Transcript 13A.3 – Natural Hazards

13A.3 – Natural
Hazards
Do Now

What are four main earthquake
hazards in California?
Do Now

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

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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

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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:
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
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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.
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Mudflows
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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?