Disaster hotspot case studies- Califrnia coastline
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- Created on: 08-03-15 11:14
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- Disaster hotspot case studies- Califrnia coastline
- Location
- California is located on the south west coast of North America.
- 3rd biggest US state with an area of 163,696sqmi and biggest in terms of population with 38,802,500 residents
- The San Andreas fault (the conservative plate boundary between N. American plate and Pacific Plate) runs through California.
- Vunerability
- >70% of the population live within 50km of a fault line.
- An increasing population has led to buildings being developed on unstable land. This leads to liquefaction during EQs and can also increase the risk of landslides
- The coast is very developed meaning many people are at risk from Tsnamis
- 20% of residents live below the poverty line. These people have the lowest capacity to cope with disaster
- California is a highly developed area with state of the art technology that predicts disasters (e.g seismographs) as well as prevent them (e.g. building reinforcement, disaster training)
- It has a massive economy which means, combined with it's advanced prevention measures, that losses are mainly economic rather than human
- Earthquakes
- The San Andreas fault is a conservative plate boundary which runs through California making it very earthquake prone
- EQs occur when the parallel plates snag creating a build up of pressure which is suddenly released sending seismic waves in all directions.
- These EQs are usually shallow in California making them more destructive
- EQs occur when the parallel plates snag creating a build up of pressure which is suddenly released sending seismic waves in all directions.
- Facts
- These is a high chance that a 7.0+ magnitude EQ will hit San Francisco bay in the next 25 years
- 15-20 4.0+ magnitude EQs each year.
- More than 70% of California's population live within 50km of a fault line
- California has lots of building on unstable land which causes severe liquefaction
- Loma Prieta EQ- 1989
- A magnitude 7.1 struck in the Santa Cruz mountains 60 miles south of San Fransisco at 5:04 pm on 17 October 1989
- A magnitude 5.2 aftershock struck 37 mins after the main EQ
- 63 people were killed (mainly by a collapsed freeway); 13 750 were injured; 1081 homes were destroyed; 23 408 homes were damaged; just under 4000 businesses were destroyed or damaged; total cost US$6 billion
- The death toll was low due to the freeways being unusually clear due to the world series baseball game
- A magnitude 7.1 struck in the Santa Cruz mountains 60 miles south of San Fransisco at 5:04 pm on 17 October 1989
- Northridge EQ Los Angeles- 1994
- 57 killed; 1500 injured; 12 500 buildings damaged; 9000 homes and businesses without electricity; 20 000 without gas; 48 500 without water; damage to several freeways
- A magnitude 6.7 Eq struck the densely populated San Fernando VAlley at 4:31 on 17 Jan 1994
- 1000s of after =shocks of magnitude 4.0-5.0 occurred in the following weeks
- The San Andreas fault is a conservative plate boundary which runs through California making it very earthquake prone
- Volcanoes
- The last major volcanic activity was in 1915 when Lassen Peak erupted.
- Despite this many volcanoes are being monitored for activity such as Lassen Peak, Mount Shasta etc
- Tsnamis
- Caused by an EQ under the Pacific Ocean, a tsunami could devastate the many cities on the coast such as LA and San Francisco
- Crescent City Tsunami 1964
- On 28 March 1964 an underwater EQ of the coast of Alaska generated a tsunami which affected the entire Californian coastline. Crescent city was the worst affected with waves of up to 20ft.
- 11 people killed; $7,414,000 worth of damage; a further $1,500,000 along the rest of the Californian coast; fires broke out due to overturned gas truck;
- Droughts
- They occur during La Nina years in which the waters of the Eastern Pacific are cooler
- This results in less evaporation of surface water so less rainfall
- They are also caused by anticyclones (long lasting spells of high air pressure and sinking dry air)
- Also caused by an increase in dry, desert winds blowing form the east.
- Puts pressure on densely populated areas such as LA where there is a shortage of water.
- Wildfires
- Wildfires are one of the most dangerous effects of drought periods.
- Southern California wildfires 2007
- 14 people killed; 160 injured; 1,500 homes destroted; 3,900sqkm of land burned; approx. 1,000,000 people evacuated. There were also concerns about the effect of particulates on health
- Causes
- Dorught, hot weather and strong Santa Ana
- Sources include: damaged power lines, an over turned truck and even arsonists.
- A series of wildfires beginning 20th October 2007 swept across southern California. The fires were visible from space
- 17 of the fires were classified as major fire incidents
- As cities such as LA and San Francisco expand or people relocate into the hills fires become more hazardous to the population with more potential for damage.
- They occur during La Nina years in which the waters of the Eastern Pacific are cooler
- Landslides
- They are often caused by EQs during which sediment is shaken lose.
- The effect of this is magnified by wildfires which destroy plants that bind soil.
- Winter storms also erode soil causing landslides.
- Coastal erosion may also be a cause of landslides along the coast. Coastal climates are becoming more unpredictable increasing the risk of landslides
- The risk of landslide disaster is increased by building on steep, unstable land.
- La Conchita landslide 2005
- On the 10th Jan 2005 a major landslide (200,000 cubic meters) occurred in La Conchita on the site of a previous landslide (1995)
- 10 people were killed; 13 houses destroyed; 23 damaged
- The owners of the La Conchita Ranch (located at the top of the slope) were held partially accountable due to their inadequate drainage systems
- They are often caused by EQs during which sediment is shaken lose.
- Location
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