5.1: Introduction

Most of the hazards that concern emergency managers are environmental hazards, which are commonly classified as natural or technological. Natural hazards are extreme events that originate in the natural environment, whereas the technological hazards of concern to emergency managers originate in human controlled processes (e.g., factories, warehouses) but are transmitted through the air and water. The natural hazards are commonly categorized as meteorological, hydrological, or geophysical. The most important technological hazards are toxic chemicals, radiological and nuclear materials, flammable materials, and explosives.

The list of natural and technological hazards that could occur in the United States is much larger than can be addressed here. Accordingly, this chapter focuses on the hazard agents that most commonly confront local emergency managers. The first section addresses four meteorological hazards—severe storms (including blizzards), severe summer weather, tornadoes, and hurricanes. It also includes wildfires because these are significantly influenced by lack of rainfall. The second section describes three hydrological hazards—floods, storm surges, and tsunamis. The third section addresses geophysical hazards—volcanic eruptions, earthquakes, and landslides. The material in these three sections is drawn primarily from Alexander (1993), Bryant (1997), Ebert (1988), Federal Emergency Management Agency (1997), Hyndman and Hyndman (2005), Meyer (1977), Noji (1997), Scientific Assessment and Strategy Team (1994), and Smith (2001). The fourth section covers technological hazards, primarily toxic, flammable, explosive, and radiological materials. The material in these three sections is drawn primarily from Edwards (1994), FEMA (no date, a), Goetsch (1996), Kramer and Porch (1990), and Meyer (1977). The last section summarizes information on biological hazards. The material in this section is drawn primarily from World Health Organization (2004), World Health Organization/Pan American Health Organization (2004), and Chin (2000).

The chapter does not address emergencies caused by large, unexpected resource shortages, energy shortages being a prime example. Nor does it address slow onset disasters such as ozone depletion, greenhouse gas accumulation, deforestation, desertification, drought, loss of biodiversity, and chronic environmental pollution. For information on these long term hazards, see sources such as Kontratyev, Grigoryev and Varotsos (2002).