40:153 Earths internal energy and plate tectonics

Natural disasters

extreme natural events in which a large amount of energy is released in a short time with catastrophic consequences for life and infrastructure in the vicinity

generally involves significant casualties and disruption to society, large economic losses, and calls for exterior help

Hazard

a dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage

Disaster

a serious disruption of the functioning of a community or a society involving widespread human, material, economic or environmental losses and impacts, which exceeds the ability of the affected community or society to cope using its own resources

Frequency

number of occurrences in a given length of time

Return period

the length of time between similar events

Magnitude

related to the amount of energy fuelling a natural event

Examples of natural hazards

Flood

Tornados

Cyclones

Extreme weather

Earthquakes

Volcanic eruptions

Tsunami

Mass movements

Epidemics/pandemics

Extraterritorial materials

Characteristics of natural hazards

Magnitude/intensity

Speed of onset

Duration

Area of extent

Technological hazards

A hazard orientating from technological or industrial conditions, including accidents, dangerous procedures, infrastructure failures or specific human activities, that may cause loss of life, injury, illness or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage

Examples of technological hazards

Industrial pollution

Nuclear radiation

Toxic waste

Dam failures

Transport accidents

Factory explosions

Fires

Chemical spills

Categories of natural hazards

Atmospheric (meteorological)

Geological (earth)

Hydrological (water)

Extraterrestrial

Biological

Technological (anthropogenic) – non-intentional

Technological

Hazardous materials

Environmental

Industrial

Mining

Nuclear

Transportation

Structural

Public safety Canada (PSC)

focuses on managing emergencies (labels an event as a disaster or not)

Four pillars of emergency management

Response

Recovery

Preparedness

Mitigation

Primary energy sources: Earths internal energy

1.     Primarily from the radioactive decay of elements

2.     Smaller contributions from impacts/gravitational compact (earth’s early history)

Primary energy sources: Gravity

1.     Mass movements

2.     Snow avalanche

Primary energy sources: Solar energy

1.     Hydrologic cycle

2.     With gravity powers the agents of erosion

3.     Stored in plants

Primary energy sources: The impact of extra-terrestrial bodies

Asteroids and comets

Origin of the sun and planets: Initial stage

Rotating spherical cloud (ice, gas, debris)

Origin of the sun and planets: Spinning mass

Contracts into flattened disk (planets grow as particles collide and stick together)

Origin of the sun and planets: Ignited sun

Surrounded by planets – earth is the third planet from the sun

Inner planets (rocky planets)

1.     Mercury

2.     Venus

3.     Earth

4.     Mars

Outer planets (icy bodies of He and H)

1.     Jupiter

2.     Saturn

3.     Uranus

4.     Neptune

The oldest solar system materials are about

4.57 billion years old

The oldest earth rocks are

4.03 billion years old (Acasta gneiss, northwest territories, Canasa)

The oldest ages obtained from Earth materials (zircons) are

4.37 billion years old (extracted from a 3.1-billion-year-old sandstone – western Australia)

Our planet has existed for about

4.5 billion years

Massive amount of heat produced widespread melting that caused formation of:

1.     Primitive crust (low-density rock)

2.     Large oceans

3.     Dense atmosphere

The earths layers are based on

Density due to different chemical and mineral compositions

most inner layer of the earth

1.     Core

a.      Inner core

b.     Outer core

second layer of the earth

Mantle

outer layer

Crust

Strength layers Mesosphere

stiff plastic solid – extends from the core mantle boundary – 360km below the earths surface

Strength layers Asthenosphere

soft plastic – surrounds the mesosphere

Strength layers Lithosphere

rigid outer layer- varies in thickness between a few km under oceans to 100km under continents

Tectonic forces form:

Mountains/plateaus

Mid-ocean ridges

Deep ocean trenches

Chains of volcanic islands

how many years does it take to complete the tectonic cycle

250 million years

Centering:

lithosphere moves over centres of anomalously hot mantle regions

Doming:

mantle heat causes surface doming through uplifting, stretching and fracturing

Rifting:

dome’s central area sages – forms valley

Spreading:

advanced pulling apart – forming new seafloor

Triple junction (Afar Triangle)

1.     Northeast Africa being torn apart by three spreading centres:

a.      Red sea

b.     Gulf of Aden

c.      East African rift system

Three classes of collisions:

1.     Oceanic plate-oceanic plate

2.     Oceanic plate-continent plate

3.     Continent plate-continent plate

Oceanic-Oceanic convergence:

formation of a deep offshore trench and seafloor volcanoes that can eventually form an island arc

Oceanic-Continental convergence:

formation of a costal trench and adjacent chain of volcanoes

Shallow hypocentres

earthquakes generated in brittle rocks in both subducting (brown) and overriding (orange) plates

Deeper hypocentres

only the interior of the subducting Pacific plate is cold enough to maintain the rigidity necessary to produce earthquakes 

When all the continents were together it was called

Pangaea

when was pangea formed

220 million years ago