relative index measuring resilience during a disaster for the two elements. An additional component in the measurement of risk may prove useful in the future; a measure of interconnectivity or interdependence - the dynamic linkages of people, information and commodities in a ‘globalized' social and economic system.

The risk assessment for people and infrastructure reflect different repercussions from natural disasters: losses of life and disruption of economic activity. Because population and infrastructure are distributed heterogeneously across the Pacific Rim region, two contrasting portraits of risk emerge: human populations are most vulnerable and most at risk in “developing” countries while high-valued infrastructure is at risk in “developed” countries. The December 26, 2004 tsunami in the Indian Ocean seems to portray the vulnerability of the first of these two risk-portraits in a most devastating fashion.

Posted with permission of The Geological Society of America; abstract also online ( © Copyright 2005 The Geological Society of America (GSA).