Natural Hazards Vocabulary

Earthquake in Haiti, 2010: A Human-Caused Catastrophe?

Haiti's Vulnerability:
- Recognized as an environmental catastrophe waiting to happen.
- Population increase and deforestation (~90% of the mountainous country) exacerbate risks.
- Vulnerable to hurricanes, storms, runoff flooding, and landslides.
- Prone to large earthquakes (three major ones since 1750).

The 2010 Earthquake in Haiti

Killed over 200,000 Haitians and injured over 300,000.
Magnitude 7.0.
Disproportionate loss of life compared to the Loma Prieta earthquake (magnitude 7.1 in San Francisco, 1989, caused 63 deaths).

Socio-Economic Factors in Haiti

Poorest country in the Western Hemisphere.
Low annual income per person.
Impacted by four tropical storms and hurricanes within a month in 2008, causing landslides and ~800 deaths.
Harvest of food crops destroyed, resulting in a grim situation.

Natural Hazards vs. Human Impact

Natural processes (volcanic eruptions, earthquakes, floods, hurricanes) become hazards when they threaten human life and property.
Population growth increases hazards, disasters, and catastrophes.
Understanding natural processes requires basic earth science knowledge.

Learning Objectives

Differentiate between a disaster and a catastrophe.
Discuss the role of history in understanding natural hazards.
Discuss the components and processes of the geologic cycle.
Apply the scientific method to a natural hazard.
Synthesize the basics of risk assessment.
Explain how damage is related to decisions people make.
Explain the inverse relationship between magnitude and frequency.
Summarize how natural hazards are linked.
Give reasons why to increase population.
Explain how events we view as hazards provide a natural service.
Summarize links between climate change and natural hazards.

Deforestation in Haiti

Trees removed for cooking fuel, leading to soil erosion, farmland damage, and vulnerability to landslides and floods.
Reforestation efforts in the 1980s failed due to trees being cut down.

Conditions in Port-au-Prince Before the Earthquake

~85% of people lived in slums in concrete buildings unable to withstand earthquake shaking.
Poor sanitation: half without toilets, ~30% with access to clean water.
Earthquake destroyed/damaged ~190,000 homes, killing nearly a quarter of a million and leaving over 2 million homeless.
~1.5 million people lived in camps post-earthquake.
City covered in 19 million cubic meters (25 million cubic yards) of rubble.
Humanitarian disaster with untreated injuries, little food, and infectious diseases (cholera caused ~6,000 deaths).

Building Construction Issues

Buildings not designed to withstand earthquakes.
Problems: heavy, unsupported block walls, lack of rebars, poorly compacted concrete, substandard materials (marine sands).

Human Footprint in the Catastrophe

Improper building construction led to significant loss of life.
Rapid population growth and collapsed schools contributed to the high death toll.

Post-Earthquake and Hurricane Matthew

Haiti has not recovered since the earthquake.
In October 2016, Hurricane Matthew killed ~1,000 people and caused extensive destruction.
Mass graves were needed, and a cholera outbreak occurred from contaminated water.
The earthquake set the stage for further damage due to poorly constructed shelters, deforestation, and crop destruction.
A cascade of declining conditions resulted.

Rebuilding and Hazard Preparation

Need for cost-effective, earthquake-resistant structures.
Consequences of another earthquake or hurricane are dire.
Haiti must be assisted in hazard preparation.

Importance of Studying Natural Hazards

Recent global events: tsunamis (Indian Ocean, Japan), floods (Pakistan, Venezuela, Bangladesh, Thailand, Europe), volcanic eruption, and earthquakes.
North American events: hurricanes (Gulf Coast, Atlantic Coast, Guatemala, Honduras), wildfires (western Canada, Arizona, Colorado, Utah, California, Kansas, Texas), tornadoes, ice storm (New England, Quebec), hail (Nebraska), and rapid climate warming.
Forces at work inside and on the surface of the planet need understanding.

