geology midterm 1

What a disaster is vs. a natural hazard

Natural hazards are processes that have the potential to cause harm, but disasters only happen when vulnerable populations interact with those processes

That the size and frequency of hazardous events are inversely proportional

The size and frequency of hazardous events are inversely proportional: the larger the event, the less frequently it occurs.

Small events (e.g. minor earthquakes) happen frequently.

Large events (e.g. major earthquakes) happen rarely.

Big events are rare, while small events are common.

How can hazardous geological processes benefit the Earth system?

Even hazardous processes often serve a role in the earth system that is beneficial (natural service functions)

Volcanic eruptions: Create new land and produce fertile soils.

Earthquakes: Help shape Earth's surface and release built-up tectonic stress.

Floods: Deposit nutrient-rich sediments and replenish floodplains.

How does racism and poverty intimately link to risk of hazard

Exposure: Racism and poverty can force disadvantaged communities to live in hazard-prone areas.

Vulnerability: Poor housing, limited healthcare, and lack of resources make people more susceptible to harm.

Coping capacity: Poverty and discrimination can limit access to emergency services, insurance, evacuation, and recovery support.

Hazard: Racism and poverty generally do not cause the hazard, but they can increase its impacts.

What is the equation for risk

Risk = Hazard + exposure + vulnerability + coping capacity

The potential for a natural event will occur, and its ability to cause harm or damage

Hazard

whether people are affected

Exposure

how susceptible people or things are to hazard

Vulnerability

Ability to get back on your feet or for the government to respond

Coping Capacity

What factors of the risk equation cause Hati to be at a far greater risk than the DR despite sharing an island

Exposure: Both countries experience similar regional hazards, including earthquakes, hurricanes, and floods. However, the number of people and buildings in dangerous locations can differ.

Vulnerability: Haiti has widespread poverty, weaker housing and infrastructure, and limited access to essential services, making people more likely to suffer damage and loss of life.

Coping capacity: Haiti generally has fewer resources for emergency response, healthcare, disaster preparation, and rebuilding.

Hazard: Both countries share similar tectonic and climatic threats, although local conditions and the precise location of an event affect its severity.

Haiti's greater disaster risk is largely due to higher vulnerability and lower coping capacity, rather than simply experiencing more natural hazards.

Have deaths from natural disasters increased or decreased over the past few decades? Why or why not

Deaths from natural disasters have generally decreased because humans are better at predicting, preparing and responding to disasters.

Have natural disasters increased or decreased over the past decades? Why or why not

Natural disasters have seemed to increase mainly due to better reporting.

The World Meteorological Organization reported a fivefold increase in weather, climate and water-related disasters between 1970 and 2019, driven by a combination of climate change, more extreme weather, and improved reporting.

Why it is difficult to say for certain how the frequency of natural disaster has changed over the past century

It is difficult because historical records are often incomplete, and modern technology allows more disasters to be detected and recorded than in the past. Different countries also use different methods to define and record disasters, while natural hazards fluctuate over time.

Why some people find the term ‘natural disaster’ problematic

The term "natural disaster" is problematic because the natural event itself does not automatically cause a disaster. The level of damage and loss of life causing it to be a “disaster” is based on the human factors that create risk.

Calling it a “natural disaster” can overlook social inequalities and suggest that the consequences are entirely natural, when many impacts could be reduced through better planning and protection.

From outer to inner, what is the order in which the earth is formed

1. Crust

2. Mantle

3. Outer core

4. Inner core

What is the crust composed of and its state of matter

Composed of solid silicate materials

What is the mantle composed of and its state of matter

Composed of iron and magnesium rich rocks and is solid but flows

What is the outer core composed of and its state of matter

Composed of iron and is liquid

What is the inner core composed of and its state of matter

Composed of hot iron and is solid (also has the pressure of 48 000 elephants)

Who is Oldham

Geologist who studied seismic waves from earthquakes. He discovered evidence that earths core was distinct from the mantle because seismic waves changed speed and behaviour as they travelled through earth.

What is the relative thickness of the oceanic crust

5-10km thick

What is the relative thickness of the continental crust

30-50km thick

How far have we drilled inot the crust

~12km

How do s-waves interact with the outer core and why is this usefu;

S-waves are earthquake waves that travel through solids but not liquids therefore cannot travel through the outter core.

This creates an S-wave shadow zone on the far side of Earth, where direct S-waves are not detected

This was useful to prove that the outter core is liquid but also the shadow helps

Where in Nova Scotia can you go to see the mantle

What is the lithosphere

What is the asthenosphere

How do the lithosphere and asthenosphere differ

What is isostacy

How does isostacy relate to the asthenosphere

Who Alfred Wegner was and the main lines of evidence he offered for continental drift

What is Marie Tharp’s contributions to plate tectonic theory

What are the key elements of plate techtonic theory

Why are there a mountain range in the middle of the Atlantic Ocean (and in other parts of the ocean)

Why there is a barcode-like pattern of magnetized rocks on either side of a spreading ridge (the Vine, Mathews, and Morley story!)

Explain the slab pull and ridge push power plate tectonics****

What is a fault and what are the three main types

How does the elastic rebound theory explain earthquakes**

What is magnitude and what three factors influence it

How much ground motion & energy released increases with each step in magnitude scale

What intensity is (MMI) and how it differs from magnitude

Where do the very largest earthquakes occur (boundary type) and why

What types of fault puts Vancouver and California at danger, respectively

What are the types of seismic wave

P waves, S waves, Rayleigh waves, and Love waves

What is the danger of Love waves

What is the danger of P-waves

What is the danger of S-waves

What is the danger of Rayleigh waves

How are p and s-waves are used to triangulate earthquake epicentres/foci

Why is Mexico city is particularly vulnerable to earthquakes

Why buildings of specific heights are impacted by seismic waves of specific frequency

What is liquefaction

What are the conditions required for liquefaction to occur

What are the direct impacts of earthquakes, i.e., ways they can directly kill or damage things

What are the Indirect earthquake impacts:

Why are fires such a problem after earthquakes

How is post-glacial rebound related to intraplate earthquakes in Canada

How do scientists determine the recurrence interval of earthquakes

What are the linkages between earthquakes and other hazards

How can people cause earthquakes

What types of building materials are more at risk from earthquake shaking

Where in Canada has the highest earthquake risk

Why are fires so danergous during an earquake

How is the timing of arival of the earthquake waves can be used to create an early warning system

Most meteors are made of what

Mostly rock, with a moderate amount of iron

What is the difference between continental crust and oceanic crust

Continental crust is thicker, older and contains materials that are richer in silica, causing them to be less dense (felsic) and rise above oceanic crust. Oceanic crust is thinner, younger and contains minerals with less silica but denser minerals (iron and magnesium) (mafic)

What is the distinction between continental and oceanic crust interactions between plate techeonics

When plates collide, a plate boundary with oceanic crust

will sink beneath a plate boundary continental crust

.

What is it called when oceanic crust sinks beneth continental crust and what happens to that oceanic crust

Subduction. Subducted oceanic crust will sink to the bottom of the mantle in which it is destroyed.

Who is Mohorovicic

Geophysicist who discovered a boundary between Earth's crust and mantle, now called the Mohorovičić discontinuity (Moho). He identified it because seismic waves suddenly increased in speed in this boundary.

Who is Inge Lehmann

Seismologist who studied earthquakes and discovered evidence that Earth has a solid inner core surrounded by a liquid outer core.

Why did the contributions of Oldham, Mohorovičić, and Lehmann matter