Geography AS level revision

Natural hazard - a natural process that poses a potential threat to human life or property

Hydrometeorological hazard - caused by climatic processes

Geophysical hazard - caused by land processes

Natural disaster - when a hazard seriously affects humans

Risk - The likelihood that humans will be seriously affected by a hazard

Vulnerability - How susceptible a population is to the damage caused by the hazard

Capacity to cope - the ability to deal with the consequences of a hazard

Constructive plate boundary - 2 plates moving apart

Destructive plate boundary - 2 plates moving together

Conservative plate boundary - 2 plates moving side by side

Continental crust - is thicker but less dense and mostly above sea level

Oceanic crust - is thinner but more dense and mostly below sea level

Subduction zone - when the pressure builds between 2 plates in a conservative plate boundary, causing the pressure to be eventually released as the oceanic plate subducts 

Tropical cyclones/hurricanes/typhoons - are big storms with strong winds and torrential rain

Disaster hotspot - a vulnerable place at risk from 2 or more hazards

San Andreas Fault - Conservative plate boundary

Past disasters include the San Francisco earthquake of 1906 thought to have measured 7.8.

Some hazards can increase the likelihood of other hazards occuring

Droughts - caused by anticyclones (long lasting periods of high air pressure with dry sinking air leads to no rain). Can be caused by La Nina - leads to less evaporation and precipitation. Can also be caused by increased wind blowing westward from desert areas in east California. Causes wildfires.

Tsunamis - can be causedd by earthquakes on the sea bed or landslides into the sea. Earthquake of the coast of Alaska in 1964 caused a tsunami to strike north Californian coast - killed 12 people in Crescent City 

Landslides - Land can be made unstable by coastal erosion or extreme weather or earthquakes. Risk of landslides high because there's a lot of building on steep slopes.

Volcanoes - Hasn't been a volcano eruption since 1915 (Lassen Peak). 

Population is vulnerable - More than 70% of population within 50km of a fault line. Lots of building on unstable land- can lead to soil liquefaction during earthquake increases risk of landslide - Loma Prieta earthquake of 1989. Building along coast.20% of residents in LA live below poverty line - have lowest capacity to cope.