# Chapter 1 Study Guide: Introduction to Natural Hazards

Prepare to define the chapter's central terms, summarize each numbered section, answer every Check Your Understanding question, and apply the concepts to new natural-hazard examples.

## Chapter Learning Objectives

The chapter states these objectives. Each section below identifies the objective or objectives it supports.

- **LO:1:** Explain the difference between a disaster and a catastrophe.
- **LO:2:** Discuss the role of history in the understanding of natural hazards.
- **LO:3:** Discuss the components and processes of the geologic cycle.
- **LO:4:** Apply the scientific method to a natural hazard of your choice.
- **LO:5:** Synthesize the basics of risk assessment.
- **LO:6:** Explain how much of the damage caused by natural hazards is often related to decisions people make before, during, and after a hazardous event.
- **LO:7:** Explain why the magnitude of a hazardous event is inversely related to its frequency.
- **LO:8:** Summarize how natural hazards are linked to one another and to the physical environment.
- **LO:9:** Give reasons why increasing population and poor land-use practices compound the effects of natural hazards and can turn disasters into catastrophes.
- **LO:10:** Explain how events we view as hazards provide natural service.
- **LO:11:** Summarize links between climate change and natural hazards.

## Key Terms

- **Natural process:** A physical, chemical, or biological process that affects Earth's surface. Examples include earthquakes, volcanic eruptions, floods, landslides, and hurricanes.
- **Natural hazard:** A natural process or event that is a potential threat to human life or property. Human exposure helps turn a natural process into a hazard.
- **Disaster:** A hazardous event in a defined area and time that meets at least one criterion: 10 or more people killed, 100 or more people affected, a declared state of emergency, or a request for international assistance.
- **Catastrophe:** A massive disaster requiring significant financial expenditure and a long, often years-long, recovery.
- **Magnitude:** The size or energy released by a hazardous event.
- **Frequency:** How often an event occurs or the interval between events.
- **Risk:** The expected loss from a hazard. A simple expression is probability multiplied by consequences; a broader view considers hazard, exposure, and vulnerability.
- **Exposure:** People, property, infrastructure, resources, or other elements located in harm's way.
- **Vulnerability:** The degree of loss expected when an exposed person, structure, or system is affected.
- **Resilience:** The ability to absorb damage and recover from a hazardous event.
- **Adaptation:** An action that reduces exposure or vulnerability, such as evacuation, insurance, stronger infrastructure, or land-use planning.
- **Mitigation:** An action that reduces the effects of a hazard or disaster.
- **Geologic cycle:** The group of interacting cycles that create, maintain, alter, move, and destroy Earth's materials.
- **Uniformitarianism:** The principle that present-day processes help scientists interpret the past and anticipate comparable future processes.
- **Environmental unity:** The principle that one action can cause other effects in a chain: "you cannot do just one thing."
- **Natural service function:** A benefit provided by a natural process that can also be hazardous.
- **Wicked problem:** A complex problem with no simple solution because scientific, economic, political, cultural, and social issues interact.
- **Precursor:** A change or event that may occur before a hazardous event.
- **Forecast:** A statement giving a range or probability for what may happen.
- **Prediction:** A more specific statement about the time, place, and size of an event.
- **Warning:** Communication that danger may be imminent and that people should take protective action.

## 1.1 Why Studying Natural Hazards Is Important (LO:1, LO:8, and LO:9)

Natural processes such as earthquakes, volcanic eruptions, floods, landslides, and hurricanes become hazards when they threaten people or property. Internal Earth forces produce earthquakes and volcanoes. External forces, including solar energy and gravity, produce atmospheric, hydrologic, coastal, and slope processes. As population grows and people develop more land, exposure and vulnerability increase, making disasters and catastrophes more common.

### Internal and external processes

- **Internal processes** are driven by Earth's internal heat. Plate tectonics explains many earthquakes and volcanic eruptions.
- **External processes** operate at or near Earth's surface. Solar energy drives atmospheric circulation and the hydrologic cycle; gravity moves water and loose material downslope.
- The process itself is natural, but whether it becomes a hazard depends heavily on where and how people live.

### Hazard, disaster, or catastrophe

A natural hazard is a potential threat to life or property. A disaster is a hazardous event that occurs within a defined area and time and meets at least one standard criterion. A catastrophe is a massive disaster whose damage requires substantial resources and a long recovery. The distinction depends mainly on consequences and recovery, not simply on the physical size of the event. A large earthquake in an unpopulated area may not be a disaster, while a smaller event in a densely populated and vulnerable area may become a catastrophe.

