Final Exam Study Guide for Geological Hazards Course

Geological or catastrophic natural event

The consequence(s) of arising from the interaction of a natural hazard with either a human population (present day) or, more generally, life (within Earth history)

Hazard

A source of potential harm; a process, phenomenon or human activity that may cause loss of life, injury, or other health impacts, property damage, social and economic disruption or environmental degradation

Natural hazard

A hazard that originates from natural processes occurring in the biosphere; also includes extraterrestrial hazards (like an asteroid impact as it has significant impacts on the biosphere)

Risk

The probability of harmful consequences; expected loss resulting from interactions between hazards and vulnerable conditions

Probability

The likelihood or degree of certainty that something will occur (0-1 or 0%-100%)

Vulnerability

A set of conditions and processes which affect the susceptibility of a human population to the consequences; 'Vulnerability' and 'susceptibility' are interchangeable terms

Element-at-risk

The 'thing' that is inserted into a hazard; like someone in the middle in an avalanche zone

Exposure

Degree to which population or property is at risk

Resistance

Measures taken to prevent, avoid, or reduce loss

Resilience

Ability to recover prior state or achieve desired post-disaster state ('ability to cope')

Consequence

The negative result of an interaction of a hazard with a human population (or life, more generally)

Lahar

Fast-flowing mud slide originating from a volcano

Mount Rainier Example - Hazard

The possibility of a Lahar reaching Puget Sound

Mount Rainier Example - Probability

10% chance of a lahar reaching the Puget Sound during a human lifetime

Mount Rainier Example - Exposure

Living in an old lahar deposit area

Mount Rainier Example - Resistance

Beefing up building codes in vulnerable areas, or not letting people live there

Mount Rainier Example - Resilience

The ability to rebuild after being wiped out by a lahar

Mount Rainier Example - Vulnerability

The people that live on old lahar deposits are especially vulnerable

Mount Rainier Example - Consequence

People die, houses are wiped away from a lahar

Natural hazards covered in this course

Landslides, Flooding, Hurricanes, Earthquakes, Tsunamis, Volcanic eruptions, Asteroid impacts

Age of Earth

4.567 Ga

Formation of Earth

Formed from a rotating disk of dust and gas (first suggested in 1755)

Accretion

Process of small, solid particles growing into asteroids and planets

Differentiation

Separation of materials in a planetary body according to density and chemical affinity

Ecliptic Plane

All planets in same plane and orbit in the same direction

Basic layout of the solar system

With sun in the middle, next come the small and rocky bodies, then large and gas-rich, finally the small and icy bodies.

Broad history of the Earth

Modern plate tectonics, and the expansion of life on land (0.6 Ga to present)

Stabilization of continental platforms

Oxidation of the atmosphere (2.5 to 0.6 Ga)

Development of early continents

Origin of life (3.8 to 2.5 Ga)

Period of intense meteorite bombardment

Accretion, followed by period of intense meteorite bombardment (4.6 to 3.8 Ga)

Law of original horizontality

Sedimentary layers and deposited horizontally; layers are horizontally continuous

Law of superposition

In a sequence of sedimentary rock layers, each layer of rock is older than the layer above it and younger than the rock layer below it

Law of cross-cutting relationships

If a fault or other body of rock cuts through another body of rock then it must be younger in age than the rock through which it cuts

Law of inclusions

One rock included in another is older than the rock that includes it

Crust

Outermost layer, on top of mantle - Different composition from the mantle

Mantle

Upper and lower - Includes the asthenosphere

Core

Mostly iron metal (very dense) - Solid inner, liquid outer

Asthenosphere

The top part of the upper mantle (10-250km) where it is weak (plastic, able to flow), and partly molten (close to its melting point) - NOT MAGMA

Lithosphere

Includes the rigid part of the mantle and the overlying crust

Rock cycle

Begins with the formation of new rock material through crystallization of magma.

Igneous rock

An igneous rock is formed from the solidification and crystallization of a cooling magma.

Plutonic Rock

A rock formed from magma that crystallizes slowly beneath the Earth's surface.

Intrusive Rock

A type of rock that forms from magma that cools and solidifies within the Earth's crust.

Lava

Magma that rises to Earth's surface quickly and remains molten.

Sedimentary Rock

A rock composed of compacted or cemented grains that have become lithified.

Clastic Sedimentary Rock

Rocks formed from the products of mechanical weathering of pre-existing rocks.

Chemical/Carbonate Rock

Rocks that form through the precipitation of minerals from solution, often due to evaporation or chemical reactions.

