Chp 16 Notes WWCC

8/14/2019 Chp 16 Notes WWCC

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Physical Geology Chp 16 Page 1 11/17/09

Physical Geology

Chapter 16

Earthquakes

Slide 2

An ___________________________ is a vibration in the earth created by the sudden

movement of the crust along a fault.

Slide 3

Tectonic forces put ___________________________ (force) on rocks.

As rocks are stressed they experience ___________________________

___________________________ is the movement (deformation) or rock by stress.

Eventually, rocks reach the point where they will no longer bend, and they

___________________________

Slide 4

The sudden snap in brittle rock creates ___________________________

___________________________ are the waves of energy produced by sudden

movement along a fault.

Slide 5

___________________________ is the current model of how the earthquakes are

created.___________________________ stress rocks.As

___________________________ is stressed it is ___________________________

Eventually ___________________________ ruptures along a fault.

A ___________________________ is a crack in Earth along which movement occurs.

Rocks that undergo strain,

Draw a diagram that shows the elastic rebound theory. Be sure to draw arrows that show

directions of stress.


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Slide 6

Earthquakes form along ___________________________ from different types of stress.

___________________________behavior of rock occurs near the surface of Earth where

temperatures and pressures are low. ___________________________ forces may be

___________________________ (tension), ___________________________, or

transform. Deep beneath Earths surface rocks have ductile behavior (plasticity).

Draw and label three diagrams showing how three different types of force creates faults.

Slide 7

List and describe three ways earthquakes may be generated.

1) __________________________________________________________________

2) _________________________________________________________________3) _________________________________________________________________

Slide 8

Focus is

________________________________________________________________________________________________________________________________________________

Epicenter is

_______________________________________________________________________

_________________________________________________________________________

Draw a diagram showing the focus and epicenter of an earthquake in and on Earth.

Slide 9

Name and define two types of seismic waves.

1) _________________________________________________________________


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_________________________________________________________________

_2) _________________________________________________________________

_________________________________________________________________

__

What type of waves are shown in the image on this slide? ____________________

Slide 10

Name two types of body waves.

a) ___________________________b) ___________________________

Slide 11

P-waves are also called ___________________________ or _____________________

cause particle motion that is ___________________________ to the direction of wave

travel. S-waves are also called ___________________________ or__________________________ and cause particle motion that is

___________________________ to the direction of wave travel.

Slide 12

P-waves cause the rock to be ___________________________ and

___________________________ as the wave moves through the rock. The part of the

wave where particles are squeezed together is called the _______________________ and

the part of the wave where particles are stretched apart is called ___________________.Name three things about P-waves.

a) _________________________________________________________________b) _________________________________________________________________

_

c) _________________________________________________________________Make a labeled drawing of a P-wave. Show the compression and rarefaction.

Slide 13

S-waves cause the rock to move ___________________________ to the direction thewave travels through the rock.


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Name Three things about S-waves.

a) _________________________________________________________________b) _________________________________________________________________

_

c) _________________________________________________________________Make a labeled drawing of a S-wave. Show the trough and crest.

Slide 14

___________________________waves are the slowest of all seismic waves. They are

the ___________________________ to arrive.

Name the two types of surface waves:

a) ___________________________b) ___________________________

___________________________waves cause a side-to-side motion of rock on the

surface of the earth. ___________________________waves cause particles to move in a

rolling motion (___________________________) as waves move over Earths surface.

Make a sketch showing a love wave.

Make a sketch showing a Rayleigh wave.

Slide 15___________________________ waves are the most destructive because they cause the

most ___________________________ and they ___________________________

longer.

Slide 16

___________________________ is the study of earthquakes. Mankind has been trying


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to predict ___________________________ for thousands of years. The

___________________________ have used animals and other devices in an attempt to

predict and measure earthquakes.

Slide 17

Seismic waves are studied with devices used to detect earthquakes called

___________________________. A seismometer that measures and records an

earthquake is called a ___________________________. The printed record of the

earthquake is called a ___________________________.

Slide 18

Make a labeled sketch showing how a seismograph works.

Describe how a seismograph works.

Slide 19

Explain how a seismograph is configured to measure vertical motion.