### Death and damage

The hazards that cause the most deaths are not always those that cause the greatest property losses. In the chapter's 2015 U.S. table, floods caused the most deaths and the greatest listed economic damage. Hurricane Katrina illustrates how one catastrophe can produce enormous economic losses and years of recovery. No area is completely free of exposure to natural hazards.

### Check Your Understanding

1. **Differentiate between natural hazards, disasters, and catastrophes.**

   **Answer:** A natural hazard is a natural process or event that threatens people or property. A disaster is a hazardous event in a defined area and time that meets at least one criterion involving deaths, affected people, an emergency declaration, or international assistance. A catastrophe is a massive disaster whose human, property, or social losses require major expenditures and a long recovery.
2. **Which natural hazards in the United States take the most lives each year, and which are most costly from an economic perspective?**

   **Answer:** The chapter identifies tornadoes and windstorms as leading annual causes of deaths, although heat waves, lightning, floods, and hurricanes also kill many people. Economic losses are dominated by large, costly events involving floods, hurricanes, earthquakes, and other catastrophes. Hurricane Katrina is identified as the most costly U.S. catastrophe in the chapter, while floods had the greatest listed deaths and damages in the 2015 weather-related table.
3. **Which hazards have taken the most lives worldwide and in the United States in the past two decades?**

   **Answer:** Worldwide from 1996 to 2015, earthquakes and tsunamis accounted for the largest share of deaths, about 57 percent. Storms accounted for about 18 percent, extreme temperatures 12 percent, and floods 11 percent. For the United States, the chapter identifies tornadoes and windstorms as major annual killers and provides a 2015 table in which floods caused the most deaths; it does not give one equivalent two-decade U.S. percentage.
4. **How and why are land-use change and global warming influencing natural hazards?**

   **Answer:** Urbanization places more people and property on floodplains, steep slopes, and coasts. Paving increases runoff, altered drainage changes flooding, and vegetation removal increases erosion and landslides. Warming oceans add energy to storms, sea-level rise increases coastal flooding and erosion, and climate change makes drought more common and severe in arid and semiarid regions. Overall damage can increase even while deaths from some hazards decline because forecasting, warnings, preparedness, and sanitation improve.

## 1.2 The Role of History in Understanding Hazards (LO:2)

Natural hazards are repetitive events, so their history is essential for hazard assessment and reduction. Scientists combine written records and recent human history with prehistoric geologic evidence. Maps, aerial photographs, landforms, fault features, flood deposits, landslide deposits, tsunami deposits, and radiocarbon-dated wood or shells can extend the record beyond the period of written observations.

Historical and geologic records help scientists determine where hazards occurred, how large they were, how frequently they happened, what evidence they left, and what may happen in the future. A short period without an event does not prove that an area is safe. **Uniformitarianism** uses present-day processes to interpret past evidence and anticipate comparable future events.

### Check Your Understanding

1. **Why is recent geologic history as well as human history important in the study of natural hazards?**

   **Answer:** Natural hazards repeat, but written human records are usually short. Recent geologic history preserves evidence of older events in deposits, landforms, faults, cracks, and other features. Combining prehistoric evidence with historical records reveals the location, size, frequency, and effects of past events, which improves estimates of future hazards and supports land-use planning and warnings.

## 1.3 The Geologic Cycle (LO:3)

The geologic cycle is the set of interacting physical, chemical, and biological processes that create, maintain, change, move, and destroy Earth's materials. Its four major subcycles are the tectonic cycle, rock cycle, hydrologic cycle, and biogeochemical cycles. Geologic conditions and materials help determine the type, location, and intensity of natural processes.

### Tectonic cycle

The tectonic cycle involves the creation, movement, and destruction of tectonic plates. Tectonic processes deform Earth's crust and produce ocean basins, continents, mountains, earthquakes, and volcanoes. They are driven by forces deep within Earth.

### Rock cycle

The rock cycle is a worldwide recycling system driven by Earth's internal heat and linked to the tectonic, hydrologic, and biogeochemical cycles:

- **Igneous rock** forms when molten rock crystallizes.
- **Sedimentary rock** forms when weathered material is transported, deposited, compacted, and cemented, or lithified.
- **Metamorphic rock** forms when existing rock is changed by heat, pressure, deep burial, or chemically active fluids without melting.