Metamorphic Rock

A rock that has formed through the re-crystallization of a pre-existing igneous or sedimentary rock.

Re-crystallization

The process where original minerals in a rock become bigger and interlock more tightly or are replaced by different minerals.

Pressure in Geology

Increases in pressure can cause rocks to deform through compression, compaction, straining, and folding.

Geologically Active

Refers to regions of the Earth that experience significant geological processes such as tectonics, erosion, and sedimentation.

Plate Tectonics

The theory explaining the movement of the Earth's plates and the geological activity associated with their interactions.

Water Cycle

The continuous movement of water through evaporation, condensation, and precipitation, influencing erosion.

Atmospheric Processes

Processes such as wind erosion that shape the Earth's surface.

Tidal Activity

The influence of the Moon on the Earth's tides, affecting geological processes.

Climate Stabilization

The stabilization of climate conditions influenced by the Earth's orbital characteristics.

Earth's Axis Tilt

The tilt of the Earth's axis at 23.5°, which contributes to seasonality.

Goldilocks Zone

The average temperature of 15 °C that allows for liquid water to exist on Earth.

CO2 Weathering Cycle

The cycle where increased CO2 leads to higher temperatures, increased weathering, and subsequent CO2 drawdown.

Messinian Event

A geological event where the Mediterranean Sea became disconnected from the world's oceans and desiccated about 5.6 million years ago.

Zanclean Flood

The event where Atlantic waters rapidly refilled the Mediterranean Sea approximately 5.33 million years ago.

Flood Discharge Rates

Water flow during the early stages of flooding implying discharges of about 100 million m³/s.

Sea Level Rise

The peak rates of sea level rise in the Mediterranean during the flood, exceeding ten metres per day.

Weathering

Set of physical and chemical processes that alter states of rock and minerals at (or near) the earth's surface

Erosion

Transport or movement of materials at the earth's surface

Physical/Mechanical Weathering

Breaking up of rocks and minerals by physical processes

Disintegration

Breaking apart of materials into smaller pieces

Freezing and Thawing

Process where water freezes in cracks of rocks and expands, causing the rocks to break apart

Tractive Forces

Forces that cause materials to move along a slope

Shear Strength

Resistance of a material to sliding or deformation

Shear Stress

Force per unit area acting parallel to the surface of a material

Driving Forces

Forces that push materials down a slope, including gravity, moisture, precipitation, pore water pressure, slope, loading, and tectonics

Resisting Forces

Forces that oppose movement down a slope, including sediment/rock cohesive strength, cements, vegetation, and structure

Types of Landslides

Classified as rock, debris, or earth

Falls

Rapid, free fall, rolling, bouncing movement of materials

Topples

Rapid rotation of a mass about a point

Slides

Movement along one or more distinct surfaces

Rotational Slide

Curved plane of failure, also known as slumps

Translational Slide

Planar failure plane

Lateral Spreads

Lateral movement of the ground usually accompanied by subsidence

Flows

Viscous fluid movement, ranging from slow to fast

Complex Landslide

Combination of two or more landslide types

Edmonton Grierson Hill Landslide

Happened in 1901 during wet weather, influenced by coal mining

Mitigation

Includes any efforts to reduce the risk, minimizing vulnerability

Active Layer Detachment Slide

When the active layer of the permafrost begins to thaw to the point where sheer strength < sheer stress, causing the active layer to slide down a slope

Thaw Slump

An area of thawing that continues to thaw due to exposure of underlying sediments from the side

Permafrost

Any ground that remains below freezing (0 °C) for at least 2 years in a row

Hazards of Permafrost Landslides

Degrading ice wedge polygons and thaw lakes found in continuous and discontinuous permafrost regions

Retrogressive thaw flow slide

A type of landslide resulting from thawing permafrost.

Deep seated base of permafrost failure

A failure occurring deep within the permafrost layer.

Large scale thaw induced landslides

Landslides that occur due to thawing of frozen ground.

Pre-existing disturbances

Conditions that exist prior to a rapid failure event.

Surficial bedrock

The uppermost layer of bedrock exposed at the surface.

Hydrologic cycle

The continuous movement of water on, above, and below the surface of the Earth.

Evaporation

The process where heat from the sun causes water to turn into vapor.

Condensation

The process where water vapor cools and turns into droplets or ice crystals.

Precipitation

The falling of water droplets from clouds as rain, snow, sleet, or hail.

Collection

The gathering of water that falls back to Earth in rivers, lakes, and oceans.

Flood

When discharge in a river exceeds the river's capacity.

Stream

A body of flowing water confined to a channel.