Transcript Intensity

Earthquakes
Pancaking of buildings
Pancaking of buildings
Drop, cover, and hold on.
This depends on the size of the earthquake and the
observer's distance from it, because earthquake waves spread
out as they travel whilst becoming weaker.
A magnitude 6 earthquake several hundred kilometres away
can be often be felt for 30–40 seconds. The actual
duration of slip on the earthquake fault is usually quite brief —
just a few seconds for a magnitude 6 for example. This is
because the fault rupture spreads very quickly, so the whole
process of faulting is over very quickly.
During the very largest earthquakes, fault rupture can continue
for up to 5 minutes as the rupture spreads over a length of say
1000km. For these earthquakes very high levels of aftershocks
mean that continuous ground shaking can be felt for some
hours.
Here are plenty of things you can do right now to
prepare if you live in an earthquake-prone area.
1. Make sure each member of your family knows what to do
no matter where they
2. KNOW where your gas, electric and water main shutoffs
are and how to turn them off if there is a leak or electrical
short. Make sure older members of the family can shut off
utilities.
3. LOCATE your nearest fire and police stations and
emergency medical facility.
4. TALK to your neighbors--how could they help you, or you
them after an earthquake?
5. TAKE Red Cross First Aid and CPR Training Course.
6. MAKE your disaster supply kit. 7: BOLT bookcases, china
cabinets, tall furniture, file cabinets, etc. to wall studs
8. ASK AN ENGINEER about the seismic safety of your home
and/or business.
How do we protect
ourselves from
earthquakes?
1. In what area of our planet are
earthquakes most common?
Convergent boundary
volcanoes
Transform boundary
San Andreas fault
Pacific Ring of Fire
Earthquake prone
2. How is Earth affected by plate boundaries?
Divergent –
Tensional stress
Transform-Shear stress
Convergent Compressional stress
3. Which is the hanging wall and
which is the foot wall in a fault?
A is the
hanging
_______wall
while
B is the
foot wall.
_____
4. Describe the motion of the
foot wall and the hanging wall
in a normal fault.
Foot
wall
Hanging
wall
5. Describe the motion of the
foot wall and the hanging wall
in a reverse fault.
Hanging
wall
Foot
wall
Normal Fault
Reverse
Fault
Hanging
Movement Hanging
wall
of the
wall
goes down
crust
goes up
and foot
and foot
wall goes
wall goes
up.
down.
Epicenter
6. What is the
location within
Earth where
earthquake
begin?
Seismic waves
•Deep focus-weak earthquake
•Shallow focus- strong earthquake
Rocks break in
the focus
because of too
much stress!
7. Which state has the most frequent
earthquakes? Why?
Alaska registers the most earthquakes in a
given year, with California placing second.
California, however, has the most
damaging earthquakes because of its
greater population and extensive
infrastructure.
http://www.dailymail.co.uk/news/article-1366603/Earthquake-mapAmerica-make-think-again.html
http://www.washingtonstatesearch.com/United_States_maps/United_States_map.html
8. Describe the locations of nuclear power plants in the
United States? Any relation with the earthquake map?
Nuclear power plants in the United States
9. How do seismologists determine
the location of the EPICENTER?
They calculate the
distance and arrival
time of seismic waves
to determine the
epicenter.
10. Stress causes Strain. What are the
three types of strain?
Brittle strain
Ductile strain
Breaks.
Deformed-does not
return to original form.
Elastic strain
Returns to original
form or shape.
P-wave
S-wave
Surface wave
Primary Wave (fastest)
expands and contracts
Surface Wave
Rolling motion
Secondary Wave
right angle
13. What is the difference between
intensity and magnitude?
Magnitude measures the energy released
at the source of the earthquake. It is
measured with a seismograph based on the
amplitude.
Intensity is determined from effects
on people, human structures, and
the natural environment.
Magnitude = 1,2,3,4,5,6,7,8,9…
Intensity= I, II, III, IV, V, VI, VIII,
IX…
14. Which will have a higher intensity of
earthquake given the same magnitude?
Magnitude 7
in Alaska
California will have a higher
intensity because of higher
population density and massive
infrastructures.
Magnitude 7
in California
Magnitude does not change
wherever you are.
15. How is the intensity affected by
the distance from the epicenter?