Uplift exposes rocks to weathering and erosion. Sediment is transported by wind, water, ice, and gravity, then deposited and lithified. Burial can cause metamorphism, and deeper burial can cause melting. Rock type affects hazards: limestone can dissolve and form sinkholes, while shale is commonly associated with landslides.

### Hydrologic cycle

Solar energy drives water through evaporation, precipitation, surface runoff, and subsurface flow. Water is stored in oceans, the atmosphere, rivers, groundwater, lakes, ice caps, and glaciers. Near-surface water weathers rock, transports and deposits sediment, sculpts the landscape, supplies ecosystems and people, and links to flooding, landslides, subsidence, volcanoes, storms, coastal erosion, and climate change.

### Biogeochemical cycles

Biogeochemical cycles transfer chemical elements among the atmosphere, lithosphere, hydrosphere, and biosphere. Carbon, nitrogen, and phosphorus are important examples. The carbon cycle is especially relevant because carbon dioxide is associated with global warming and changes in climate-related hazards.

### Check Your Understanding

1. **Define the geologic cycle and describe its subcycles.**

   **Answer:** The geologic cycle is the group of interacting processes that create, maintain, alter, move, and destroy Earth's materials. Its major subcycles are the tectonic cycle, which creates and recycles tectonic plates and builds landforms; the rock cycle, which forms and transforms igneous, sedimentary, and metamorphic rocks; the hydrologic cycle, which moves and stores water through evaporation, precipitation, runoff, and subsurface flow; and biogeochemical cycles, which move chemical elements among air, rock, water, soil, and living organisms.
2. **Why is the geologic cycle pertinent to understanding natural hazards?**

   **Answer:** The cycles produce and modify the rocks, landforms, water, atmosphere, and ecosystems that control where hazards occur and how intense they are. Plate movement creates earthquakes and volcanoes, rock properties influence landslides and sinkholes, water drives flooding and erosion, and carbon cycling affects climate-related hazards. Understanding these linked processes helps explain both the natural event and its effects on people.

## 1.4 Fundamental Concepts for Understanding Natural Processes as Hazards (LO:4 through LO:9)

The chapter presents five concepts as a framework for studying natural hazards:

1. **Hazards are predictable from scientific evaluation.** Science can identify locations, probabilities, magnitudes, frequencies, and possible precursors, although exact prediction is not always possible.
2. **Risk analysis is important.** Decisions should consider probability, consequences, exposure, vulnerability, resilience, adaptation, and mitigation.
3. **Linkages exist between hazards and the physical environment.** One hazard can trigger another, and changes to land, water, vegetation, or climate can alter hazard effects.
4. **Human actions can turn disasters into catastrophes.** Population growth, poor construction, poverty, deforestation, and development in hazardous places increase exposure and vulnerability.
5. **Consequences can be minimized.** Scientific understanding, land-use planning, regulation, engineering, warnings, preparedness, and recovery decisions reduce losses.

### Science and the scientific method

The scientific method begins with a question, uses observations and evidence, proposes a testable hypothesis, tests that hypothesis, and rejects, revises, or provisionally retains it based on the results. Scientists try to disprove hypotheses rather than treat them as unquestionable facts.

**Example application:** To investigate a landslide, ask whether a broken buried water main caused it. Observe water emerging from the slope and formulate the hypothesis that the leak saturated the slope, reduced the strength of its materials, and caused failure. Inspect or excavate the slope and water line, measure the relevant conditions, and compare alternative explanations. If no leak is found, reject or revise the hypothesis.

### Forecasting, prediction, and warning

- **Location:** Where a hazardous event is likely to occur, often shown on a hazard map.
- **Probability:** The chance that an event of a given magnitude will occur at a place during a specified time.
- **Precursor:** A change that may occur before an event, such as landslide creep, earthquake activity, volcanic swelling, or gas emissions.
- **Forecast:** A statement with a range or probability, such as a 40 percent chance of severe storms.
- **Prediction:** A more specific statement about the time, place, and size of an event.
- **Warning:** Communication that danger may be imminent and that protective action should be taken.

Scientists can often forecast where and how frequently hazards occur, but accurate short-term predictions remain difficult for hazards such as earthquakes and volcanic eruptions. Warnings can still be useful even when a forecast is uncertain.

