13A.3 – Natural Hazards

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What are four main earthquake hazards in California?

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What are four main earthquake hazards in California? Tsunamis Seismic Shaking Liquefaction Landslides

Key Words

Hazard

Vocab Words

Natural Hazard Volcanic Field

What is a Natural Hazard?

An event that results from Earth processes and that can cause damage and endanger human life. Earthquakes, landslides, tsunamis,

shaking, liquefaction, volcanoes, mudflows and flooding in CA

Tornadoes, hurricanes, etc. in other states

California’s Earthquake Hazards

Hundreds of earthquakes each day in CA

Most are so weak they are generally not felt.

Earthquakes can lead to numerous other natural hazards Tsunamis, Seismic Shaking,

Liquefaction and Landslides.

Tsunamis

In the past 200 years, more than a dozen locally generated tsunamis have struck the CA coastline. Not all are locally such

as when a major earthquake in Alaska in 1964 produced a tsunami that struck Crescent City hours later and killed 11 people.

Seismic Shaking

The amount of shaking from one location to another varies.

The further from the epicenter the less shaking that will occur. Rock and soil

conditions also play a part.

Liquefaction

Liquefaction occurs when water-soaked soil turns to a thick, soupy liquid during an earthquake.

Landslides

When loose rock and soil on a slope moves resulting from an earthquake. Mostly on steep

slopes More likely after

fires or droughts since plants are damaged and they typically hold the soil in place.

California's Volcanic Hazards

Natural hazards that result from volcanic activity are volcanic ash, lava flows and volcanic gases.

The Cascade Range runs through CA, in northern CA. Most are dormant but can still erupt at

any given time. All composite cones and has the potential

to cause volcanic ash and lava flows.

California's Volcanic Hazards

Volcanic Field: An area that is covered by

volcanic rocks. Eastern and central parts of CA. Long Valley Caldera is an

example of a volcanic field. High concentrations of Carbon

Dioxide gases are currently leaking in this area; causing plants, animals and people to die. Especially Mammoth Mountain.

California's Storm Hazards

Two main storm-related hazards in CA are mudflows and flooding.

The dry conditions in southern CA make it very susceptible to mudflows and flooding, especially when precipitation is greater than normal.

Mudflows

Masses of very wet soil, and sometimes rock, that flows quickly downhill.

These are common in southern CA during and after severe rainfall.

Usually on a steep slope.

Flooding There are flash

floods in areas that have been in droughts.

Flooding, especially flash flooding is extremely dangerous because the water rises and moves rapidly.

Group Challenge Question

What factors are responsible for most of the floods in California?