Physical Geography

Tsunami are primarily ________ hazards?

Geological

Tropical Cyclones are primarily ________ hazards?

meteorological

Describe the speed and period of tsunami waves

A tsunami is a series of fast-moving, long-period waves

What is the primary cause of a tsunami?

They are most often generated by large disturbances below or near the sea floor

What his the highest speed of a tsunami?

800 kilometers per hour

What is the wave period of wind waves?

6-12 seconds

What is the wave period of tsunami waves?

15 to 60 minutes

Why might you only see one tsunami wave at a time?

Because the wave period can be from 15 to 60 minutes so the second wave may not be visible.

What is the ultimate cause of tsunami?

Water displacement

Name the 4 ways a tsunami develops

Sub-marine earthquakes, landslides, volcanic eruptions, meteorites

What is the largest wave length of a tsunami wave?

500 kilometers .

What is wave length?

Distance between waves

Why are tsunami more dangerous in shallow water?

friction with the seafloor slows the wave, causing it to grow in height

What is the most dangerous part of a tsunami?

being sucked back offshore

What can a tsunami look like?

1. Giant waves

2. A rapidly rising tide with no distinct wave front

Name 3 short term impacts of tsunami

- Loss of life and displacement .
	- Loss of food and water supplies .
	- Damage to sanitation systems leading to contamination .

Name 5 of 7 long term impacts of tsunami

- Environmental damage (salinisation of land, affecting agriculture) .
- Contaminated water supplies .
- Communication and access issues .
- Health issues (waterborne diseases) .
- Economic hardship (loss of livelihoods) .
- Social issues, including demographic changes (e.g., higher death toll among women and children in some regions due to men being at sea or inland) .

How does tsunami effect crop growth?

The salinisation of the land stunts the crops through dehydration, nutrient imbalances, and toxicity.

How are food and water supplies impacted by a tsunami?

The water becomes contaminated and the crops are stunted through salinisation.

How does communication change after a tsunami?

Tsunamis can destroy infrastructure for digital communication and power while also destroying roads which further slows communication.

How do health issues arise from tsunami?

Freshwater wells are contaminated with salt water and sewerage lines are broken causing waterborne diseases.

How does long term economic hardship occur after tsunami?

Economic activity requires a way to move goods and people. Economic hardship is often worsened by a country's lack of wealth. Livelihoods are lost through death and destruction.

What types of social issues arise from tsunami?

1. Mass Displacement and Loss of Community

2. Demographic changes and future imbalance. (higher death of women being on the coast in homes whereas men are in the fields which is generally inland) The lack of women further reduces population growth.

3. PTSD and grief.

Why would a tsunami be a rapidly rising tide over a large wave?

Due to the deep surrounding ocean and lack of a continental shelf

Why can tsunami alarms be ineffective? (3)

1. False alarms PWS has a 75% chance of a tsunami warning being a false alarm

2. Tsunami hazard zones alarms being stolen

3. Funding challanges

What is spatial scale?

How things change in size

What is temporal scale?

How things change over time

What are geological hazards?

Hazards related to geological features (e.g., earthquakes, volcanic eruptions)

What are meteorological hazards?

Hazards related to climate (e.g., drought, wildfire, climate change, sea level change, tropical cyclones) .

What are biological hazards?

Hazards related to living organisms (e.g., viruses like COVID-19)

Are tsunami related to tides?

No, the term ‘tidal wave’ is a misnomer.

What is a tropical cyclone characterized by?

Low pressure, high winds and heavy rain.

What is the difference between a tropical cyclone, a typhoon and a hurricane?

They are named based on their location but cyclones turn clockwise and typhoons and hurricanes turn anti-clockwise.

Why do a tropical cyclones, typhoons and hurricanes turn in different directions?

The direction of rotation differs based on the hemisphere due to the Coriolis force.

What type of pressure does a cyclone need?

Low pressure

Why does a cyclone need low pressure?

Because the center of a cyclone has extremely low pressure, it "sucks" in air from the surrounding high-pressure areas

Why does air pressure matter for cyclones?

Air always wants to move from areas of high pressure (where air is heavy and pushing down) to areas of low pressure (where the air is "lighter").

What strength of winds do you need at high levels?

Light winds (known as wind shear)

What happens if you have strong high level winds?

The storm falls apart.

Why do strong high level winds destroy a cyclone?

Strong High-Level Winds push the top of the storm in a different direction or at a different speed than the bottom. This "tilts" the storm and disrupts the organized flow of air, causing the tropical cyclone to disintegrate or fail to form in the first place

What are the 6 requirements for a tropical cyclone?

1. A large body of water

2. Warm ocean surface (>26.5)

3. Wind blowing across the ocean surface

4. Low pressure

5. Coriolis force

6. Light winds at high levels (wind shear)

What is Coriolis force?

