Signature Assignment Course GEOL 1303: Physical Geology

Assignment Title Earthquake Assignment

Assignment ID (to be assigned)

Outcomes/Rubrics to be Assessed by the Assignment

o Communication o Critical Thinking o Empirical and Quantitative Reasoning

Assignment Description

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AssignmentDesignWorksheet:CriticalThinkingGEOL1303

EarthquakeAssignment

Course

AssignmentTitle

AssignmentID (tobeassigned)

Criterion Design(Howdoestheassignmentaskstudentstoperforminthemannerexpectedbythecriterion?)

ExplanationofIssues

Thesuccessfulstudentwillstate,clarify,anddescribetherelationshipbetweenplatetectonicsandearthquakedistributionintheir1-pagepaper.

Evidence Studentsaretooffertheirownanalysisbasedontheresultsofplottingmajorearthquakesandhowtheseearthquakesarerelatedtoplatetectonics.Studentsaredirectedtocite3resourcestosupporttheirviewpointwhenanalyzingtherelationshipbetweenplatetectonicsandearthquakedistribution.Inaddition,studentsaretouseFigure1AmplificationofShakingtoanalyze/interprettherelationshipbetweentheinfluenceofunderlyingsoilandrock,totheamplificationofseismicwaves.

InfluenceofContextandAssumptions

Studentsareaskedtoidentifyrelatedconditionsthatinfluencedthehighdeathtollduringthe2010Haitiearthquake.ThemajorityofHaiti’spopulationhasalowsocioeconomicstatus,includingpoorlivingconditionsandpoorhousing.Theseconditions,alongwithlackofhealthservices,elevatedthedeathtoll.Studentsaretoidentifyhowrelationshipsbetweencultural,political,andsocietalstatuswithinaregioncaninfluencethepotentialdamagebyanearthquake.

Student’sPosition Withintheanalysisoftherelationshipbetweenplatetectonicsandearthquakedistribution,successfulstudentswillacknowledgedifferentsides,perspectives,andcomplexitiespertainingtowhysomeearthquakeshadmorefatalitiesthanothers.Thesefactorsextendbeyondthegeologicconstraintsandincludeadditionalfactors(i.e.buildingcodes,spreadofdisease,etc.).

ConclusionsandRelatedOutcomes

Conclusionsandoutcomesreachedbystudentsarebasedontheevidenceobtainedbythesumofallthedata,i.e.graphs,diagrams,plots,andseismogramreadings.Studentsaretorelatethisinformationtoidentifytheimplicationsofsoiltype,platetectonics,andbuildingintegritytothelevelofdestructionbyseismicwaves.

AssignmentDesignWorksheet:WrittenCommunication

GEOL1303:PhysicalGeology

Earthquake&SeismicActivityLab

Course

AssignmentTitle

AssignmentID (tobeassigned)

Criterion Design(Howdoestheassignmentaskstudentstoperforminthemannerexpectedbythecriterion?)

ContextofandPurposeforWriting

Studentsareaskedtowriteapaperbasedontheirawarenessandknowledgeofearthquakes,soiltype,andplatetectonics.Inaddition,studentsareaskedtoidentifycontributingfactorsoutsideofthescopeofearthquakesandplatetectonics,totheimpendingdeathsanddestructioncausedbyearthquakes.

ContentDevelopment

Thisassignmentdirectsstudentstoinvestigatetherelationshipbetweenplatetectonicsandearthquakedistribution.Thisistheoverarchingtopicofthewrittencomponentoftheassignment,soasuccessfulstudentshouldaddressitthroughouttheirpaper.

GenreandDisciplinaryConventions

Studentsareexpectedtoproduceaone-pagepaper;thesuccessfulstudentwillcompletethistaskinawaythatisconsistentwithbasic,commonpractices.

SourcesandEvidence

Studentsareaskedtocitethree(3)resourcestosupporttheirviewpointswhenanalyzingtherelationshipbetweenplatetectonicsandearthquakedistribution.Weexpectthatthesuccessfulstudentwilluserelevantexamplesandreferencematerialthroughouttheirresponse.

ControlofSyntaxandMechanics

Studentsareexpectedtouseclearlanguagethatreadersareabletounderstandeasilyintheirone-pageresponse.

ReadabilityofVisualElements

Studentswillconstructaonepagepagerwiththefollowingvisualparameters:1-inchmargins,12pointfont,and1.5linespacing.

Relevance,Accuracy,andIntegrationofVisualElements

Studentswillbeinstructedtointegratethevisualelementsparametersintoawell-constructedpaperwithproperheadings,paragraphs,sentencestructure,andgrammar.Instructorsmayshowexamplesofwellwrittenscientificpapersforstudentstouseasatemplate.

AssignmentDesignWorksheet:Empirical&QuantitativeReasoning(EQR)

GEOL1303

EarthquakeAssignment

Course

AssignmentTitle

AssignmentID (tobeassigned)

Criterion Design(Howdoestheassignmentaskstudentstoperforminthemannerexpectedbythecriterion?)

