CASE STUDY - California: A Multiple Hazard Environment

Which state in the USA is the richest?

California

Where is California located?

The nothern hemisphere in the continent of North America, and is a state on the Pacific coast of the south west USA

What is the population of California?

39.2 million

What is the population of Los Angeles?

18 million

What are the different hazards found in California?

• Earthquakes

• River floods

• Mudslides

• Coastal flooding

• Landslides

• Smog

• Water shortages (drought)

• Wildfires

The future of California:

Increasing population

Increases pollution, use of water, and puts people closer to risks such as fires and floods

The future of California:

Climate change

Worsens floods, storms, droughts and fires

The future of California:

Overdue tectonic activity

Increases scale of damage from landslides/mudslides

Causes of earthquakes in California

• A network of active fault lines (including San Andreas fault) underlies the region

• California sits on a conservative plate boundary

Example of an earthquake in California (deaths, cost of damage, magnitude)

The Northridge earthquake in 1994, killed 57 and caused $13-14bn of damage (magnitude 6.7)

Impacts of earthquakes in California

FOR REFERENCE:

• Deaths and causes

• Damage costs

• Water

• Electricity

• Secondary damages

• Over 60 people killed through explosions from broken gas pipes, landslides and the collapse of apartment blocks, houses and highways

• People became trapped in high rise buildings

• $30 million in property damage

• 200,000 left without water

• 3 million left with no electricity supply

• Secondary damages such as landslips, blocked roads

Responses to earthquakes in California

FOR REFERENCE:

• Companies

• Public highways

• Gas, water, electricity

• Large companies sitied in the centre of the city have generally found the money to make high rise buildings that can resist the movements and vibrations created by the earthquake

• Many public highways have also had to be strengthened or modified

• The gas, water and electricity companies have put in place a number of high-tech measures to try and reduce the damage to their supplies in an earthquake, but these have been at quite some expense to the consumer

What secondary hazards are created by earthquakes in California?

Landslides. potentially tsunamis

Causes of wildfires in California

• Climate

• Human causes

• L.A. has a Mediterranean type climate. It has drought caused by anticyclones. Dry sinking air means no rain

• Drought can also be caused by La Nina events

• A careless spark from cigarettes or match, or an electrical storm can start a brush fire during the late summer, when vegetation is very dry

What winds are found in California and what makes them so dangerous?

Santa Ana winds drive wildfires up and down the canyons and hills

Impacts of wildfires in California

• Vegetation is burnt and destroyed

• Many houses are destroyed

• Potential injuries and fatalities, pet losses

Why is urban sprawl increasing wildfire risk?

Urban sprawl pushes people to rural areas (low density residential development in the hills has increased the fire risk)

Causes of landslides and mudflows in California

• Landlsides and mudflows are a result of earthquakes, heavy rain, deforestation and fires, or over urbanisation

• They can even be caused by water seepage from domestic supply and usage

Impacts of landslides and mudflows in California

• Landslides and mudflows can destroy houses, as hillsides may collapse and if people are in the vicinity, the speed of the event may catch them unaware resulting in injury or even death

• Most people feel that they have little control over the occurrence of landslides, the majority of the responsibility falls on the city government and building companies

What has the response of the city government been?

To restrict development on steep slopes and other risky areas

What is smog?

Smoke + fog

What are the causes of smog in California?

• California (especially L.A.) has a rising population

• Pollution from vehicles, industry and power stations becomes trapped in the lower atmosphere due to the occurrence of a temperature inversion

What is temperature inversion?

A phenomenon which occurs during the summer months, prevents mixing of the upper and lower atmosphere, trapping the pollutants

What do the pollutants consist of?

• Nitrogen oxides

• Ozone

• Sulfur dioxide

• Hydrocarbons

• Various other gases

Impacts of smog in California

The pollution exacerbates breathing problems such as asthma and causes a huge increase in the number of breathing associated admissions and casualty and may even result in death in very sensitive or unwell people

Why is it very difficult to reduce the pollution levels in California?

Most people are unwilling to give up their car

Responses to smog in California

• The response of the city government is to impose restrictions on emissions by industry and cars, but many of the large companies fear impact on their profits and therefore prevent any effective cuts from being made

• Implement vehicle checks where cars have to have their tailpipe emission tests

• Improve public transport

• Environmental laws

Name an example of an environmental law

The USA 1963 Clean Air Act

Causes of river flooding in California

• Heavy rain and storms may cause rivers to overflow

• Deforestation, brush fires and urbanisation have tended to exacerbate the problem by reducing interception and percolation increasing surface run-off

Impacts of river flooding in California

• Houses and any other structures on the flood plains are at most risk and can be carried all the way out to sea

• Loss of life is not usually high, although 8 people were killed in 1992

• The problem is that people want to live on floodplains, where risk is highest as the land is economically very valuable

Responses to river flooding in California

• Channel straightening (water flows quicker)

• A number of large dams have been built to try and hold back the water, but only limited success has resulted

• Many stretches of river have been enclosed in reinforced levees

• Water storage areas

Causes of coastal flooding in California

• High tide causes hills/cliffs to erode

• Long Beach area is a flood hazard zone due to coastal subsidence linked with oil extraction

• Storm surges from tropical storms, increasing with climate change

Impacts of coastal flooding in California

Cliffs erode and collapse, puts structures built on these cliffs at risk from collapsing with the cliffs

Responses to coastal flooding in California

• Sea defenses e.g. hard and soft engineering (i.e. gabions, sea walls, groynes etc.)

• Land use planning

• Managed retreat

• Relocation of homes/farms at the areas of risk

Managing multiple hazards in California:

Earthquakes

• Protect buildings (earthquake-proof) e.g. Trans-America Pyramid

• Earthquake drills

• Seismometers

• “drop, cover and hold on”

Managing multiple hazards in California:

River floods and mudslides

• Build dams on tributaries in the mountains to contain the water near sources and manage flow

• Develop a water storage area that could take water in a time of flood, e.g. use a retaining dam across the valley of the Rio Hondo and San Gabriel

• Construct debris dams high up to prevent large amounts of river load from blocking bridges downstream and causing even more severe flooding

• Channelise the majority of the river system to enable quicker and more efficient flow, e.g. straighten rivers and pave bed and banks with concrete

• CCPN (California’s Coastal Protection Network) is an organisation to protect the coastline from sea level rise, housing developments and industrial development

Managing multiple hazards in California:

Coastal flooding and landslides

• Sea defenses

• Land use planning

• Managed retreat

• Relocation

Managing multiple hazards in California:

Smog

• Vehicle checks are carried out to make sure they comply with emissions limits (cars in California have to have tailpipe emissions tests)

• Improve public transport

• Environmental laws (e.g. USA 1963 Clean Air Act)

• The South Coast Air Quality Management District has a 15-year smog reduction plan involving cash incentives for cleaner vehicles; this may not go ahead with Trump administration moves to remove environmental laws

Managing multiple hazards in California:

Water shortages (droughts)

• Dams and reservoirs

• Water storage areas

• Education - careful usage

• Hosepipe bans

Managing multiple hazards in California:

Wildfires

• Educate the public about fire hazards (e.g. Smokey the Bear) and require people to buy permits before doing any large scale burning, e.g. on farmland

• Well trained emergency services

• Firebreaks

Managing multiple hazards in California:

All hazards

• Take out insurance against damage to your home, office or business

• FEMA (Fedaral Emergency Management Agency) uses a number of grants to help prepare for and respond to a variety of disasters