### Risk assessment and management

Risk may be expressed as:

`Risk = probability x consequences`

A broader framework treats risk as dependent on hazard, exposure, and vulnerability. A large event has lower probability but greater possible consequences; a smaller event in a crowded, vulnerable city may pose greater risk than the same event in a sparsely populated area with resistant construction. Risk assessment identifies the hazard and location, estimates probabilities for possible magnitudes, identifies exposed and vulnerable elements, estimates consequences, and compares scenarios. Short records, uncertain probabilities, complex consequences, and incomplete knowledge limit the analysis, but do not make it useless.

Risk management includes hazard assessment, mitigation, emergency response, recovery planning, engineering, land-use regulation, education, insurance, and public communication. Some hazard problems are **wicked problems** because science alone cannot resolve the political, economic, cultural, and social issues involved.

### Environmental unity and linked hazards

Environmental unity means that one action can lead to a chain of other effects. Removing vegetation from a steep slope may trigger a landslide; the slide may dam a stream; the resulting lake may overtop or fail; and a flood or debris flow may damage communities downstream. Earthquakes can trigger landslides and tsunamis, hurricanes can cause flooding and coastal erosion, and floods can contaminate water and produce disease.

### Population, land use, and human decisions

Population growth increases the number of people and amount of property exposed to hazards. Urbanization can place people on marginal land and alter drainage, slope angles, vegetation, erosion, and sedimentation. Poor construction and inadequate infrastructure increase vulnerability. Decisions made before, during, and after an event can greatly increase or decrease total losses.

### Magnitude and frequency

In general, small events occur frequently and large events occur rarely. A greater energy release or unusual set of conditions is less common, so frequency generally decreases as magnitude increases. Moderate events may do the most cumulative landscape work because they occur often enough to have repeated effects. Exceptions occur: rare intense floods may move most sediment in arid regions, and large storms may do most of the work along barrier-island coasts.

### A + B = C and response

- **A:** Direct losses caused by the natural event.
- **B:** Additional losses related to human decisions and systems before, during, and after the event.
- **C:** Total losses, so `A + B = C`.

Poor engineering, weak building codes, inadequate maintenance, failure to prepare, delayed warnings, poor emergency response, and rebuilding in unsafe locations can make B very large. The chapter's Robert Bea profile gives an illustrative estimate that direct losses may be about 20 percent of financial losses in some disasters; this is not a universal percentage.

**Reactionary or reactive response** occurs after an event and includes search and rescue, firefighting, emergency shelter, restoration, and reconstruction. **Anticipatory response** occurs before an event and includes hazard mapping, land-use planning, resistant construction, evacuation planning, education, drills, and infrastructure maintenance. Recovery can reduce future risk or recreate it.

### Check Your Understanding

 1. **Describe the five fundamental concepts.**

    **Answer:** The five concepts are that hazards are predictable from scientific evaluation; risk analysis is important; hazards are linked to one another and to the physical environment; human actions can turn disasters into catastrophes; and the consequences of hazards can be minimized through science, planning, engineering, warnings, preparedness, and appropriate recovery.
 2. **How is risk from natural hazards evaluated?**

    **Answer:** A simple risk estimate multiplies the probability of an event by its consequences. A broader assessment considers the hazard, exposure, and vulnerability. Scientists identify the location and possible magnitudes, estimate probabilities from historical and geologic evidence, identify people and property at risk, estimate likely losses, compare scenarios, and use the results for management decisions.
 3. **What is uniformitarianism, and how does it help us understand natural hazards?**

    **Answer:** Uniformitarianism is the principle that present-day processes help explain the past. By studying how floods, landslides, earthquakes, and other processes operate today, scientists can interpret deposits and landforms from older events and anticipate where and how similar events may occur in the future. It does not mean that every event repeats at exactly the same size or interval.
 4. **Differentiate among precursor events, forecasting, predictions, and warnings.**

    **Answer:** A precursor is a change that may occur before an event, such as creep, foreshocks, volcanic swelling, or gas emissions. A forecast gives a range or probability of what may happen. A prediction is more specific about the time, place, and size of an event. A warning communicates that danger may be imminent and tells people to take protective action.
 5. **Explain what is meant by the magnitude-frequency concept.**

    **Answer:** The magnitude-frequency concept states that, in general, the larger the event, the less frequently it occurs. Small events require less energy and are common; large events require greater energy or unusual conditions and are rare. The relationship is general rather than absolute, and the effects of moderate or rare events depend on the environment and human exposure.
 6. **Why are population growth and land use important in understanding consequences of natural hazards?**

