change in hydrostatic pressure, erosion, and collision 
with floating debris. 
Coastal erosion seldom threatens lives, but the 
economic costs are high along the 2,700 miles where 
erosion is a critical problem (primarily along the 
Atlantic and Great Lake shorelines). Coastal erosion 
occurs when more shore zone material is removed 
than deposited.'*? It is a part of the natural shore- 
line process, but is a serious problem where develop- 
ment has occurred. As with all of the other hazards, 
the increase in potential hazard equates closely to 
the growing population in the coastal zone, especially 
since coastal land is demanding constantly higher 
prices. Erosion usually occurs through wind, water, 
gravity, or biological processes; ice may speed the 
process in the Great Lakes. Changing water level is 
the major long-term cause of erosion, but storms, 
with their attendant winds and waves, produce the 
most immediate and dramatic cases of erosion. 
Land subsidence, the sinking of surface ground, 
is a second hazard where the primary threat of loss 
is economic, although there can be loss of life in the 
rare circumstances where subsidence leads to failures 
of dams or levees. Subsidence of coastal lands leads 
to potential loss of low-lying lands to submergence, 
and even if not submerged the threat of flooding is 
increased.- Subsidence may also threaten a wide 
variety of construction and developments that have 
occurred on the affected property. The major causes 
of surface ground sinking in Alabama, California, 
Florida, Louisiana, Texas, and Washington are fluid 
withdrawals, hydrocompaction, and drainage of peat 
lands, while in Illinois, Michigan, New Jersey, New 
York, Ohio, and Pennsylvania the extraction of 
solids is an additional major problem. 
Landslides are an endemic problem in the United 
States; however, the greatest level of danger in the 
132 Per Bruun. “Beach Erosion and Coastal Protection,” in 
Rhodes W. Fairbridge (ed), Encyclopedia of Geomorphology. 
New York: Van Nostrand-Reinhold, 1968. 
coastal areas is in the Pacific States. A landslide is 
the “perceptible downslope movement of rock, 
debris, soil, or some combination of these mate- 
rials.” °° Because landslide-prone areas are aesthe- 
tically pleasing sites and rapid population growth has 
led to the development of marginally stable lands, 
the problems of loss of property and life are steadily 
increasing despite the strictly localized character of 
landslides. 
Avalanches are moving masses of ice and snow 
that accelerate as they flow down a mountainside 
until level or gently sloping land is reached. In the 
coastal zone, the only place where avalanches 
threaten is on the coast of Alaska. Because the popu- 
lation of Alaska tends to live in the narrow band 
of land between mountain and sea, the threat to 
property and life is relatively great, and it increases 
as the population mounts because of the necessity to 
use less advantageous areas for development. In an 
avalanche of any size, everything above ground level 
is swept away by the force of the moving materials. 
While both landslides and avalanches are caused by 
a variety of factors, they are especially related to 
earthquake activity, where they are major accessory 
phenomena. 
Volcanoes are a hazard along the coast of Alaska 
and in Hawaii. Volcanoes are openings in the earth, 
usually on the top or sides of a mountain from which 
issue molten rock or gas. The danger derives from 
lava flows (molten material), pyroclastic flows (glass 
and rock fragments suspended in gas), volcanic mud- 
flows (mixture of fine material and water), and ash 
falls (small fragments of rock temporarily suspended 
in air and deposited, according to size, by wind). 
Although the hazards from volcanoes are relatively 
localized and eruptions occur infrequently, the dan- 
ger is ever present. 
133 U.S. Department of Commerce, NOAA, Office of Coastal 
Zone Management. Natural Hazard Management. Washington, 
D.C., p. I-37. 
Elements of Natural Hazard Management 
As is usually true in the delivery of irnportant 
services to the public, many persons at all levels of 
government and in the private sphere are involved 
in the five elements of natural hazard management 
considered below: 
Prediction and Warning 
The activity most familiar to the general public, 
because of the activities of the National Weather 
Service (in the National Oceanic and Atmospheric 
Administration), involves the prediction of, and 
warning about, natural hazards. The type of predic- 
tion and warning required tends to divide along the 
lines of occurrences caused by atmospheric condi- 
tions and those caused by geologic conditions (al- 
though this is only a very general division and the 
overlap of factors cannot be dismissed) . 
The Weather Service has three hurricane forecast- 
ing centers, and the Department of Defense has one. 
These four centers are responsible for selected areas 
of the Pacific, Atlantic, Gulf of Mexico, and Carib- 
bean Sea. Through the use of sophisticated proce- 
dures and equipment, these centers are able to track 
hurricanes and generally forecast their impact. This 
equipment includes a massive telecommunications 
network, satellites, reconnaissance aircraft, ocean 
_ data buoys, radars, and high-speed computers. Each 
center’s forecasts and warnings are disseminated and 
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