Disaster Hotspot Case Study-California Flashcards
What is a disaster hotspot
Vulnerable places at risk of 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
Earthquakes at California
The San Andreas fault runs the length of California-conservative plate boundary
They occur when pressure builds up between the two plate and then is suddenly released as they jerk past each other
California has two/three earthquakes each year that are powerful enough to damage structures (5.5+ on Richter scale)
Studies of frequency and magnitude of past earthquakes show there is a good chance of a 7.0+ earthquake hitting San Francisco Bay before 2005
1906-San Francisco earthquake (7.8) which along with subsequent fires destroyed much of the city
Droughts at California
Caused by anticyclones (long lasting periods of high air pressure with sinking, dry air) dry sinking air=no rain
Drought caused by La Niña events (periods were the surface water is the eastern Pacific Ocean is cooler) this means less evaporation, so there is less precipitation
Another cause of drought is increased wind blowing westward from the desert areas that are east of California, eg. from Arizona -the dry air has no moisture to cause precipitation
Worst effect of drought in California is wildfires-dry vegetation is extremely flammable, so fires spread quickly over wide areas
Wildfires in Southern California in October 2007 killed 22 people and destroyed 1,300 homes
Tsunamis in California
Tsunami is a series of large waves that can flood coastal areas
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
Earthquake off the coast of Alaska in 1964 caused a tsunami to strike the coast of Northern California killing 12 people in crescent bay
Landslides in California
Occur on unstable ground that is steep-can be made unstable by coastal erosion or extreme weathering
Also triggered by earthquakes
Risk of landslide disasters in California is high because of buildings on and around steep slopes, as well as building on coastal land overlooking the ocean, eg. La Conchita
Volcanoes at California
Has not been a volcanic eruption since 1915 (Lassen Peak)
Volcanoes are being monitored though for potential eruptions eg. Lassen Peak and Mount Shasta
Wealthy/poor?
California is wealthy but parts of the population are vulnerable
How much of California’s population live within 50km of a fault line
Over 70%
What can lots of buildings on unstable land lead to
Soil liquefaction during earthquakes (ground becomes more like liquid) which damages buildings and increases the risk of landslides, major problem during the Loma Prieta earthquake (1989)
Where are vulnerable to tsunamis
Many buildings along the coastline
California is a wealthy state but…
There are very poor areas within it
Around 20% of residents in Los Angles live below the official poverty line-these people have the lowest capacity to cope when affected by a hazard
What does a massive economy mean
There are likely to be huge economic losses when a disaster occurs
