Transcript DP - quakes

2017 DYNAMIC PLANET:
EARTHQUAKES AND VOLCANOES
USE OF THIS POWERPOINT
PRESENTATION
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use.
You may freely burn and distribute as many copies of this
presentation as you wish.
Feel free to alter this presentation in any way you wish.
If you identify someone willing to coach this event, provide that
individual with a copy of this CD to introduce him/her to the
requirements of the event.
STUDENT DEVELOPED PPT.
PRESENTATIONS
 Encourage participants to develop their own PowerPoint
presentations as a way to prepare for this event.
 Suggest that participants first enter the event topics into their
PowerPoint presentations similar to an outline.
 As participants search the web for specific topics they will frequently
find information about other topics included in the event. They can
“fill-in” that information immediately.
 As participants discover better or more relevant information, they
may replace previous material with newly the newly discovered
material.
 Suggest that students “hold off” developing their resource pages
until they are well satisfied with their Power Points.
DYNAMIC PLANET: EVENT ROTATION
2009 & 2010: Earthquakes & Volcanoes
2011 & 2012: Earth’s Fresh Waters
2013 & 2014: Glaciers
2015 & 2016: Oceanography
2017 & 2018: Earthquakes & Volcanoes
1. DESCRIPTION
Students will use process skills to complete tasks related to
earthquakes and volcanoes.
A team of up to: 2
Approximate time: 50 minutes
2. EVENT PARAMETERS
Each team may bring four 8.5” x 11” two-sided page of notes
containing information in any print format from any source
 Can be laminated or in a sheet protector.
 Does not need to be double sided
 8 ‘sides’ is all you get
Each participant may also bring a “non-graphing” calculator.
THE COMPETITION
Participants will be presented with one or more tasks, many requiring
the use of process skills (i.e. observing, classifying, measuring,
inferring, predicting, communicating and using number relationships –
source: AAAS) for any of the following topics: Each addressed
separately.
COACHING TIPS AND HINTS: RESOURCES
Resources are to knowledge events as projects are to construction events.
Students develop their own resources; no hand-me-downs!
Participant-produced resources provide an oppor-tunity for coaches to
frequently and easily monitor participant progress.
Encourage continual revision of resources, i.e. after each level of
competition, when participants feel confident with their knowledge of
specific topics, etc.
COACHING TIPS AND HINTS: RESOURCES
Suggested items to include in student resources:
Definitions
Characteristics of the various types of volcanoes
Diagrams and illustrations
Characteristics of P, S and surface seismic waves
COACHING TIPS AND HINTS
With the growing complexity of the events, it is very difficult, if not
impossible, to coach all the events without assistance.
Should you find someone willing to coach the Earthquakes and
Volcanoes event, give him/her a copy of this PowerPoint presentation
to provide an overview of the event.
REPRESENTATIVE ACTIVITIES
Interpretation of charts, tables, diagrams (many of the diagrams
included in this presentation may be developed into an activity.
Locating the epicenter of a volcano
Patterns of volcanic and earthquake patterns around the world
(mapping)
Identification of volcanic features
Match volcanic features with popular examples, i.e. Devil’s Tower –
Volcanic Neck; Crater Lake – Caldera
COACHES’ RESOURCES
Information on all topics identified in the event rules may easily be
found on the web. Choice of “key words and phrases” are the keys to
success!
Be certain to caution participants to use only professional websites in
their search for information. These include the USGS, college sites, etc.
Middle/Junior/Senior High Earth Science Textbooks, and even
Introductory college textbooks
*The Game of Earth, NEW 2010 Edition
*The Theory of PLATE TECTONICS CD
*http://www.otherworlds-edu.com
A. WORLDWIDE DISTRIBUTION PATTERNS
OF EARTHQUAKES AND VOLCANOES
TYPES OF VOLCANOES: SHIELD
VOLCANOES
 Shield volcanoes are huge in
size.
 They are built up by many
layers of runny lava flows
spilling out of a central vent or
group of vents.
 The broad shaped, gentlysloping cone is formed from
basaltic lava which does not
pile up into steep mounds.
TYPES OF VOLCANOES:
STRATOVOLCANOES (COMPOSITE)
 Tall, conical volcanoes with
many layers (strata) of
hardened lava, tephra and
volcanic ash
 Characterized by steep profiles
and periodic, explosive
eruptions
 Lava tends to be viscous (very
thick)
 Common at subduction zones
where oceanic crust is drawn
under continental crust
TYPES OF VOLCANOES: CINDER CONES
 A cinder cone is a steep conical
hill of volcanic fragments that
accumulate around and
downwind from a volcanic vent.
 The rock fragments, often
called cinders or scoria, are
glassy and contain numerous
gas bubbles "frozen" into place
as magma exploded into the
air and then cooled quickly.
 Cinder cones range in size from
tens to hundreds of meters tall.
Cinder cones are made of
pyroclastic material.
CONTROLS ON EXPLOSIVITY:
POSSIBLE INTERPRETIVE ACTIVITY
SiO2
MAGMA
TEMPERATURE
VISCOSITY
GAS
ERUPTION STYLE
TYPE
(centigrade)
~50%
mafic
~1100
low
low
nonexplosive
~60%
intermediate
~1000
intermediate
intermediate
intermediate
~70%
felsic
~800
high
high
explosive
CONTENT
EXPLOSIVE VS. EFFUSIVE
TYPES OF VOLCANOES: ACTIVE, DORMANT,
EXTINCT (ACCORDING TO U.S.G.S.)
 An active volcano to volcanologists is a volcano that has shown
eruptive activity within recorded history.
 A dormant volcano is somewhere between active and extinct. A
dormant volcano is one that has not shown eruptive activity within
recorded history, but shows geologic evidence of activity within the
geologic recent past. An extinct volcano is one that is both inactive
and unlikely to erupt again in the future.
 An extinct volcano is a volcano that has not shown any historic
activity, is usually deeply eroded, and shows no signs of recent
activity.
VOLCANIC HAZARDS
Potential activity!
PRIMARY VOLCANIC HAZARDS:
PYROCLASTIC FLOWS
Pyroclastic flows are fast-moving, avalanche-like, ground-hugging
incandescent mixtures of hot volcanic debris, ash, and gases that can
travel at speeds in excess of 150 km per hour.
PRIMARY VOLCANIC HAZARDS: LAHARS
Lahars, also known as mud flows or debris flows, are slurries of muddy
debris and water caused by mixing of solid debris with water, melted
snow, or ice.
PRIMARY VOLCANIC HAZARDS: TEPHRA
Tephra (ash and coarser debris) is composed of
fragments of magma or rock blown apart by gas
expansion.
Tephra can cause roofs to collapse, endanger people
with respiratory problems, and damage machinery.
Tephra can clog machinery, severely damage aircraft,
cause respiratory problems, and short out power lines up
to hundreds of miles downwind of eruptions.
PRIMARY VOLCANIC HAZARDS: GASES
The concentrations of different volcanic gases can vary
considerably from one volcano to the next.
Water vapor is typically the most abundant volcanic gas,
followed by carbon dioxide and sulfur dioxide.
Other principal volcanic gases include hydrogen sulfide,
hydrogen chloride and hydrogen fluoride.
A large number of minor and trace gases are also found
in volcanic emissions, for example hydrogen, carbon
monoxide, halocarbons, organic compounds, and volatile
metal chlorides.
PRIMARY VOLCANIC HAZARDS: LAVA
FLOWS
Lava flows are generally not a threat to people because
generally lava will move slowly enough to allow people to
move away; thus they are more of a property threat.
PRIMARY VOLCANIC HAZARDS: FLOOD
BASALTS
 A flood basalt or trap basalt is
the result of a giant volcanic
eruption or series of eruptions
that coats large stretches of
land or the ocean floor with
basalt lava.
 Image: Moses Coulee showing
former, multiple flood basalt
flows of the Columbia River
Basalt Group.
SECONDARY VOLCANIC HAZARDS:
FLOODING
Drainage systems can become blocked by deposition of pyroclastic flows and lava
flows. Such blockage may create a temporary dam that could eventually fill with
water and fail resulting in floods downstream from the natural dam.
Volcanoes in cold climates can melt snow and glacial ice, rapidly releasing water into
the drainage system and possibly causing floods.
SECONDARY VOLCANIC HAZARDS: FAMINE
Several eruptions during the past century have caused a decline in the
average temperature at the Earth's surface of up to half a degrees
Fahrenheit for periods of one to three years.
Tephra falls can cause extensive crop damage and kill livestock which
may lead to famine.
TYPES OF EARTHQUAKES: SPREADING
CENTER
 An oceanic spreading ridge is
the fracture zone along the
ocean bottom where molten
mantle material comes to the
surface, thus creating new crust.
 This fracture can be seen
beneath the ocean as a line of
ridges that form as molten rock
reaches the ocean bottom and
solidifies
TYPES OF EARTHQUAKES: SUBDUCTION
ZONE
Major earthquakes may occur
along subduction zones.
The most recent sub-duction
zone type earth-quake occurred
in 1700.
Scientists believe, on average,
one subduction zone earthquake
occurs every 300-600 years.
TYPES OF EARTHQUAKES: TRANSFORM
FAULT
A transform fault is a special
variety of strike-slip fault that
accommo-dates relative
horizontal slip between other
tectonic elements, such as oceanic
crustal plates
TYPES OF EARTHQUAKES: INTRAPLATE
Intraplate seismic activity occurs
in the interior of a tectonic plate.
Intraplate earthquakes are rare
compared to earthquakes at
plate boundaries.
Very large intraplate
earthquakes can inflict very
heavy damage.
Distribution of seismicity associated with
the New Madrid Seismic Zone since
1974.
PRIMARY EARTHQUAKE HAZARDS: RAPID
GROUND SHAKING
Ground shaking, a principal cause of the partial or total collapse of
structures, is the vibration of the ground.
The first wave to reach the earth's surface, the P wave, causes a
building to vibrate.
The most damaging waves are shear waves, S waves, which travel
near the earth's surface and cause the earth to move at right angles
to the direction of the wave and structures to vibrate.
PRIMARY EARTHQUAKE HAZARDS: RAPID
Structural Damage
GROUND
SHAKING
Buckled roads and rail
tracks
SECONDARY EARTHQUAKE HAZARDS:
RAPID GROUND SHAKING
Landslides
Avalanches
SECONDARY EARTHQUAKE HAZARDS:
RAPID GROUND SHAKING
Alterations to Water Courses
Fire resulting from an earthquake
EARTHQUAKE HAZARDS: SHAKE MAP
 The Shake Map for the 1994
magnitude 6.7 Northridge, CA
earth-quake shows the
epicenter at the location of the
green star.
 The intensity of shaking created
by the earthquake is shown by
the different color gradients on
the map.
 The magnitude of the
earthquake is 6.7 no matter
where you are, but the
intensities vary by location.
STRUCTURAL ENGINEERING PRACTICES
Early alert capabilities in some cases will allow some systems to
automatically shut down before the strong shaking starts so that the
services and people using them will be safe. Such systems may include
elevators, utilities such as water and gas, and factory assembly lines.
VOLCANIC MONITORING: GEOLOGIC
HISTORY
The first thing scientists do is determine a volcano's eruption history. A
volcano is classified as active, dormant or extinct based upon when it
has last erupted.
Active volcanoes are in the process of erupting or show signs of
eruption in the very near future.
Dormant volcanoes are "sleeping." This means they are not erupting at
this time, but they have erupted in recorded history.
An extinct volcano has not erupted in recorded history and probably
will never erupt again.
VOLCANIC MONITORING: ASSOCIATED EARTHQUAKE
ACTIVITY
Each type of
ground-shaking
event usually
generates a unique
seismic "signature"
that can be
recognized and
identified as having
been "written" by a
specific event.
VOLCANIC MONITORING: MAGMA MOVEMENT
Earthquake activity beneath a volcano almost always increases before an eruption because
magma and volcanic gas must first force their way up through shallow underground
fractures and passageways. When magma and volcanic gases or fluids move, they will either
cause rocks to break or cracks to vibrate. When rocks break high-frequency earthquakes
are triggered. However, when cracks vibrate either low-frequency earthquakes or a
continuous shaking called volcanic tremor is triggered.
VOLCANIC MONITORING: SATELLITE DATA
Satellites can record infrared radiation where more heat or less heat
shows up as different colors on a screen. If a volcano is seeming to
become hotter, then an eruption may be coming soon.
VOLCANIC MONITORING: HAZARD MAPS
EARTHQUAKE MONITORING:
IDENTIFICATION OF FAULTLINES
New Madrid, Tennessee
San Andreas Faultline
EARTHQUAKE MONITORING: REMOTE
SEISMOGRAPH POSITIONING
 Scientists consider seismic activity
as it is registered on a
seismometer.
 A volcano will usually register
some small earthquakes as the
magma pushes its way up
through cracks and vents in rocks
as it makes its way to the surface
of the volcano.
 As a volcano gets closer to
erupting, the pressure builds up
in the earth under the volcano
and the earthquake activity
becomes more and more
frequent.
EARTHQUAKE MONITORING:
VS.analogDIGITAL
Below is a digital seismogram. The data
ThisANALOG
is an image of an
recording
of an earthquake. The relatively flat
lines are periods of quiescence and the
large and squiggly line is an earthquake.
is stored electronically, easy to access
and manipulate, and much more accurate
and detailed than the analog recordings.
EARTHQUAKE MONITORING: TILTMETER
When a volcano is about to
erupt, the earth may bulge or
swell up a bit.
Tiltmeters attached to the sides
of a volcano detect small
changes in the slope of a
volcano.
Installing a tiltmeter
EARTHQUAKE MONITORING: CHANGES IN
GROUNDWATER LEVELS
Hydrogeologic responses to large distant earthquakes have
important scientific implications with regard to our earth’s intricate
plumbing system.
The exact mechanism linking hydrogeologic changes and earthquakes
is not fully understood, but monitoring these changes improves our
insights into the responsible mechanisms, and may improve our
frustratingly imprecise ability to forecast the timing, magnitude, and
impact of earthquakes.
EARTHQUAKE MONITORING: OBSERVATIONS
OF STRANGE BEHAVIORS IN ANIMALS
 The cause of unusual animal behavior seconds before humans feel
an earthquake can be easily explain-ed. Very few humans notice
the smaller P wave that travels the fastest from the earthquake
source and arrives before the larger S wave. But many animals with
more keen senses are able to feel the P wave seconds before the S
wave arrives.
 If in fact there are precursors to a significant earthquake that we
have yet to learn about (such as ground tilting, groundwater
changes, electrical or magnetic field variations), indeed it’s possible
that some animals could sense these signals and connect the
perception with an impending earthquake.
VOLCANISM AT PLATE BOUNDARIES
Encyclopædia Britannica, Inc.
VOLCANISM OVER HOT SPOTS (OCEANIC
AND CONTINENTAL)
VOLCANISM: HYDROTHERMAL VENTS
 A hydrothermal vent is a geyser
on the seafloor.
 In some areas along the MidOcean Ridge, the gigantic plates
that form the Earth's crust are
moving apart, creating cracks
and crevices in the ocean floor.
 Seawater seeps into these
openings and is heated by the
molten rock, or magma, that lies
beneath the Earth's crust.
 As the water is heated, it rises
and seeks a path back out into
the ocean through an opening in
the seafloor.
PLATE BOUNDARIES: DIVERGENT PLATE
BOUNDARIES
Divergent plate boundaries are
locations where plates are
moving away from one another.
This occurs above rising
convection currents.
PLATE BOUNDARIES: OCEAN-OCEAN
CONVERGENCE
When two oceanic plates
converge one is usually
subducted under the other and in
the process a deep oceanic
trench is formed.
Oceanic-oceanic plate
convergence also results in the
formation of undersea volcanoes.
PLATE BOUNDARIES: OCEAN-CONTINENT
CONVERGENCE
 When an oceanic plate pushes
into and subducts under a
continental plate, the overriding
continental plate is lifted up
and a mountain range is
created.
 This type of convergent
boundary is similar to the
Andes or the Cascade Range in
North America.
PLATE BOUNDARIES: CONTINENT TO
CONTINENT CONVERGENCE
When two continents meet
head-on, neither is subducted
because the continental rocks are
relatively light and, like two
colliding icebergs, resist
downward motion. Instead, the
crust tends to buckle and be
pushed upward or sideways.
PLATE BOUNDARIES: DIVERGENT PLATE
BOUNDARIES - OCEANIC
When a divergent boundary occurs beneath oceanic lithosphere, the rising
convection current below lifts the lithosphere producing a mid-ocean ridge.
PLATE BOUNDARIES: DIVERGENT PLATE
BOUNDARIES - CONTINENTAL
When a divergent boundary occurs beneath a thick continental plate, the pull-apart
is not vigorous enough to create a clean, single break through the thick plate
material. Here the thick continental plate is arched upwards from the convection
current's lift, pulled thin by extensional forces, and fractured into a rift-shaped
structure.
PLATE BOUNDARIES: TRANSFORM PLATE
BOUNDARIES AT MID-OCEAN RIDGES
 Transform-Fault Boundaries are
where two plates are sliding
horizontally past one another.
These are also known as
transform boundaries or more
commonly as faults.
 Most transform faults are found
on the ocean floor. They
commonly offset active
spreading ridges, producing
zig-zag plate margins, and are
generally defined by shallow
earthquakes.
PLATE BOUNDARIES: RIFTING OF
CONTINENTAL PLATES
PLATE TECTONICS: SEAFLOOR SPREADING
Sea-floor spreading — In the early 1960s, Princeton geologist Harry Hess proposed
the hypothesis of sea-floor spreading, in which basaltic magma from the mantle rises to
create new ocean floor at mid-ocean ridges.
On each side of the ridge, sea floor moves from the ridge towards the deep-sea
trenches where it is subducted and recycled back into the mantle
GEOGRAPHICAL FEATURES ASSOCIATED
WITH PLATE TECTONICS
Mid-ocean ridges - Long
mountain chains on the sea-floor
that are elevated relative to the
surrounding ocean floor.
Trenches - Deep, arcuate
features, typically at the borders
of the oceans where oceanic
crust meets continental crust.
Trenches also occur where one
oceanic plate is diving below
another oceanic plate.
GEOGRAPHICAL FEATURES ASSOCIATED
WITH PLATE TECTONICS
 Fracture zones - Lie outboard of
transform faults where the fault ends
and so the same plate borders both
sides of the "fault." The fracture
zones record sites of past faulting
activity.
 Mid-Plate volcanoes - A broad term
to explain the many volcanoes found
far away from the spreading center,
or mid-ocean ridge.
 The volcanoes formed either due to
hot spots, or actually formed at the
spreading center but were carried
away along with the plate.
 Over time, the volcanoes stop
accreting new material and sink
below sea level as the oceanic crust
cools. Sea mounts are volcanoes
below sea level, and guyots are
volcanoes below sea level in which
the top has been planed off.
 Very old submerged volcanoes can
become abyssal hills.
GEOGRAPHICAL FEATURES ASSOCIATED
WITH PLATE TECTONICS
Island or volcanic arcs - Found adjacent to trenches. Site where the
rising magma from the subducting plate reaches the surface.
These chains are arcuate owing to the spherical geometery of the
Earth. Typically, these volcanoes have a mixed lithology between
continental and oceanic crust (andesite).
EVIDENCE OF SEA FLOOR SPREADING:
MAGNETIC REVERSALS
Magnetism on the ocean floor is
orderly, arranged in long strips.
The strips on the Atlantic ocean
floor, in particular, are parallel
to the mid-Atlantic ridge.
Their structure and distribution
are remarkably symmetric on
both sides.
EVIDENCE OF SEA FLOOR SPREADING: AGE OF
use the magnetic polarity of
SEA FLOOR AS OPPOSED TOScientists
CONTINENTS
the sea floor to determine the age.Very
little of the sea floor is older than 150
million years. This is because the oldest
sea floor is subducted under other
plates and replaces by new surfaces. The
tectonic plates are constantly in motion
and new surfaces are always being
created. This continual motion is
evidenced by the occurrence of
earthquakes and volcanoes.
EVIDENCE OF SEA FLOOR SPREADING:
FOSSIL EVIDENCE
DENSITY DIFFERENCES BETWEEN
CONTINENTAL AND OCEANIC PLATES
 Continental margin - Because of the density difference between
continental and oceanic crust, a particular geometry develops where
the two types of crust meet.
 Starting from the continent, there is first a broad, flat zone called
the "continental shelf."
 Then, near the end of continental crust, the angle increases and the
area is called the "continental slope."
 Further out, at the actual border between the two crusts, the slope
decreases, thus the "continental rise."
FAULTS: DIP-SLIP - NORMAL
 Normal faults happen in
areas where the rocks are
pulling apart (tensile forces)
so that the rocky crust of an
area is able to take up more
space.
 The rock on one side of the
fault is moved down relative
to the rock on the other side
of the fault.
 Normal faults will not make
an overhanging rock ledge.
 In a normal fault it is likely
that you could walk on an
exposed area of the fault.
FAULTS: DIP-SLIP - REVERSE
 Reverse faults happen in
areas where the rocks are
pushed together (compression
forces) so that the rocky crust
of an area must take up less
space.
 The rock on one side of the
fault is pushed up relative to
rock on the other side.
 In a reverse fault the exposed
area of the fault is often an
overhang. Thus you could not
walk on it.
 Thrust faults are a special
type of reverse fault. They
happen when the fault angle
is very low.
TRANSFORM (STRIKE-SLIP) FAULTS
 The movement along a
strike slip fault is
horizontal with the block
of rock on one side of the
fault moving in one
direction and the block of
rock along the other side
of the fault moving in the
other direction.
 Strike slip faults do not
make cliffs or fault scarps
because the blocks of
rock are not moving up or
down relative to each
other.
FAULTS: NORMAL AND REVERSE
 Normal – Normal faults form
when the hanging wall drops
down. The forces that create
normal faults are pulling the
sides apart (extensional).
 Reverse – Reverse faults form
when the hanging wall moves
up. Forces creating reverse
faults are compressional,
pushing the sides together.
HANGING WALL VS FOOTWALL
 Vertical faults are the
result of up or down
movement along a break
in the rocks. Actually, both
blocks may move up or
both blocks may drop, or
one might go up and one
might go down.
 It is the end result of the
movement that classifies
the relationship between
the blocks.
HANGING WALL VS FOOTWALL
The hanging wall block
is the one on the left
and the foot wall block
is the one on the right.
FAULTS: STRIKE-SLIP
Strike-slip faults have
walls that move
sideways, not up or
down.
The forces creating
these faults are lateral
or horizontal, carrying
the sides past each
other.
FAULTS: TRANSFORM
 Transform boundaries occur when
the two plates move past one
another. This is primarily a
function of equal density of the
plates; however, it also occurs
due to the direction of
movement. That is, if the direction
of movement of the two plates is
parallel but opposite, the plates
will neither subduct nor diverge.
 The boundary of movement is
called the transform fault. In
reality, it is rarely a singular
fault but rather a zone.
 Outlying the transform faults are
records of past tectonic activity
called "fracture zones."
CLIMATIC EFFECTS OF VOLCANIC EJECTA
Volcanic dust blasted into the atmosphere causes temporary cooling.
Volcanoes that release huge amounts of sulfur compounds affect the
climate more strongly than those that eject just dust. Combined with
atmospheric water, they form a haze of sulfuric acid that reflects a
great deal of sunlight which may cause global cooling for up to two
years. Much more at:
http://www.cotf.edu/ete/modules/volcanoes/vclimate.html
TSUNAMIS
TSUNAMIS: ORIGIN
Tsunamis can be generated by:
 Large Earthquakes (megathrust events such as Sumatra, Dec.
26, 2004)
 Underwater or near-surface volcanic eruptions (Krakatoa,
1883)
 Comet or asteroid impacts (evidence for tsunami deposits
from the Chicxulub impact 65 mya)
 Large landslides that extend into water (Lituya Bay, AK,
1958)
 Large undersea landslides (evidence for prehistoric undersea
landslides in Hawaii and off the east coast of North America)
TSUNAMIS: ORIGIN
TSUNAMIS: WAVE CHARACTERISTICS
Tsunami wave propagation characteristics – note that as water depth becomes smaller, waves slow down,
become shorter wavelength, and have larger amplitude.
TSUNAMIS: WARNING SYSTEM
 A tsunami warning system is a
system to detect tsunamis and
issue warnings to prevent loss
of life and property.
 It consists of two equally
important components: (1) a
network of sensors to detect
tsunamis and (2) a
communications infrastructure to
issue timely alarms to permit
evacuation of coastal areas.
Tsunami Monitoring Buoy:
Reports rises in the water
column and tsunami events
STAGES IN THE “LIFE” OF A TSUNAMIS :
INITIATION
 Near the source of sub-marine
earthquakes, the seafloor is
"permanently" uplifted and
down-dropped, pushing the
entire water column up and
down.
 The potential energy that
results from pushing water
above mean sea level is then
transferred to horizontal
propagation of the tsunami
wave (kinetic energy).
STAGES IN THE “LIFE” OF A TSUNAMIS:
SPLIT
Within several minutes of the
earthquake, the initial tsunami is
split into a tsunami that travels
out to the deep ocean (distant
tsunami) and another tsunami that
travels towards the nearby coast
(local tsunami).
STAGES IN THE “LIFE” OF A TSUNAMIS:
AMPLIFICATION
 Several things happen as the
local tsunami travels over the
continental slope. Most obvious
is that the amplitude increases.
In addition, the wavelength
decreases. This results in
steepening of the leading
wave--an important control of
wave runup at the coast.
STAGES IN THE “LIFE” OF A TSUNAMIS:
RUNUP
Tsunami runup occurs when a
peak in the tsunami wave travels
from the near-shore region onto
shore.
Runup is a measure-ment of the
height of the water onshore
observed above a reference sea
level.
SEISMIC WAVES: PRIMARY (P)
P-waves are the fastest type of
seismic wave. As P-waves travel,
the surrounding rock is
repeatedly compressed and then
stretched.
(Note: S and P waves are
classified as “body” waves.)
SEISMIC WAVES: SECONDARY (S)
S-waves arrive after P-waves
because they travel more slowly.
The rock is shifted up and down
or side to side as the wave
travels through it.
SEISMIC WAVES: SURFACE WAVES
 Rayleigh waves, also called
ground roll, travel like ocean
waves over the surface of the
Earth, moving the ground
surface up and down. They
cause most of the shaking at
the ground surface during an
earthquake.
 Love waves are fast and move
the ground from side to side.
SEISMIC WAVES:
PRIMARY (P)
The fastest wave, and
therefore the first to arrive
at a given location.
Also known as
compressional waves, the P
wave alternately
compresses and expands
material in the same
direction it is traveling.
USGS
Can
travel through all
layers of the Earth.
SEISMIC WAVES:
SECONDARY WAVES
(S)
The S wave is slower than
the P wave and arrives next,
shaking the ground up and
down and back and forth
perpendicular to the direction
it is traveling.
Also know as shear waves.
USGS
SEISMIC WAVES:
SURFACE WAVES
Surface waves follow the P
and S waves.
Also known as Rayleigh and
Love waves.
These waves travel along
the surface of the earth.
USGS
SEISMIC WAVES MEASUREMENT:
INTENSITY VS. MAGNITUDE
 Intensity scales measure the
amount of shaking at a
particular location.
 The intensity of an earthquake
will vary depending on where
you are.
 Magnitude scales, like the Richter
magnitude and moment
magnitude, measure the size of
the earthquake at its source.
 Magnitude does not depend on
where the measurement of the
earthquake is made.
 On the Richter scale, an increase
of one unit of magnitude (for
example, from 4.6 to 5.6)
represents a 10-fold increase in
wave amplitude on a
seismogram or approximately a
30-fold increase in the energy
released.
SEISMIC WAVES MEASUREMENT:
INTENSITY
I. Not felt except by a very few under especially favorable conditions.
II. Felt only by a few persons at rest, especially on upper floors of buildings.
III. Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake.
Standing motor cars may rock slightly. Vibrations similar to the passing of a truck. Duration estimated.
IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking
sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.
V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.
VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.
VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable
damage in poorly built or badly designed structures; some chimneys broken.
VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage
great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
IX. Damage considerable in specially designed structures; well-designed frame structures thrown out of plumb. Damage great in substantial
buildings, with partial collapse. Buildings shifted off foundations.
X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations. Rails bent.
XI. Few, if any (masonry) structures remain standing. Bridges destroyed. Rails bent greatly.
XII. Damage total. Lines of sight and level are distorted. Objects thrown into the air.
SEISMIC WAVES MEASUREMENT: FOCAL
DEPTH
 The vibrations produced by
earthquakes are detected,
recorded, and measured by
instruments call seismographs.
The zig-zag line made by a
seismograph, called a
"seismogram," reflects the
changing intensity of the
vibrations by responding to the
motion of the ground surface
beneath the instrument. From the
data expressed in seismograms,
scientists can determine the time,
the epicenter, the focal depth,
and the type of faulting of an
earthquake and can estimate
how much energy was released.
5. SCORING
Points will be awarded for the quality and accuracy of responses.
Ties will be broken by the accuracy and/or quality of answers to preselected questions.
7. NATIONAL SCIENCE EDUCATION
STANDARDS
Content Standard D. Structure of the Earth System; Earth’s history.
ADDITIONAL RESOURCES
 Volcanic Hazards & Prediction of Volcanic Eruptions:
http://www.tulane.edu/~sanelson/geol204/volhaz&pred.htm
 NSTA PowerPoint Presentation on Tsunamis
http://web.ics.purdue.edu/~braile/edumod/tsunami
/Tsunami!.ppt
Hydrothermal vents
http://www.ceoe.udel.edu/deepsea/level2/geology/vents.html
Plate boundaries
http://www.platetectonics.com/book/page_5.asp
ADDITIONAL RESOURCES
PowerPoint of Seafloor Spreading
http://www.sci.csuhayward.edu/~lstrayer/geol21
01/2101_Ch19_03.pdf
Windows to the Universe: Earthquakes
http://www.windows.ucar.edu/tour/link=/earth/g
eology/quake_1.html