California Hotspot

  • Created by: keeels
  • Created on: 07-05-14 21:25
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  • California
    • The state of California in the USA has many highly populated towns and cities at risk from a variety of hazards.
    • Earthquakes
      • The San Andreas fault runs the length of California- it's a conservative plate boundary
      • Earthquakes occur when pressure between the plates builds up and then is suddenly released as they jerk past each other
      • Califronia has two or three earthquakes each year that are powerful enough to damage structures (5.5+ on the Richter scale)
      • Studies of the frequency and magnitude of past earthquakes show that there's a good chance of an earthquake of magnitude 7.0+ hitting the San Francisco Bay area before 2025
      • Past disasters include the San Francisco earthquake of 1906 (thought to have measured 7.8) which along with subsequent fires, destroyed much of the city
    • Droughts
      • Drought in California can be caused by anticyclones (long lasting periods of high air pressure with sinking, dry air) Dry, sinking air means no rain.
      • Drought can also be caused by La Nina events (periods when the surface water in the eastern Pacific Ocean is cooler). This means less evaporation, so there's less precipitation
      • Another cause of drought is increased wind blowing westward from the desert areas that are east of California, e.g from Arizona. The dry air has no moisture to cause precipitation
      • The most devastating effect of drought in California is wildfires - dry vegetation is extremely flammable, so fires spread quickly over wide areas
      • The wildfires in southern California in October 2007 killed 22 people and destroyed 1300 homes
    • Tsunamis
      • A tsunami is a series of large waves that can flood coastal areas
      • They can be caused by earthquakes on the sea bed, or landslides into the sea
      • Earthquakes under the Pacific Ocean could cause a tsunami along the California coastline
      • An earthquake off the coast of Alaska in 1964 caused a tsunami to strike the coast of northern California, killing 12 people in Crescent City
    • Landslides
      • Landslides occur on unstable steep land. Land can be made unstable by coastal erosion or extreme weather (rainstorms). Landslides can be triggered by earthquakes
      • The risk of landslide disaster in Califronia is high because of building on and around steep slopes, as well as building on coastal land overlooking the ocean e.g La Conchita
    • Volcanoes
      • There hasn't been a volcanic eruption in California since 1915 (Lassen Peak)
      • But there are volcanoes being monitored for potential eruptions, e.g Lassen Peak, Mount Shasta and the Volcanoes around Mammoth Lakes
    • Vulnerable Population
      • More than 70% of California's population live within 50km of a fault line
      • There's a lot of building on unstable land - this can lead to soil liquefaction during earthquakes (where the ground can become more like a liquid), which damages buildings and increases the risk of landslides. This was a major problem during the Loma Prieta earthquake in 1989
      • There are many buildings along the coast that are vulnerable to tsunamis
      • California is a wealthy state, but there are very poor areas within it - around 20% of the residents in Los Angeles live below the official poverty line. These people have the lowest capacity to cope when affected by a hazard
      • Califronia has a massive economy, so there are likely to be huge economic losses when a disaster occurs


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