Processes: Internal and External

Process: physical, chemical, and biological ways events affect Earth's surface.
Internal forces: volcanic eruptions and earthquakes (explained by plate tectonics).
External forces: energy from the sun warms Earth, producing winds and evaporating water (hydrologic cycle).
External processes: Landsliding results from gravity acting on hillslopes and mountains.
Energy released varies greatly. Example:
- Average tornado expends about $1,000$ times as much energy as a lightning bolt.
- Volcanic eruption of Mount St. Helens in May 1980 expended approximately a million times as much energy as a lightning bolt.
- Solar energy Earth receives each day is about a trillion times that of a lightning bolt.

Hazard, Disaster, or Catastrophe

Natural Hazard: a natural process and event that is a potential threat to human life and property.
Disaster: a hazardous event that occurs over a limited time span within a defined area with one of the following criteria met:
- (1) 10 or more people are killed,
- (2) 100 or more people are affected,
- (3) a state of emergency is declared,
- (4) international assistance is requested.
- Catastrophe: a massive disaster that requires significant expenditure of money and a long time (often years) for recovery.
Hurricane Katrina (2005) was the most damaging and costly catastrophe in U.S. history.

Risk Assessment

Natural hazards affect millions, and all U.S. areas are at risk.
No area is hazard-free.
From 1996 to 2015, natural disasters killed ~1.3 million worldwide (~65,000/year): earthquakes and tsunamis (57%), storms (18%), extreme temperature(12%), and floods (11%).
Financial loss exceeds $50 billion$ /year (excluding social losses).
1970 Bangladesh hurricane and 1976 China earthquake each claimed over 300,000 lives.
2004 Indian Ocean tsunami: ~230,000 deaths.
1991 Bangladesh hurricane: 145,000 lives claimed.
2005 Hurricane Katrina: ~1,600 deaths, $250 billion$ in damages.
2005 Pakistan earthquake: >80,000 lives lost.
Hurricanes caused by atmospheric disturbance, and earthquakes caused by Earth's internal heat driving tectonic plates.
Impact of events is connected to human population density and land-use patterns.

Increase in Catastrophes and Disasters

Significant increase in catastrophes and disasters worldwide in recent decades (1980-2015).
Flooding and storms caused ~61% of disasters and affected ~56% of people.
Earthquakes caused ~57% of deaths.
Medium- to low-income countries suffered most from floods/storms.
High-income countries suffered the greatest economic losses but the lowest number of deaths.
Economic losses have increased faster than the number of deaths due to warning systems, disaster preparedness, and sanitation improvement.
In 2015, 44% of disasters occurred in Asia (4.44 billion people), while the U.S. (0.33 billion people) experienced ~6% of the disasters.

Death and Damage by Natural Hazards

Greatest loss of life: tornadoes and windstorms, heat waves, lightning, floods, and hurricanes.
1994 Northridge earthquake: ~60 deaths, at least $20 billion$ in property damage.
The next great earthquake in a densely populated part of California could inflict $100 billion$ in damages while killing several thousand people.
Natural disasters cost the U.S. multibillion dollars annually; the average cost of a single major disaster may exceed $500 million$ . Cost in 2014 was $25 billion$ .
About 200 weather-related disasters and catastrophes occurred in the U.S. since 1980, totaling approximately $1.1 trillion$ (an average of approximately $33 million$ per year).
Hurricane Katrina cost approximately $250 billion$ (damages and other economic losses).

Evaluating Hazards

An important aspect of all natural hazards is their potential to produce a catastrophe, which has been defined as any situation in which the damages to people, property, or society in general are sufficient that recovery and/or rehabilitation is a long, involved process.
Natural hazards vary greatly in their potential to cause a catastrophe.
Floods, hurricanes, tornadoes, earthquakes, volcanic eruptions, large wildfires, and heat waves are the hazards most likely to have a high potential to create catastrophes.
Landslides generally affect a smaller area and have only a moderate potential to produce a catastrophe.
Drought also has a moderate potential to produce a catastrophe because, although drought may cover a wide area, there is usually plenty of warning time before its worst effects are felt.
Hazards with a low potential to produce a catastrophe include coastal erosion, frost, lightning, and expansive soils.
Effects of natural hazards change due to changes in human land use and climate change.
Urban growth can influence people to develop on marginal lands, such as steep hillsides and floodplains.
In addition to increasing population density, urbanization can also change the physical properties of earth materials by influencing drainage, altering the steepness of hillslopes, and removing vegetation.
Climate change in the United States and the world is affecting natural hazards.
As the world warms, warming oceans feed more energy into storms, causing an increase in storm intensity.
Rising sea levels and larger waves from more intense storms associated with global warming are flooding land and increasing coastal erosion.
Climate change is also causing drought to become more common and more extreme in the arid and semiarid regions of Earth.
Overall, damage from most natural hazards in the United States is increasing, but the number of deaths from many hazards is decreasing because of better prediction, forecasting, and warning.