    **Answer:** Population growth places more people and property in harm's way and often pushes development onto floodplains, steep slopes, and coasts. Urbanization changes runoff, drainage, slope geometry, vegetation, and sediment movement. Poor construction, poverty, and inadequate infrastructure increase vulnerability, so similar natural events can produce very different losses.
 7. **Differentiate between reactionary responses and anticipatory responses.**

    **Answer:** Reactionary responses occur after a hazardous event and include rescue, firefighting, emergency shelter, service restoration, and reconstruction. Anticipatory responses occur before an event and include avoiding hazardous locations, enforcing building standards, mapping hazards, planning evacuations, educating the public, conducting drills, and maintaining infrastructure. Anticipatory actions usually reduce long-term risk more effectively.
 8. **When we say consequences of hazards are as simple as A + B = C, what do we mean?**

    **Answer:** A is the direct loss caused by the natural event, B is the additional loss caused by human decisions and systems before, during, and after the event, and C is the total loss. Poor construction, inadequate planning, delayed response, and unsafe rebuilding can make B much larger than it needed to be.
 9. **Explain Robert Bea's message in his Professional Profile.**

    **Answer:** Bea argues that catastrophes are not caused only by the natural event or by engineering failure. Human and organizational decisions, inadequate science, neglected maintenance, weak safety systems, poor planning, and failure to prepare can greatly increase losses. Better planning, engineering, institutions, warnings, and willingness to spend money before an event can save much more later.
10. **Define what is meant by a wicked problem.**

**Answer:** A wicked problem is a complex problem resistant to a simple solution because scientific, political, economic, cultural, and social issues interact. Natural-hazard management can become wicked when competing interests make it difficult to agree on land use, protection, relocation, funding, or acceptable risk. Progress requires more than science alone.

## 1.5 Many Hazards Provide a Natural Service Function (LO:10)

The same natural processes that kill people or damage property can provide benefits. Floods deposit fertile sediment, transport nutrients, deliver sediment to beaches, and flush pollutants from estuaries. Landslides can create stable debris dams and lakes that provide water storage and aesthetic value. Volcanic eruptions create new land and fertile soils. Earthquakes build mountains, create groundwater barriers and springs through fault gouge, and form structures that trap petroleum and natural gas.

These benefits do not eliminate the hazard. A stable landslide dam can later fail, fertile volcanic soil can encourage settlement near a volcano, and floodplain benefits can encourage people to build in a flood-prone area.

### Check Your Understanding

1. **What is meant by the phrase natural service functions?**

   **Answer:** Natural service functions are benefits supplied by natural processes that may also be hazardous. The benefits may support water resources, fertile soils, ecosystems, minerals, energy, landscapes, or other needs.
2. **List some examples of natural service functions of floods, earthquakes, landslides, and volcanic eruptions.**

   **Answer:** Floods supply fertile floodplain sediment and nutrients, deliver sediment to beaches, and flush pollutants from estuaries. Earthquakes build mountains, create groundwater springs and barriers through fault gouge, and form petroleum and natural-gas traps. Landslides can create stable lakes that provide water storage and an aesthetic resource, although unstable dams may fail and cause flooding. Volcanic eruptions create new land and fertile soils.

## 1.6 Global Climate Change and Hazards (LO:11)

The chapter links human-caused climate change, especially fossil-fuel use, to changing natural hazards. Warmer oceans add energy to the atmosphere and can increase the intensity of storms and hurricanes. Thermal expansion of seawater and melting glacial ice raise sea level, increasing coastal flooding and erosion. Changing precipitation can increase flooding in some regions and drought in others. Deserts and semiarid regions may expand, food-production areas may shift, and migration or social and political disruption may follow.

Climate change may also affect wildfire, landslides, and other weather-driven hazards. The chapter presents these relationships as likely effects that can vary by region, not as identical changes for every hazard everywhere.

### Check Your Understanding

1. **In what ways might global climate change influence the occurrence of natural hazards such as coastal erosion, extreme weather events, and droughts?**

   **Answer:** Warming seawater expands and melting ice adds water to the oceans, raising sea level and increasing coastal flooding and erosion. Warmer oceans feed more energy into the atmosphere, which can increase the severity and frequency of some hazardous weather, such as thunderstorms and tornadoes, and increase hurricane intensity. Changes in precipitation and expanding deserts and semiarid regions can make droughts more common and severe, while altered storms and vegetation can change wildfire, landslide, and erosion patterns.