Richter
Magnitude 9
in California
( Epicenter)
Intensity III
(Nevada)
Intensity II
(Utah)
Intensity
VIII
(California)
Intensity I
(Colorado)
http://earthquake.usgs.gov/earthquakes/map/
Seismic waves
Epicenter
Transform boundary
Shear Stress
http://www.washingtonstatesearch.com/United_States_maps/United_States_map.html
16.Why are seismic waves of an
earthquake more strongly felt at the
epicenter of an earthquake?
A.because the epicenter is directly the focus, the
place inside the earth where the earthquake
starts
B.because crustal plates rise and fall with the
ocean tides
C.because most faults converge at the epicenter
D.because millions of small movements of the
crust occur here
17. How are we affected by
earthquakes?
Liquefaction - soil turns to
mud due to severe shaking
of the ground.
Soil and rocks
Mud
Snow
Landslide
Mudslide
Avalanche
Landslide, mudslide, and avalanche all happen on a slope.
17. How are we affected by
earthquakes?
Tsunami
earthquake
Seismic
wave
Japan 2011
Water
receded
Indonesia, Sumatra 2004
18. What can we do protect ourselves against
the dangers of earthquakes?
Be aware!
Know where to go.
18. What can we do protect ourselves against
the dangers of earthquakes?
Secure
appliances,
cabinets,
and
furniture.
Know what
to do and
where to
go.
Be aware!
19. Why are aftershocks so dangerous?
Aftershocks are small tremors that happen
after the strong earthquake.
They are dangerous because they
have the power to crumble
buildings, roads, and bridges
already weakened by the initial
earthquake
While foreshocks comes
before a major earthquake.
a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
Epicenter ( p. 499 )
Fault ( p. 497 )
Focus ( p. 499 )
Primary wave ( p. 498 )
Secondary wave ( p. 498 )
Strain ( p. 496 )
Stress ( p. 495 )
Surface wave ( p. 498 )
Magnitude ( p. 505 )
Intensity (p. 506)
Open your textbook
to page 507 to learn
about earthquake
intensity.
Here are plenty of things you can do right now to prepare if you live in an earthquake-prone area.
1. Make sure each member of your family knows what to do no matter where they are when earthquakes occur:
o Establish a meeting place where you can all reunite afterward.
o Find out about earthquake plans developed by children's school or day care.
o Remember transportation may be disrupted, so keep some emergency supplies--food, liquids, and comfortable
shoes, for example--at work.
2. KNOW where your gas, electric and water main shutoffs are and how to turn them off if there is a leak or
electrical short. Make sure older members of the family can shut off utilities.
3. LOCATE your nearest fire and police stations and emergency medical facility.
4. TALK to your neighbors--how could they help you, or you them after an earthquake?
5. TAKE Red Cross First Aid and CPR Training Course.
6. MAKE your disaster supply kit. Beyond the usual flashlights, batteries and radios, include a first-aid kit; work
gloves; sturdy shoes or boots; a week’s supply of any presciption medications you or your family might need;
credit card and cash; personal identifcation; extra set of keys; matches in a waterproof container; map of your
area; phone numbers of family and other important people (doctors, veterinarians, etc.); copies of insurance
policies and other important documents; special needs equipment (diapers, baby formula, hearing aid batteries;
spare eyeglasses, etc.); three gallons of water per person; three-day supply of food per person; hand tools; a
portable ABC fire extinguisher; sanitation supplies for you and your family; entertainment (toys, books, coloring
books and crayons, playing cards)
7: BOLT bookcases, china cabinets, tall furniture, file cabinets, etc. to wall studs. Brace or anchor heavy
electronics and other heavy items. Secure items that might fall. Move heavy or fragile items to lower shelves.
Fasten drawers and cabinet doors with latches or locks. Brace overhead light fixtures. Strap your water heater to
wall studs and bolt down any gas appliances. Look for other non-structural steps you can take in your home and
workplace to reduce your chances for injury and loss.
8. ASK AN ENGINEER about the seismic safety of your home and/or business. It’s well known that unreinforced
masonry structures can fail quickly during earthquakes. An inspection by a structural engineer now can help you
decide if retrofitting will help your property withstand shaking.
http://earthquake.usgs.gov/learn/topics/megaqk_facts_fantasy.php