California is a disaster hotspot. These are vulnerable places at risk from two or more hazards. The state of California in the USA has many highly populated towns and cities at risk from a variety of hazards.
1. The San Andreas Fault runs the length of California-it's a conservative plate boundary.
2. Earthquakes occur when pressure between plates builds up and then is suddenly released as they jerk past each other.
3. California has 2-3 earthquakes a year that are powerful enough to damage structures (5.5+ on the richter scale).
4. Studies of their frequency and magnitude of past earthquakes show that there's a good chance of a 7.0+ earthquake hitting the San Francisco Bay area before 2025.
5. Past diasters include the San Francisco earthquake of 1906 (magnitude 7.8) which along with subsequent fires, destroyed much of the city.
1. Droughts in California can be caused by anti-cyclones (long-lasting periods of high air pressure with sinking, dry air. Dry air means no rain.
2. Drought can also be caused by La Nina events (periods when the surface water in the eastern Pacific ocean is cooler). This means less evapouration, so there's less precipitation.
3. Another cause of drought is increased wind blowing westward from the desert areas that are east of California, e.g. Arizona. The dry air has no moisture to cause precipitation.
4. the most devastating effect of drought in California is wildfires-dry vegetation is extremely flammable, so fires spread quickly over wide areas.
5. The wildfires in Southern California in October 2007 killed 22 people and destroyed 1300 homes.
1. A tsunami is a series of large waves that can flood coastal areas.
2. They can be caused by earthquakes on the sea bed, or landslides into the sea.
3. Earthquakes under the Pacific ocean could cause a tsunami along the California coastline.
4. An earthquake off the coast of Alaska in 1964 caused a tsunami to strike the coast of northern California, killing 12 people in Cresent City.
1. Landslides occur on unstable land. Land can be made unstable by coastal erosion or extreme weather (rainstorms). Landslides can also be triggered by earthquakes.
2. The risk of landslide diasters in California is high because of building on and around steep slopes, as well as building on coastal land overlooking the ocean e.g. La Conchita.
1. There hasn't been a volcanic eruption in California since 1915 (Lassen Peak).
2. But there are volcanoes being monitored for potential eruptions, e.g. Lassen Peak, Mount Shasta, and volcanoes arounf Mammoth Lakes.
California is wealthy but Parts of the Population are Vulnerable:
1. More than 70% of California's population live within 50km of a fault line.
2. There's a lot of building on unstable land-this can lead to soil liquefaction during earthquakes (where…