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Slide 20

Location of an earthquake is determined using a ___________________________ curveand results from at least ___________________________ recording stations. Since

seismic waves travel at ___________________________ speeds, they shouw up at

different intervals on the seismogram. The difference in time on the

___________________________ between P and S waves is then used on a

___________________________graph to determine the distance of the station from the

epicenter.

Slide 21

A ___________________________ is drawn on a map around the seismic station. The

___________________________ is somewhere along that circle. To pinpoint the

___________________________, the intersection of circles from three sites is needed.

Slide 22

Label The P-waves, S-waves, and surface waves on the seismogram below.


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What is the difference in time between the arrival time of the P-wave and S-wave?

_____________________________

Slide 23

The difference in arrival __________________________ between the P and S-waves on

the ___________________________ is then used on a ________________________ to

find the distance of the recording station from the ________________________ of the

earthquake.


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P and S-wave Travel Time Graph

Lets say the difference in arrival times of the p and s waves is 35 seconds, how far from

the epicenter is this recording station? _________________________

Slide 24

A _________________________ is then drawn around the seismic station on a map.

The radius of the circle is drawn to scale to represent the distance of the seismic station

from the _________________________. The epicenter is located somewhere along that


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_________________________. To pinpoint the epicenter, the intersection of circles

from _________________________ seismic stations is required.

Slide 25

Use the travel/time graph below and the map on the following page to find the epicenter

of an earthquake with the following P and S-wave arrival time differences.

1)San Francisco, CA station = 2 minutes and 12 seconds

2)Tulsa, OK station = 2 minutes and 30 seconds

3)Harvard, MA station = arrival of the P-wave 2:21:30 AM and arrival of the S-wave2:26:40 AM.

What is the distance of the following stations from the epicenter?1)San Francisco = __________________________

2)Tulsa = ____________________________

3)Harvard = _____________________________

Slide 27

Use a drawing compass, a ruler, and the scale stated on the map to plot the epicenter onthe map of North America.

Slide 28Name two ways that earthquake size is measured: ____________________________ and____________________________

____________________________ is the measure of the earthquakes effects of people

and man made structures.____________________________ is the measure of the energy released during an

earthquake.


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0 5000


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Slide 29-35

The Modified Mercalli Intensity Scale

I. People do not feel any Earth movement.II. A few people might notice movement if they are at rest and/or on the upper floors oftall buildings.

III. Many people indoors feel movement. Hanging objects swing back and forth. Peopleoutdoors might not realize that an earthquake is occurring.IV. Most people indoors feel movement. Hanging objects swing. Dishes, windows, anddoors rattle. The earthquake feels like a heavy truck hitting the walls. A few people outdoorsmay feel movement. Parked cars rock.V. Almost everyone feels movement. Sleeping people are awakened. Doors swing open

or close. Dishes are broken. Pictures on the wall move. Small objects move or are turnedover. Trees might shake. Liquids might spill out of open containers.VI. Everyone feels movement. People have trouble walking. Objects fall from shelves.

Pictures fall off walls. Furniture moves. Plaster in walls might crack. Trees and bushesshake . Damage is slight in poorly built buildings. No structural damage.VII. People have difficulty standing. Drivers feel their cars shaking. Some furniture

breaks. Loose bricks fall from buildings. Damage is slight to moderate in well-builtbuildings; considerable in poorly built buildings.VIII. Drivers have trouble steering. Houses that are not bolted down might shift on their

foundations. Tall structures such as towers and chimneys might twist and fall. Well-builtbuildings suffer slight damage. Poorly built structures suffer severe damage. Tree branchesbreak. Hillsides might crack if the ground is wet. Water levels in wells might change.IX. Well-built buildings suffer considerable damage. Houses that are not bolted downmove off their foundations. Some underground pipes are broken. The ground cracks.Reservoirs suffer serious damage.X. Most buildings and their foundations are destroyed. Some bridges are destroyed.

Dams are seriously damaged. Large landslides occur. Water is thrown on the banks ofcanals, rivers, lakes. The ground cracks in large areas. Railroad tracks are bent slightly.XI. Most buildings collapse. Some bridges are destroyed. Large cracks appear in the

ground. Underground pipelines are destroyed. Railroad tracks are badly bent.XII. Almost everything is destroyed. Objects are thrown into the air. The ground movesin waves or ripples. Large amounts of rock may move.