Caused by the earths rotation

Objects in northern hemisphere turn right

Objects in the couthern he

List the 7 steps to forming a tropical cyclone

1. Warm air develops above the ocean, as it warms it rises

2. Winds blow air to replace the rising air and it is also warmed

3. The rising air (containing lots of moisture) reaches the atmosphere and begins to cool and condense into large clouds.

4. Low pressure and upward air movement attracts more air and results in more condensation and higher clouds.

5. Condensation releases heat in water and this powers the storm and results in even higher clouds

6. Coriolis force causes the air to spiral (direction dependent)

7. The storm matures and the eye is created. Once spinning winds reach 120km/hr it is a tropical cyclone.

What are the 3 regions of a tropical cyclone?

1. Eye

2. Eyewall

3. Rainbands

How wide is the eye of a cyclone?

30-50kms

What is the eye of a cyclone characterised by? (4)

1. Clear skies

2. Warm weather

3. Light winds

4. No rain

What is the eye wall of a cyclone characterised by? (4)

1. Maximum wind speed

2. Heaviest rain

3. Lightening

4. Updraft creating convective clouds

What is the raindbands of a cyclone characterised by? (3)

1. Exist on the edge

2. Spiral around core

3. Heavy rain

Where do tropical cyclones usually occur?

20 degrees from the equator

Where do tropical cyclones get their energy from?

Large bodies of warm water

What will cause a cyclone to lose energy? (3)

1. Going over colder seas

2. Going over land

3. Strong wind shear

How many categories are in the hurricane wind scale and which is the most dangerous category?

5

What geographical impacts to tropical cyclones have? (3)

1. Wind damage

2. Heavy rain

3. Storm surge

What components form storm surge and what percentage do they contribute?

Wind setup (95%) and pressure set up (5%)

What is storm surge?

Storm surge is the abnormal elevation of the sea surface at the coast caused by a storm. Think of it like the entire ocean level rising up and moving inland, rather than just individual waves crashing.

How does wind set up contribute to storm surge?

Strong winds from the cyclone push the surface water toward the shore. When that water hits the coastline, it has nowhere to go, so it "piles up" against the land.

How does a cyclone move after it is formed?

They follow tracks made by surface winds.

Name 6 causes for short term changes in sea level

1. Tides

2. Winds

3. Floods

4. Earthquakes/tsunami

5. Atmospheric pressure

6. Changes in water volume (temperature and salinity)

Name 5 causes for long term changes in sea level

1. Ice Age Cycles: Water locked up as ice lowers sea level; melting ice raises it.

1. Thermal Expansion: Warmer water occupies more volume.

2. Basin Size Changes: Tectonic plates shifting can expand or contract the basin.

3. Isostatic Adjustment: Land rising or falling due to ice load changes.

4. Changes in Water Volume: Primarily from ice melt (global warming) or accumulation.

Why does thermal expansion effect water volume?

When water is heated, molecules gain energy, move more, and occupy more space. This causes the water level to rise.

What is isostatic adjustment?

When the Earth's crust adjusts vertically in response to the addition or removal of heavy loads, such as ice or sediment. This process causes changes in local sea level relative to the land. (Vertical movement of land impacting sea levels)

What is the hydrological cycle?

The movement of water between oceans, atmosphere, and land.

During the last ice age (21,000 years ago) what was the sea level relative to today?

120m lower

What is the highest relative recorded sea level and when was it?

120,000 years ago the sea level was 5-6 meters higher than today

How many degrees warmer was the Earth when sea level was 5-6m higher than they are today?

3-5 degrees warmer

What are the 2 main contributors to SLR, by what percentage and how many mm?

1. Melting glaciers and Ice sheets (Just over 50%, 1.8mm/yr)

2. Thermal Expansion (Just under 50%, 1.4mm/yr)

What geological evidence of SLR is there?

Coastal Stacks in the Bahamas: These tectonically stable locations show wave-cut notches about 5 meters above current sea level.

What was the mean global SLR between 1901-1990?

1.35mm/yr

What was the mean global SLR between 1993-2018?

3.25mm/yr

Would a melting iceberg result in SLR, why or why not?

What areas are most likely ot be effected by SLR? (4)

1. River deltas

2. Lowland coastal

3. Low lying mainland areas

4. Coral atolls

What places are most likely to be effected by SLR? (7)

1. Africa

2. South East Asia

Islands in the

3. Indian ocean

4. Pacific ocean

Deltas of

5. Bangladesh

6. Vietnam

7. Myanmar

What is different about SLR in the pacific?

Small increases are combined with large variations in sea level due to due to the El Nino Southern Oscillation.

What is the predicted SLR for 2100?

0.29-1.1m or up to 1.35m

What are some global solutions to SLR?

Mitigate global warming by reducing greenhouse gasses