Textl GEOLOGIC HAZARDS

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There are no geologic hazards without people; the "hazards" arise from man's unwise, inept and careless occupation and use or abuse of geologic environment

Geologic hazards are those geologic features and events that are hazardous or harmful to the extent that they frequently result in injuries or loss of life and property. Natural geologic processes which have been going on for millions of years may become geologic hazards when people get in the way. They include such adverse geologic phe­nomena as earthquakes, volcanic eruptions, floods, landslides, sub­sidence, tsunamis, soil creep, and avalanches. If not recognized, clear­ly understood, and accounted for in the activities of man, almost any geologic processes or features can become a geologic hazard.

Throughout history, there are many examples of geologic hazards which have resulted in disaster and have greatly affected the activities of man. Volcanic eruptions, such as those of Vesuvius, Krakotoa, and Mt.Pelee are just a few examples. Ten great earthquakes in China be­tween the 11^th and 12^th centuries resulting in landslides and collapse of loessal cliffs, killed 1,5 million people. The list of disasters caused by "naturally occurring geologic hazards", or those hazards over which man has no apparent control would indeed be lengthy.

Another category of geologic hazards is that of "man-induced haz­ards". Man's activity has helped to change the rate at place of occur­rence of certain natural phenomena, resulting in hazards to himself. Some examples of man-induced hazards include: land subsidence caused by withdrawal of ground water and petroleum resulting in dam-

age to foundations and other structures, and landslides resulting from highway construction which modifies stable slopes.

Both naturally occurring and man-induced geologic hazards are merely normal geologic processes or events until man gets in the way; then these processes or events become hazards. Earthquake are haz­ards when man lives too close to the active fault area, volcanic erup-1 tions become so when man lives in close proximity to the volcano, and floods become hazards when man inhabits the flood plain.

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What can the geologist do about geologic hazards? Working with adequate knowledge he can conduct proper geologic investigations that can be used to prevent a geologic hazard from becoming a disaster. Recognition or identification of a geologic hazard at a certain locality must first be made. Once clearly identified and defined, there are several approaches to solving the problem, depending on the type of hazard. One solution is to avoid the problem by changing the proposed location of a structure such as a reservoir, nuclear power plant or highway. This solution is often necessary in the case of naturally occurring hazards. Other alternatives are to eliminate the hazard. Normally, the latter ap­proaches are more costly than avoiding the problem. The urgency to avoid or prevent geologic hazards is a necessary outgrowth of a soci­ety characterized by increasing population and urbanization.

What hope do we have for eliminating disasters caused by geologic hazards? There is little hope that they can be eliminated completely, but they could be greatly reduced with an understanding of the geolog­ic aspects of the environment. Hopefully, prediction and control of many geologic hazards will become a reality in the near future.

■ Give the Russian for:

to predict

to prevent

to reduce

to eliminate -» a hazard

to identify

to define

to recognize

to account for — to be accounted for by

to affect — to be affected by

to cause — to be caused by

to experience — to be experienced by

to result in, to result from, to get in the way, to go on, to cite, to depend on, to avoid the problem, to solve the problem, to conduct investigations, solution of the problem, to be more costly, injuries or loss of life and property, the list of disasters, withdrawal of ground water, in the case of, to the extent that..., there is little hope that..., there are several approaches

■ Give the English for:

вызывать, вызываться чем-либо, зависеть, решать проблему, избегать проблемы, существует несколько подходов к реше­нию этой проблемы, в случае..., есть небольшая надежда..., проводить исследования, продолжать, перечень, до такой сте­пени, что...

Answer the questions.

• What makes geologic features and events hazardous?

• In what way do earthquakes, volcanic eruptions, floods, land«l slides, tsunamis, subsidence affect people?

• What other examples of hazards could you provide besides those given in the text?

• What can be done to avoid, prevent or eliminate different types of hazards?