Slide 36

__________________________ is determined by measuring the waves from a

seismogram. The measurements are then compared to a scale called the

__________________________.

Slide 37.

The Richter scale magnitude is determined by measuring the__________________________ of the wave on the seismogram. This is then compared

to the __________________________ scale.


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Slide 38

________________________ is measure of the strength of an earthquake or strain

energy released by it, as determined by seismographic observations. This is

_________________ value originally defined by Charles Richter (1935). An increase of

one unit of magnitude (for example, from 4.6 to 5.6) represents an

________________________ increase in wave motion on a seismogram or

approximately a _____________________ increase in the energy released.

Slide 39

In other words, a magnitude 6.7 earthquake releases over ________________________

times (30 times 30) the energy of a 4.7 earthquake - or it takes about 900 magnitude 4.7

earthquakes to equal the energy released in a single 6.7 earthquake! There is no

beginning nor end to this scale. However, rock mechanics seems to preclude earthquakes

smaller than about ________________________ or larger than about

________________________.Slide 41

Another way to express magnitude is by _______________________.Moment

magnitude does not use the seismogram only for determination of the energy released

during the quake. It is determined from the _______________________ of the rock,

_______________________of the rupture, and the amount of

_______________________ along the fault. It is more complicated to determine, but is

a more reliable indicator of seismic energy release.

Slide 42

Where do we most likely find earthquakes around the world? ______________________

Name three seismically active ares of the earth.a)______________________________________________

b)______________________________________________ c)______________________________________________

Slide 43

Name six western states that are most prone to seismic activity.a) _______________________b) _______________________


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c) _______________________d) _______________________e) _______________________f) _______________________

Slide 44

When/where was the most powerful U.S. quake? _______________________ What

caused this quake? ______________________________________________

What Midwestern states could experience a powerful earthquake in the future?

_____________________________________________________________________

Slide 45

List 7 effects of earthquakes. Define terms and add notes where needed.

a) ____________________________________________________________________________________________________________________________________

b) __________________________________________________________________________________________________________________________________

__

c) __________________________________________________________________________________________________________________________________

__

d) __________________________________________________________________________________________________________________________________

____________________________________________________________________

e) ___________________________________________________________________________________________________________________________________________________________________________________________________

___

f) ___________________________________________________________________________________________________________________________________________________________________________________________________

___

g) ___________________________________________________________________________________________________________________________________________________________________________________________________

___

Slide 46-48

Before an earthquake occurs...

* Fasten shelves securely to walls, and place heavy objects on lower shelves.* Store breakable items in low, closed cabinets.


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* Hang items such as pictures and mirrors away from beds and anywhere people sit.* Brace hanging light fixtures.

* Repair known defective electrical wiring and gas connections.* Strap your water heater to studs in the wall and bolt it to the floor.

* Repair any large existing cracks in walls or foundations.

* Store poisons such as pesticides and herbicides, as well as flammable liquids, onbottoms shelves of latched cabinets.* Identify safe places in each room (under sturdy furniture, against inside walls,

away from glass).* Locate safe places outdoors (away from buildings, trees, electrical lines, and

bridges).* Teach family members how to turn off gas, electricity, and water.

* Teach children how to dial 911 in an emergency.* Have disaster supplies on hand (flashlight and extra batteries, battery operated

radio, first aid kit with manual, emergency food and drinking water, non electriccan opener, cash, sturdy shoes).

* Develop an emergency communications plan in case family members areseparated.

During an earthquake (indoors)...* Take cover beneath a sturdy piece of furniture or against an indoor wall away

from glass that might break.* Stay inside! The most dangerous thing you can do during an earthquake is to try

to leave.During an earthquake (outdoors)...

* Move into the open, away from buildings, street lights, and overhead utility wires.Stay there until the shaking stops.

During an earthquake (in a moving vehicle)...* Try to find a clear area away from buildings, trees, overpasses, and overhead

wires.* Stop quickly and stay in the vehicle.

* Once the shaking has stopped, proceed with caution. Bridges and ramps may havebeen damaged during the shaking.

Chp 16 Notes WWCC

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