The tectonic Hazards
- Created by: Julianne :)
- Created on: 21-01-14 20:17
View mindmap
- The tectonic hazards
- Earthquakes
- A sudden and intense shaking motion that usually lasts for a few secons. It is caused by the 'Snapping' of rocks as enormous stresses, which may have built up over many years, are suddenly released
- PRIMARY
- Ground shaking
- SECONDARY
- Fires
- Case studies : - Armenia 1988, Mexico City 1985
- Mexico City 1985 - Long waves , Nature of surface (Dried up lake bed)
- Vast majority occur on plate margins
- EFFECTS
- Nature of the bedrock
- Strenght of the earthquake
- Depth of focus
- Wealth of a country
- Building design and competance
- Population distribution
- Loma Prieta epicentre - San Francissco 1989
- Primary - Marina district badly effected (27 fires)
- Volcanoes
- Pyroclastic flow
- Humans can't out run them
- PRIMARY
- Kills in seconds
- Occur under high pressure
- Speeds of 200+kph
- Reach upto 800 Degrees C
- Case studies : - Mt Unzen, Japan 1991 - 34 killed, Mt St Helens 1980, Mt Vesuvious, Soufriere Hills, Monserat 1995-97
- Only about 50 volcanoes are likely to errupt in a year and on average the death toll is 10% that of earthquakes
- Basalt flow
- PRIMARY
- Humans are able to out run them
- SECONDARY - Fires
- Predictable - not too hazardous
- Lava plateau
- Rilavea, Hawaii
- Tephra
- Airbourne volcanic rock/ash
- Consists of many rock types
- Ash less than 2mm
- Ash cloud
- Can cause buildings to collapse under its sheer wieght
- Icelandic volcano hazard
- Ground flights - air traffic
- Reduces visability
- Bombs
- Larger than 64mm
- Landslide
- SECONDARY
- Mt St Helen's
- Tsunami
- Undert he sea, large ocean waves, earthquakes - Soufriere Hills 1997
- Displacement of water
- Flooding
- Lahars
- Landslides blocking rivers causing quakelakes
- Significant flooding
- Jokulhlaups
- Grimsvoth 1996
- Volcanic eruption under glacier
- Melts the glacier to form a glacial lake
- SECONDARY
- Famine
- Economic distruption
- Loss of jobs, less jobs, less opportunities, SOL reduces
- Crops destroyed
- Decimated food supply
- Problem for subsistent farmers (LEDCs)
- Economic distruption
- Famine
- Volcanic gases
- SECONDARY - Global warming
- Enormous cloud of CO2 - Silent and deadly
- Lake Nyos, Cameroon - PRIMARY HAZARD - Killed over 1700 people
- Lahars
- When pyroclastic mixes with mud and water causing volcanic mud flows
- SECONDARY
- Most eadyl products of an eruption because they flow very fast down the river valledy, demolishing property and bridges, and litterally burying people alive in what amounts to a quick-setting cement
- Thick hot slurry
- Case studies : - Phillipines 1991, Nevada Derruiz 1985 - 23,000 killed in Armero
- Pyroclastic flow
- Liquifaction - when soil and rock acts like a liquid, buildings can collapse or become unstable
- As a result of seismic waves running through the rock and soil
- Earthquakes
Comments
No comments have yet been made