CALIFORNIA- Disaster hotspot case study

Flashcards by caryyon, updated more than 1 year ago
Created by caryyon about 7 years ago


A Levels Geography Flashcards on CALIFORNIA- Disaster hotspot case study, created by caryyon on 02/14/2014.

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CALIFORNIA IS A DISASTER HOTSPOT: A disaster hotspot is a vulnerable place at risk from two or more natural hazards. The state of California is located along the western coast of the USA, in the Northern Hemisphere. It is home to many highly populated towns and cities which are at risk from a variety of hazards e.g. San Francisco and Los Angeles.
EARTHQUAKES: The San Andreas fault runs the length of California- its part of the conservative plate boundary between the Pacific plate and the North American plate. Earthquakes occur when pressure between the plates builds up and is suddenly released as they jerk past each other.
California has two or three earthquakes each year which are powerful enough to damage structures (5.5+ on the Richter Scale). Studies of the frequency and magnitude of past events show that there is a good chance of an earthquake of magnitude 7.0+ hitting the densely populated 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. The Loma Prieta earthquake of 1989 was another major Californian earthquake which highlighted the dangers of building on unstable ground.
DROUGHT: Droughts in California can be caused by anticyclones (long-lasting periods of high air pressure with dry, sinking air). Dry, sinking air means no rain. Droughts can also be caused by La Nina events (periods where the surface water of the eastern Pacific Ocean is cooler). This means less evaporation which means less precipitation.
Another cause of drought in California is increased winds blowing westwards from the desert areas east of the state e.g. Arizona. The dry air contains 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 which can flood coastal areas.
They can be caused by earthquake on the sea bed or landslides into the sea. An earthquake under the Pacific Ocean could cause a tsunami along the Californian coastline.
A tsunami off the coast of Alaska in 1964 caused a tsunami to strike the northern coast of California, killing 12 people in Crescent City. LANDSLIDES: Landslides occur on steep, unstable ground. Land can be made unstable by coastal erosion or extreme weather (rainstorms).
Landslides can also be triggered by earthquakes. There is a high risk of a landslide disaster in California because of building on an around steep slopes, as well as on coastal land overlooking the ocean e.g. La Conchita, which suffered a landslide in 2005.
VOLCANOES: There hasn't been a volcanic eruption in California since 1915 (Lassen Peak). However, a number of volcanoes in the area are being monitored for signs of a potential eruption e.g Lassen Peak, Mt Shasta an the volcanoes around the Mammoth Lakes.
Although California is a wealthy state, parts of the population are still vulnerable. More than 70% of the population live within 50km of a fault line.
Lots of buildings are constructed upon unstable land which increases the risk of soil liquefaction (where the ground becomes more like a liquid) which can damage buildings an cause landslides. This was a major problem during the Loma Prieta earthquake. There are lots of coastal buildings which are vulnerable to tsunamis.
Around 20% of Los Angeles residents live below the official poverty line. It is these people who have the lowest capacity to cope with the effects of a natural hazard. California has a massive economy so any economic losses as a result of a disaster would most likely be huge.
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