## Important Case Studies and Examples (supports LO:1 through LO:11)

- **2010 Haiti earthquake:** A magnitude 7.0 earthquake caused catastrophic losses because of high population density, poverty, poorly constructed buildings, inadequate infrastructure, poor sanitation, deforestation, erosion, and exposure to landslides and flooding. The event illustrates how human vulnerability can dominate total losses.
- **1989 Loma Prieta earthquake:** A similarly sized earthquake caused far fewer deaths because construction, infrastructure, exposure, and preparedness were different. The comparison shows that magnitude alone does not determine consequences.
- **Hurricane Katrina, 2005:** Flooding in New Orleans and damage along the Mississippi coast produced a U.S. catastrophe requiring extensive, long-term recovery.
- **Mexico City:** Dense population, soft ancient lake sediments, and groundwater pumping compounded earthquake shaking, subsidence, and vulnerability.
- **Rapid City, South Dakota:** Careful post-flood planning converted floodplain land into a greenbelt and reduced future flood risk.
- **Anchorage, Alaska:** Rapid reconstruction after the 1964 earthquake, without adequate land-use planning, recreated vulnerability on ground that had ruptured before.
- **Robert Bea:** The professional profile emphasizes that human decisions and organizational systems before, during, and after an event can greatly increase or reduce losses.
- **2015 U.S. weather-related disasters:** Floods caused the most deaths and the greatest listed economic damage in the chapter's table.

## Likely Comparison Questions

Be ready to answer these directly:

- How do a natural process, natural hazard, disaster, and catastrophe differ?
- How do internal and external processes differ?
- Why do human and geologic history both matter for hazard assessment?
- How does uniformitarianism connect past, present, and future hazards?
- What are the four subcycles of the geologic cycle?
- How do the tectonic, rock, hydrologic, and biogeochemical cycles connect to hazards?
- How do the three rock types form and change?
- How do location, probability, precursor, forecast, prediction, and warning differ?
- How is risk evaluated using probability, consequences, exposure, and vulnerability?
- How does environmental unity produce cascading hazards?
- Why are magnitude and frequency generally inversely related?
- How do population growth, land use, and construction affect hazard consequences?
- How do A + B = C, reactionary response, and anticipatory response describe losses and recovery?
- How do hazards provide natural service functions?
- How can climate change alter storms, flooding, coastal erosion, drought, wildfire, and landslides?

## Practice Questions

 1. Distinguish among a natural process, natural hazard, disaster, and catastrophe.
 2. Explain why two earthquakes of similar magnitude can produce very different death tolls.
 3. Explain how recent geologic history extends the record of hazardous events.
 4. Define the geologic cycle and describe its four major subcycles.
 5. Trace one possible pathway through the rock cycle.
 6. Explain how the hydrologic cycle connects to flooding, landslides, storms, and climate.
 7. Apply the scientific method to a hypothesis about a landslide, flood, earthquake, or volcanic eruption.
 8. Differentiate location, probability, precursor, forecast, prediction, and warning.
 9. Explain risk using both the probability-consequence and hazard-exposure-vulnerability frameworks.
10. Give an example of environmental unity and trace the resulting chain of hazards.
11. Explain the magnitude-frequency concept and give one exception or qualification.
12. Explain how population growth and land-use practices increase exposure and vulnerability.
13. Explain A + B = C using examples of decisions made before, during, and after an event.
14. Contrast reactionary and anticipatory responses.
15. Define a wicked problem and explain why science alone may not solve it.
16. Give one natural service function for floods, landslides, earthquakes, and volcanic eruptions.
17. Explain two ways climate change may alter natural hazards.
18. Use Haiti and Loma Prieta to explain why human conditions matter as much as event magnitude.
19. Compare Rapid City and Anchorage as examples of post-disaster land-use decisions.
20. Explain why risk assessment remains useful even when historical records and probabilities are incomplete.

## Quick Review Checklist

Before the quiz or test, make sure you can:

- define every bold term without looking;
- distinguish a natural process, hazard, disaster, and catastrophe;
- summarize each section from 1.1 through 1.6;
- explain why historical and prehistoric evidence matter;
- name and explain the four geologic-cycle subcycles;
- trace a pathway through the rock cycle;
- state and explain the five fundamental concepts;
- apply the scientific method to a natural hazard;
- distinguish a forecast from a prediction and a warning;
- calculate or explain the basic idea of risk;
- explain exposure, vulnerability, resilience, adaptation, and mitigation;
- trace a cascade of linked hazards;
- explain how human choices affect losses;
- explain the magnitude-frequency relationship;
- list natural service functions; and
- connect climate change to at least three natural hazards.