Check Your Understanding

Differentiate between natural hazards, disasters, and catastrophes.
Which natural hazards in the United States take the most lives each year, and which are the most costly from an economic perspective?
Which hazards have taken the most lives worldwide and in the United States in the past two decades?
How and why are land-use change and global warming influencing natural hazards?

The Role of History in Understanding Hazards

A fundamental principle for understanding natural hazards is that they are repetitive events, and, therefore, the study of their history provides much-needed information for any hazard reduction plan.
Whether we are studying earthquakes, floods, landslides, or volcanic eruptions, knowledge of historic events and the recent geologic history of an area is vital to our understanding and assessment of the hazard.
Before we can truly appreciate the nature and extent of a natural hazard, we must study in detail its historic occurrence, as well as any geologic features that it may produce or affect.
Any prediction of the future occurrence and effects of a hazard will be more accurate if we can combine information about historic and prehistoric behavior with a knowledge of present conditions and recent past events, including land-use changes.
To fully understand the natural processes we call hazards, some background knowledge of the geologic cycle processes that produce and modify earth materials, such as rocks, minerals, and water, is necessary.
Linking the prehistoric and historic records extends our perspective of time when we study repetitive natural events.

Check Your Understanding

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

The Geologic Cycle

Geologic conditions and materials largely govern the type, location, and intensity of natural processes.
Earthquakes and volcanoes do not occur at random across Earth's surface; rather, most of them mark the boundaries of tectonic plates.
Understanding the components and dynamics of the geologic cycle will explain these relationships.
Throughout much of the 4.6 billion years of Earth's history, the materials on or near Earth's surface have been created, maintained, and destroyed by numerous physical, chemical, and biological processes.
Continuously operating processes produce the earth materials, land, water, and atmosphere necessary for our survival.
Collectively, these processes are referred to as the geologic cycle, which is really a group of subcycles that includes:
- the tectonic cycle
- the rock cycle
- the hydrologic cycle
- biogeochemical cycles.

The Tectonic Cycle

The term tectonic refers to the large-scale geologic processes that deform Earth's crust and produce landforms such as ocean basins, continents, and mountains.
Tectonic processes are driven by forces deep within Earth.
The tectonic cycle involves the creation, movement, and destruction of tectonic plates.
It is responsible for the production and distribution of rock and mineral resources invaluable to modern civilization, as well as hazards such as volcanoes and earthquakes.

The Rock Cycle

Rocks are aggregates of one or more minerals.
A mineral is a naturally occurring, crystalline substance with defined properties
The rock cycle is the largest of the geologic subcycles, and it is linked to all the other subcycles. It depends on the tectonic cycle for heat and energy, the biogeochemical cycle for materials, and the hydrologic cycle for water.
Water is then used in the processes of weathering, erosion, transportation, deposition, and lithification of sediment.
Types of rocks:
- Igneous
- Sedimentary
- Metamorphic
Rocks are classified into three general types, or families, according to how they were formed in the rock cycle.
We may think of the rock cycle as a worldwide rock recycling process driven by Earth's internal heat, which melts the rocks subducted in the tectonic cycle. Crystallization of molten rock produces igneous rocks beneath and on Earth's surface. Rocks at or near the surface break down chemically and physically by weathering to form particles known as sediment. These particles vary in size from fine clay to very large pieces of boulder-sized gravel. Sediment formed by weathering is then transported by wind, water, ice, and gravity to depositional basins, such as the ocean. When wind or water currents slow down, ice melts, or when material moving downward due to gravity reaches a flat surface, the sediment settles and accumulates by a process known as deposition. The accumulated layers of sediment eventually undergo lithification (conversion to solid rock), forming sedimentary rocks. Lithification takes place by cementation and compaction as sediment is buried beneath other sediment. With deep burial, sedimentary rocks may be metamorphosed (altered in form) by heat, pressure, or chemically active fluids to produce metamorphic rocks. Metamorphic rocks may be buried to depths where pressure and temperature conditions cause them to melt, beginning the entire rock cycle again. As with any other Earth cycle, there are many exceptions or variations from the idealized sequence. For example, an igneous or metamorphic rock may be altered into a new metamorphic rock without undergoing weathering or erosion, or sedimentary and metamorphic rocks may be uplifted and weathered before they can continue on to the next stage in the cycle. Finally, there are other sources of sediment that have a biological or chemical origin and types of metamorphism that do not involve deep burial. Overall, the type of rock formed in the rock cycle depends on the rock's environment.
The rock cycle has many links to natural hazards.
Different rock types have different composition, and the different composition is often linked to specific processes.

The Hydrologic Cycle

The movement of water from the oceans to the atmosphere and back again is called the hydrologic cycle.
Driven by solar energy, the cycle operates by way of evaporation, precipitation, surface runoff, and subsurface flow, and water is stored in different compartments along the way.
These compartments include the oceans, atmosphere, rivers and streams, groundwater, lakes, and ice caps and glaciers.
The residence time, or estimated average amount of time that a drop of water spends in any one compartment, ranges from tens of thousands of years or more in glaciers to nine days in the atmosphere.
Only a very small amount of the total water in the cycle is active near Earth's surface at any one time.
Surface runoff is the primary factor in river flooding
Groundwater is one of the most important factors in landslides and subsidence
Water is important in volcanic processes
Water injected with other materials is an important factor in human-induced earthquakes
Water in motion in the oceans and atmosphere is an important factor in coastal erosion and violent storms
Water vapor is an important factor in atmospheric processes that produce storms. As a result, it is a significant factor in climate change and changes in hazardous events.

BIOGEOCHEMICAL CYCLES

A biogeochemical cycle is the transfer or cycling of a chemical element or elements through the atmosphere (the layer of gases surrounding Earth), lithosphere (Earth's rocky outer layer), hydrosphere (oceans, lakes, rivers, and groundwater), and biosphere (the part of the Earth where life exists).
Tectonic cycle provides water, heat, and energy.
Rock and hydrologic cycles transfer and store chemical elements.
Well understood biogeochemical cycle means knowing the rate of transfer among all compartments
The carbon cycle (CO2) is of particular importance to hazards as it is associated with global warming, which is changing climate and the nature and intensity of weather-driven processes, such as intense storms.

Check your understanding

Define the geologic cycle and describe its subcycles.
Why is the geologic cycle pertinent to understanding natural hazards?

Fundamental Concepts for Understanding Natural Processes as Hazards

The five concepts described next are basic to an understanding of natural hazards.
These fundamental concepts serve as a conceptual framework for our discussion of each natural hazard in subsequent chapters of this book.
Most chapters begin and end with a case study that evaluates a natural hazard with respect to each of the five fundamental concepts described below.

Science helps us predict hazards.

Science is a body of knowledge that has accumulated from investigations and experiments, the results of which are subject to verification.
The method of science, often referred to as the scientific method, has a series of steps. The first step is the formulation of a question. With respect to a hazardous event, geologists may ask: Why did a landslide occur that destroyed three homes?

Hazards are natural processes

Learning to adjust to harsh and changing climatic conditions has been necessary for our survival from the very beginning.
Its has been recently suggested that we may be in a new epoch known as the Anthropocene epoch.
Events we call natural hazards are natural Earth processes. They become hazardous when people live or work near these processes and when land-use changes such as urbanization or deforestation amplify their effect
The best approach to hazard reduction is to identify hazardous processes and delineate the geographic areas where they occur.

Forecast, Prediction, and Warning of Hazardous Events

The idea that "the present is the key to the past," called uniformitarianism, was popularized in 1785 by James Hutton (referred to by some scholars as the father of geology) and is heralded today as a fundamental concept of Earth sciences. Therefore, to predict the long-range effects of flooding, we must be able to determine how future human activities will change the size and frequency of floods. In this case, the present is the key to the future. -The principle of environmental unity states that one action causes others in a chain of actions and events.
A prediction of a hazardous event such as an earthquake involves specifying the date, time, and size of the event. This is different from predicting where or how often a particular event such as a flood will occur. A forecast, on the other hand, has ranges of certainty.
Attempting to do this involves most or all of the following elements:
- Identifying the location where a hazardous event is likely to occur
- Determining the probability that an event of a given magnitude will occur
- Observing any precursor events
- Forecasting or predicting the event
- Warning the public.

Knowing hazard risks can help people make decisions.

Before rational people can discuss and consider adjustments to hazards, they must have a good idea of the risk that they face in various circumstances. The field of risk assessment is rapidly growing, and its application in the analysis of natural hazards probably should be expanded.
The risk of a particular event may be simply defined as the product of the probability of that event occurring multiplied by the consequences should it occur."
Consequences (damages to people, property, economic activity, public service, and so on) can be expressed on a variety of scales. Thinking deeper about risk (Figure 1.11), we have come to realize that the hazard and the probability of occurrence of hazards includes both the natural process (earthquake, flood, etc.) and the human processes that can change the probability. For example, urbanization can change the magnitude and frequency of flooding, and human-induced climate change is increasing the intensity of storms. Thus, risk can be thought of as the product of hazard, exposure, and vulnerability.
Adaption refers to options that may be taken to reduce exposure and vulnerability, such as insurance, evacuation, engineering to strengthen infrastructure and protect people, and land-use planning to avoid hazardous areas.
Linkages exist between natural hazards.

Human can turn disastrous events into catastrophes.

Consequences of hazards can be minimized.

Linkages exist between natural hazards.

Hazardous processes are linked in many ways.
Climate change with warming oceans and rising sea levels are linked to more intense storms such as hurricanes, as well as to accelerated coastal erosion (see Chapter 12).

Humans can turn disastrous events into catastrophes.

The world's population has more than tripled in the past 70 years.
During the early industrial period (A.D. 1600 to 1800), growth rates increased again by about 10 times, and density of persons increased to about seven persons per km².
Many scientists are concerned that in the twenty-first century it will be impossible to supply resources and a high-quality environment for the billions of people added to the world population.
How many billions to go? Nature 401: 429.
Global warming is a major concern today. Discuss how global warming might influence the magnitude or frequency of hazardous events, disasters, or catastrophes caused by natural hazards.

Consequences of hazards can be minimized.

The role of education is paramount
As people (particularly women) worldwide become more educated, the population growth rate tends to decrease. As the rate of literacy increases, population growth is reduced. Given the variety of cultures, values, and norms in the world today, it appears that our greatest hope for population control is, in fact, through education.

Magnitude and Frequency of Hazardous Events

The impact of a hazardous event is in part a function of the amount of energy released, that is, its magnitude, and the interval between occurrences, that is, its frequency.
In general, the frequency of an event is inversely related to the magnitude. This is the magnitude-frequency concept.

Deadly Catastrophes Resulting From Natural Hazards

Hurricane Mitch and the flooding of the Yangtze River in China, both in 1998; the Indonesian tsunami in 2004 that killed about 230,000 people; and Hurricane Katrina in 2005 that killed at least 1,600 Americans. Hurricane Mitch, which devastated Central America, caused approximately 11,000 deaths, whereas the floods in the Yangtze River resulted in nearly 4,000 deaths.
Land-use planning.

Reactive Response: Impact of and Recovery from Disasters

The effect of a disaster on a population may be either direct or indirect. Direct effects include people killed, injured, dislocated, or otherwise damaged by a particular event. Indirect effects are generally responses to the disaster. They include emotional distress, donation of money or goods, and payment of taxes levied to finance the recovery.