Instructor Manual Natural Hazards Earth’s Processes as Hazards, Disasters, and Catastrophes Third Edition Patricia Anderson California State University – San Marcos Chapter 1 Introduction to Natural Hazards Learning Objectives Natural processes such as volcanic eruptions, earthquakes, floods, and hurricanes become hazards when they threaten human life and property. As population continues to grow, hazards, disasters, and catastrophes become more common. An understanding of natural processes as hazards requires some basic knowledge of Earth science. Your goals in reading this chapter should be to • know the difference between a disaster and a catastrophe. • know the components and processes of the geologic cycle. • understand the scientific method. • understand the basics of risk assessment. • recognize that natural hazards that cause disasters are generally high-energy events, caused by natural Earth processes. • understand the concept that the magnitude of a hazardous event is inversely related to its frequency. • understand how natural hazards may be linked to one another and to the physical environment. • recognize that increasing human population and poor land use changes compound the effects of natural hazards, turning disasters into catastrophes. Chapter Outline 1. Introduction to Natural Hazards 1.1. Why Studying Natural Hazards Is Important 1.1.1. Processes: Internal and External 1.1.2. Hazard, Disaster, or Catastrophe 1.1.3. Death and Damage Caused by Natural Hazards 1.2. Role of History in Understanding Hazards 1.3. Geologic Cycle 1.3.1. The Tectonic Cycle 1.3.2. The Rock Cycle 1.3.3. The Hydrologic Cycle 1.3.4. Biogeochemical Cycles 1.4. Fundamental Concepts for Understanding Natural Processes as Hazards 1.4.1. Science and Natural Hazards 1.4.2. Hazards Are Natural Processes 1.4.3. Forecast, Prediction, and Warning of Hazardous Events 1.4.4. Examples of Disasters In Densely Populated Areas 1.4.5. Human Population Growth 1 © 2012 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 1.4.6. Magnitude and Frequency of Hazardous Events Case Study 1.1: Human Population through History Case Study 1.2: The Magnitude–Frequency Concept 1.4.7. Reactive Response: Impact of and Recovery from Disasters 1.4.8. Anticipatory Response: Avoiding and Adjusting to Hazards 1.5. Many Hazards Provide a Natural Service Function 1.6. Global Climate Change and Hazards Chapter Summary Natural hazards are responsible for causing significant death and damage worldwide each year. Processes that cause hazardous events include those that are internal to Earth, such as volcanic eruptions and earthquakes that result from Earth’s internal heat, and those that are external to the Earth, such as hurricanes and global warming, which are driven by energy from the sun. Natural processes may become hazards, disasters, or catastrophes when they interact with human beings. Central to an understanding of natural hazards is awareness that hazardous events result from natural processes that have been in operation for millions and possibly billions of years before humans experienced them. These processes become hazards when they threaten human life or property and should be recognized and avoided. Hazards involve repetitive events. Thus, a study of the history of these events provides much-needed information for hazard reduction. A better understanding and more accurate prediction of natural processes come by integrating historic and prehistoric information, present conditions, and recent past events, including land-use changes. Geologic conditions and materials largely govern the type, location, and intensity of natural processes. The geologic cycle creates, maintains, and destroys Earth materials by physical, chemical, and biological processes. Subcycles of the geologic cycle are the tectonic cycle, rock cycle, hydrologic cycle, and various biogeochemical cycles. The tectonic cycle describes large-scale geologic processes that deform Earth’s crust, producing landforms such as ocean basins, continents, and mountains. The rock cycle may be considered a worldwide earth-material recycling process driven by Earth’s internal heat, which melts the rocks subducted in the tectonic cycle. Driven by solar energy, the hydrologic cycle operates by way of evaporation, precipitation, surface runoff, and subsurface flow. Biogeochemical cycles can most easily be described as the transfer of chemical elements through a series of storage compartments or reservoirs, such as air or vegetation. Five fundamental concepts establish a philosophical framework for studying natural hazards. 1. Hazards are predictable from scientific evaluation. 2. Risk analysis is an important component in our understanding of the effects of hazardous processes. 2 © 2012 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. 3. Linkages exist between various natural hazards as well as between hazards and the physical environment. 4. Hazardous events that previously produced disasters are now producing catastrophes. 5. Consequences of hazards can be minimized. Answers to Review Questions: 1. What forces drive internal and external Earth processes? (p. 3) Internal forces are processes deep within the Earth, driven by plate tectonics and heat loss from Earth’s deep interior. External forces are processes that take place near the surface or at the surface of the Earth and are driven by gravity and energy from the Sun. 2. What is the distinction between a natural hazard, disaster, and catastrophe? (p. 3) A natural hazard is any natural process that poses a threat to human life or property. A disaster occurs when a hazard, such as a flood or earthquake, inflicts loss of life and property in a society. A catastrophe is a massive disaster, typically with many deaths, requiring a large input of time and money to rectify. 3. Which natural hazards are likely to be more deadly, more likely to cause property damage, and more likely to become catastrophes? (pp. 3–5) Tornados, windstorms, floods, and hurricanes are all likely to cause property damage and are more likely to become catastrophes. Earthquake, volcanic, and tsunami hazards have historically caused the greatest number of deaths, even though they occur less frequently than the weather-related catastrophes. 4. Explain why the effects of natural hazards are not constant over time. (p. 6) The effects of natural hazards change with time because of changes in land-use patterns. 5. Why is history so important in understanding natural hazards? (p. 7) Studying history provides the needed background to guide any hazard reduction plan. Specifically, history can reveal the recurrence interval for hazards such as 3 © 2012 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. floods, earthquakes, and other hazards that occur with a semi-regular frequency. 6. What kinds of information must be assembled to make hazard predictions? (p. 7) A prediction of the future occurrence and effects of a hazard requires that we combine information about historic and prehistoric behavior with a knowledge of present conditions and recent past events, including land-use changes. 7. Describe the components and interactions involved in the geologic cycle. (pp. 7–9) The Tectonic Cycle: This involves the creation, movement, and destruction of tectonic plates through geologic process driven by forces deep within Earth. Tectonic processes largely determine the quality of rocks and soils produced at plate boundaries, for which we depend on building and agriculture. Tectonics also affects the flow patterns of the oceans, which in turn influence global climate and precipitation. The Rock Cycle: The largest of the subcycles, it is linked to all the other subcycles. It depends on tectonics for heat and energy, the biogeochemical cycle for materials, and the hydrologic cycle for water. Water is then used in the process of weathering, erosion, transportation, deposition, and lithification of sediment. The Hydrologic Cycle: Driven by solar energy, this cycle moves water from the oceans to the atmosphere and back again. It operates by way of evaporation, precipitation, surface runoff, and subsurface flow, storing water in different compartments along the way. The water produced from the hydrologic cycle helps move and sort chemical elements in solution, sculpt the landscape, weather rocks, transport and deposit sediments, and provide our water resources. The Biogeochemical Cycle: This is the transfer or cycling of an element or elements through the atmosphere, lithosphere, hydrosphere, and biosphere. Chemical elements are transferred through a series of storage compartments or reservoirs, such as air, soil, groundwater, or vegetation. The biogeochemical cycle is tied to the tectonic, rock, and hydrologic cycles. 8. What are the five fundamental concepts for understanding natural processes as hazards? (pp. 9–10) The five fundamental concepts are as follows: