Hazard Relationships & Definitions

Hazard Relationships and Definitions

• Linked hazards involve events influencing each other
• Wildfires can destabilize land, leading to landslides and floods
• Hazards are often unavoidable, forecastable, and predictable dangers capable of causing harm
• Harm affects people, human activities, property, and the environment
• Vulnerability is the degree of susceptibility to hazards, linking environmental relationships to social and cultural values
• Risk equals the probability of occurrence multiplied by the cost of probable loss
• Risk varies among stakeholders, including individuals, families, communities, states, nations, and the globe
• A catastrophe is a long-lasting and complex event that causes sufficient damage with unending rehabilitation

Framework for Hazard Analysis

• Hazards can be predicted through scientific evaluation and risk analysis
• There are linkages between different types of hazards and the environment
• Hazardous events are now catastrophes as a result of increased population, high population concentration, and land usage affecting the magnitude and frequency of events
• The consequences of hazards can be minimized

Prediction vs. Forecasting

• Predictions involve location, time, and intensity/effects, and are more effective with more data
• Predictions are more actionable and are used for evacuation advisories and anticipatory actions
• Forecasting involves probability ranges

Hazards and Human Interaction

• Hazards are natural phenomena that become hazardous when they interfere with human activity
• Human activity can trigger phenomena like earthquakes and seismic activity
• Some hazards can be predicted, but most can be forecasted

Hazard Reduction and Distribution

• Hazard reduction involves identifying the location and probability, observing precursor events, forecasting/predicting, and warning the public
• Data is distributed from scientists to peer review, then to regional officials/the public, then to local officials/the public, and then to the public
• Acceptable risk is the level of risk an individual or society is willing to take

Hazard Linkages and Physical Environment

• Hazard linkages include drought-wildfire, earthquakes-landslides/tsunamis, and flooding-mudslides
• Physical environments are related to hazards such as coastlines vulnerable to hurricanes/tsunamis, limestone ground vulnerable to karst subsidence, plate boundaries vulnerable to tectonic events, and vegetated areas vulnerable to wildfires
• Minimizing consequences involves shifting from reactive to anticipatory responses and completing as much preparation as possible
• These preparations include land-use planning, building codes, insurance, evacuation, disaster preparedness, resilient communities, and educational programs

Exam Topics

• The exam covers drought, wildfire, earthquakes, volcanoes, and tsunamis with unequal point values per section
• Drought section will have 3 questions for 40 points, covering types of drought and responses
• The wildfire section will have 5 questions for 60 points, covering phases, behavior, and an Australian case study
• The earthquake section will have 5 questions for 80 points, covering material amplification (definition, diagram, importance), measurement of earthquakes (Modified Mercalli scale), and man-caused earthquakes
• The volcanoes section will cover types of volcanoes, the Paricutin cinder cone case study, effects, and another case study
• The tsunami section will have 3 questions for 40 points, covering the Indian Ocean case study and instrumentation for monitoring tsunamis

Wildfires: Australia Case Study

• The Aus fires 2009 are a case study of wildfires
• Australia is an arid country, used to wildfires
• 21-day fires involved multiple complexes
• Loss of life led to a reevaluation of the fire policy "stay and defend or leave early"
• Runoff reduction resulted from forest regrowth
• Aid included $1000 to each person and longer-term aid from the government, banks, and companies
• Crowdsourced housing relief was provided by bushhousingfoundation
• Policy was reviewed quickly with a well-prepared home as the best refuge

Fire Processes and Influences

• Fuel includes peat, trees, leaves, twigs, grass, and any organic material
• Landslides, hurricanes, and tornadoes can arrange flammable debris
• Topography causes drier fuels on south-facing slopes in the northern hemisphere
• In mountains, winds circulate up canyons, and wildfires preheat fuel upslope
• Weather effects include drought, and wind direction/strength amplify preheating
• Winds carry embers, which ignite spot fires

Wildfire Types and Geographic Risk

• Types of fires are ground, surface, and crown, which are distinguished by the area they burn (underground, surface, canopies)
• High-risk geographic areas include the west coast, everglades, Texan coast, Appalachia and the Smokies, and the northwest

Wildfire Environment and Effects

• The geologic environment undergoes changes to the soils, creating a water-repellent hydrophobic layer, increased runoff, and erosion
• Soil erosion results from the removal of anchoring vegetation, and precipitation can exaggerate the effects of fires on landslides
• The biological environment is affected through the destruction, weakening, or promotion of different vegetation
• Humans face affected water quality, irritation from smoke and haze, and property destruction

Natural Functions and Wildfires

• Wildfires increase nutrient function and reduce microorganism populations in the soil
• Flora and fauna see a reduction in the number of plant species, seed release in some species, removal of surface litter, recycling of nutrients, and increased plant life for animals

Greece Fires Case Study

• Fires in a national park near Athens affected the microclimate, air quality, and flooding
• There were 100 fires on islands and other parts of Greece
• A farmer was arrested for arson and confessed
• Rewards were offered for information on fire starting, political parties accused each other, and property developers were suspected
• There are laws against clearing native vegetation, but developers wanted fire to clear vegetation for development

Earthquakes - General Information

• Hazards are predictable by scientific evaluation and risk analysis
• Linkages exist between different hazards and the environment
• Hazardous events that used to be disasters are now catastrophes due to human population growth, high population concentration, and land usage
• Consequences of hazards can be minimized

Haiti Earthquake 2010

• Earthquakes are predictable, but in Haiti's case, warnings were not known or distributed
• Risk factors included its location on a fault, island status, poor community, fragile buildings, reliance on imports, lack of emergency infrastructure, and low trust in government
• Earthquake linkages can cause tsunamis and make other hazards worse

Earthquake Effects and Factors

• Earthquakes are not climate-driven, but climate can make recovery more difficult
• Denser development can increase vulnerability due to less space, more material to break down, and more people to help or be hurt
• Anticipatory measures such as warnings, data collection, and community education are important
• Reactionary measures include rescue, infrastructure repair, volunteers, and supplies

Earthquake Case Studies: El Salvador and Bhuj

• El Salvador 2001: 95% of homes in rural areas flattened, landslides, 3000 aftershocks, 852 fatalities, 250k homeless
• Resource costs are significant for displaced people needing shelter, food, and supplies
• Bhuj 2001: M7.6 earthquake on a national holiday, 250 aftershocks, towns leveled, 20k fatalities, $1B damage

Characteristics of Earthquakes

• It is difficult to predict the exact timing of earthquakes, effects are distributed and far reaching
• Defined as the sudden movement of a block of Earth's crust along a geologic fault, releasing accumulated strain
• Variations in effects depend on magnitude, depth, geologic materials, building construction, building location, and distance to population center

San Francisco Earthquake 1906

• R.H. Reid proposed strain and release as the earthquake mechanism
• Liquefaction occurred from the earthquake, causing fires due to ruptured gas lines

Earthquake Measurement and Terminology

• Magnitude is measured on the Moment Magnitude scale (1-9+), which is nonlinear; each unit increase = x10 ground motion, x32 energy released
• Intensity measures the effect of ground motion on people and structures, using the Modified Mercalli Scale (I-XII)
• Seismographs/seismograms record ground motion, acting as EQ fingerprints, and are used to triangulate centers of seismic activity
• Shake maps use seismograph data to show areas of intense shaking
• Ground shaking intensity depends on magnitude, position relative to the epicenter, local soil/ground composition
• Seismic waves are produced by sudden movement and fault ruptures, including body waves (P and S types) and surface waves

Earthquake Wave Characteristics and National Programs

• Surface waves occur when P and S waves reach the surface, are complex with vertical and horizontal motions, are slower, and are more damaging near the epicenter
• The National Earthquake Hazard Reduction Program aims to understand the source, determine potential seismically active regions, predict effects, and apply research results through education and preparation

Earthquake Prediction and Warning Systems

• Short-term prediction involves active research and precursor events like foreshocks, lunar tides, animal behavior, and microEQ swarms
• A one-minute advance warning is technically feasible in CA using seismometers on the SA fault; Japan already has warnings on trains
• The Earthquake Warning Plan involves scientists, USGS, state earthquake prediction review groups, state disaster response groups, regional offices, local officials, and federal offices

Case Studies: Turkey 1999 and Northridge/Armenia

• Turkey 1999: M7.6 and M7.2 earthquakes leveled thousands of buildings, killed thousands, and left hundreds of thousands homeless due to poor construction practices
• Community adjustment involves location of critical buildings, microzonation (prediction of ground motion), structural protection (new codes, retrofitting buildings), education, insurance, and relief measures.
• Northridge/Armenia: M6.8 earthquake resulted in 25,000 deaths and complete collapse as opposed to Northridge M6.7 with 60 deaths, freeway collapse, and more buildings standing

Volcanoes: Tectonic Origins and Locations

• Volcanoes are tectonic in origin, located at mid-ocean ridges, subduction zones, and hot spots beneath oceans or continents
• Regions at risk include plate boundaries (Ring of Fire), hot spots, mid-ocean ridges (Iceland), and rifting zones (East Africa)
• Alaska is the most active in the U.S., activity fluctuates, and eruptions are difficult to predict, but 500 million people live close to volcanoes
• Volcanic activity Primary effects include lava flow, pyroclastic debris/ashfall/flow, and gas release
• Volcanic activity Secondary effects include debris flows, mudflows, landslides, debris avalanches, floods, fires, and global weather effects

Volcanic Activity and Hazards

• Primary lavas are rhyolitic, andesitic, and basaltic, with basaltic lavas flowing most abundantly: Pahoehoe(1m/hour), A'A'(1-3m/day)
• Pyroclastic activity includes explosive tephra, ash (volcanic glass and fine rock shatters), lateral blasts from mountain, pyroclastic flows (avalanches of hot pyroclastic material down mountainsides).
• Ash fall can impact vegetation, health, damage, and aviation risk.
• Gases affect air quality (CO2 displaces breathable air, odorless) and sulfur dioxide causes acid rain

Volcano Case Studies: Lake Nyos and Mt. St. Helens

• Lake Nyos is a case study involving gases emitted into a crater lake, reaching a threshold and outgassing CO2 down the volcano's banks, displacing breathable air, and killing everyone nearby
• Mt. St. Helens followed a 120-year dormancy with seismic activity and groundwater heating in 1980
• The M5.1 EQ on May 15, 1980, triggered a landslide debris/avalanche, followed by a lateral blast from the bulge, losing 1300 feet, now rebuilt to 1150 feet above the crater floor
• Since then, activity has continued and is monitored with seismographs, satellites, gas sampling, acoustic monitors for mudflows, and webcam surveillance

Volcanic Features and Linkages

• Craters are depressions at the top which are the collapse of a cone, which can be very large
• A caldera is a volcanically active depression in the landscape containing vents, hot springs, and explosive activity
• Eruptions are rare but can be dramatic. New Zealand 27,000 years ago, 240-480 cubic miles of material were blown out
• Volcanic vents are openings where lava and pyroclastic material erupt; they can be circular or a fissure and produce flood basalts
• Hot springs and geysers, hot rocks are the source of the heated groundwater discharged at the surface; geysers erupt steam

Volcanic Relationships, Services, and Controls

• Volcano linkages include plate tectonics and magma types dependent on rock composition, related to fires, earthquakes, landslides, and climate change
• Volcanoes provide natural services such as the origin of atmospheric/hydrologic systems, volcanic soils, mineral resources, recreation, and creation of new land
• Controlling lava flow can be done by hydraulic chilling via transport by sea and road with water to divert lava, cooling it to slow it down in Iceland in 1973

Tsunamis: Basic Definitions and Triggers

• Tsunamis are sudden vertical displacements of ocean water with long wavelengths, behaving as shallow water waves
• Energy converts to higher amplitude and shorter wavelength due to shallower depth as the wave approaches land
• Triggers include movements that displace water such as earthquakes, landslides, collapse of a volcano, submarine volcanic explosions, megatsunamis from comet/asteroid impacts. Earthquakes move the seafloor to trigger a landslide with mass displacing seawater to the surface

Earthquake-Tsunami Case Study: Sumatra 2004

• The Sumatra M9.1 earthquake caused 230,000 fatalities and was the most lethal tsunami
• Tsunamis are fast moving, spaced far apart (60 miles), and 3 feet high in the deep ocean then close to land decrease speed to 28 mph with height increasing
• Runup is the movement of the wave inland carrying debris back toward the ocean, also destructive
• 30.5 million m^3 of rock stripped shorelines of trees and lifted boats from the water to 1700 feet

Assessing Tsunami Hazards and Impacts

• Hazard rankings: height of 30m, runup of 5m is considered significant with a global hazard map featuring greatest hazards with return period
• Effects include flooding, erosion, debris load, and Tsunami lung

Tsunami Effects and Natural Services

• The 2004 tsunami in Banda Aceh, Indonesia, led to erosion and obliterated the town
• Natural service includes widescale, death, destruction, material recycling, sorting and nutrients from the sea to land

Tsunami Control and Prediction

• Humans can’t prevent or control tsunamis and are not tied to human activities
• Tsunameters are surface buoys with bottom sensors to detect pressure changes from passing waves using volume changes, relayed via satellite, used with tidal data to predict wave arrival

Tsunami Maps: Before and After

• After tsunami maps show where it went and are useful for future predictions, while before tsunami maps show likely areas of inundation with low probability of accuracy with catastrophic costs
• The Huntington Beach area has 75% city less than 25 feet above sea level with 100k people on the beach in summer

Indonesian Tsunami and Warnings

• Megathrust event led to 900 miles of 65 feet of movement. 75% of deaths, intense shaking, and inundation within 1 hour
• Individuals fled in Thailand and Sri Lanka after seeing a receding Ocean