Interpretation Studentsaregiventhreeseismogramsandareaskedtocalculatethedistanceoftheearthquake’sepicenterfromtheseismograph.Studentsthenplotthedatausingthemethodoftriangulationtovalidatetheiranswers.Ifstudentsdidthefirstpartcorrectly,thetriangulationstepwillyieldapreciseoverlapshowingtheepicenter.Basedontheresults,studentsareaskedtoexplaintherelationshipbetweenPandS-wavearrivaltimesandthedistanceoftherecordingstationfromtheepicenter.

Representation StudentsareaskedtomeasurethetimeintervalbetweenPandS-wavesfromthreerecordingstationsinordertoidentifythestation’sdistancefromtheepicenter.Inaddition,studentswillcalculatethelag-timebetweenPandS-wavearrivaltimestodeterminetheexacttimeintervalanddistancefromtheepicenter.

CalculationorTransformation

Studentsareexpectedtocalculatethedistanceoftheseismographfromtheepicenterfromthe“P-SInterval”thattheydeterminebyreadingadiagram(the“Time-Travelgraphprovidedbyyourinstructor”).

Application/Analysis Studentsdrawbasicconclusionsandmakestrateforwardjudgementsbyanalyzingtherelationshipbetweenplatetectonicsandearthquakedistribution.Thisexerciserequiresstudentstothinkindependentlyandtomakeoneormoredecisions;studentsarenotdeliveringadefinitiveanswer.

Assumptions Studentswillbaseconclusionsandassumptionsontheresultoftheirdata.Studentsareaskedtodescribe/explaintherelationshipbetweenPandS-wavearrivaltimesandthedistanceoftherecordingstationfromtheepicenter.

Communication Whenstudentsanalyzetherelationshipbetweenplatetectonicsandearthquakedistribution,theyaredirectedtousequantitativeinformation(fatalities)aspartoftheirargumentandprovidenumericalsupportforthatargument.

1 EARTHQUAKE & SEISMIC ACTIVITY LAB This lab is for educational purposes only at San Jacinto College.

Posting or linking for public use is strictly prohibited.

• Identify P, S, and surface waves on a simple seismogram• Locate the epicenter of an earthquake using seismograms and travel-time curves• Analyze how the geology of a region can affect the amplification of seismic waves• Critically assess the relationship between plate tectonics and earthquake distribution

Earthquakes are shaking and vibrations of the ground that are produced when rocks rupture along a fault releasing stored up elastic strain energy as heat and seismic waves. They can also be generated by sudden movements along plate boundaries and by relocation of magma under a volcano. Earthquakes produce three types of seismic waves: P, S, and surface waves. Seismic waves are elastic waves that originate at the focus, the underground origin of the earthquake. The epicenter is the point on the Earth’s surface directly above the focus. Seismic waves travel in all directions through the body of the Earth and along Earth’s surface. The waves are recorded by earthquake – detecting instruments called seismographs.

Most earthquake damage is caused by ground shaking. The damage varies from region to region depending on three main factors:

• 1) Proximity to the source of the earthquake• 2) Earthquake magnitude• 3) Influence of the underlying soil on the amplification of shear waves (S-waves)

FIGURE 1 Amplification of Shaking

Critical Thinking Analyze Figure 1 to answer the following questions: 1. Shaking is stronger when the shear wave velocity is ________________. (slower or faster)2. What kind of sediment significantly amplifies shear waves? _______________________________________3. If your house was built on bedrock/igneous rock, would you expect significant damage during a large

earthquake? _______ (yes or no) Why? ____________________________________________________4. Much of the San Francisco Bay Area sits atop sands, sandstones, mudstones, and limestone.

a) Is San Francisco in an earthquake prone area?______________.b) If the San Francisco Bay Area were to experience a significant earthquake, what kind of damage would

you expect?

KEY Vs – velocity of shear wave (S) Vs >1500 m/sec – does not contribute greatly to shaking amplification Vs 750-350 m/sec Vs 350-200 m/sec - significant amplification Vs 200 m/sec – strongest amplification in bay muds and artificial fill

Bedrock/igneous rock Sedimentary rocks Poorly consolidated sediment Well consolidated Sand/gravel/silts/mud/artificial fill

Vs >1500 m/sec Vs 750-350 m/sec Vs 350-200 m/sec

Copyright 2008 Pearson

Objectives:

2 LOCATING THE EPICENTER OF AN EARTHQUAKE

Empirical and QuantativeI. Using a SeismogramEarthquakes produce seismic waves that spread out from the focus and epicenter in all directions. The wavestravel at different speeds. A seismograph detects the arrival times of the seismic waves and produces aseismogram, a record of the wave motion at a recording station.To locate the epicenter of an earthquake, we use two body waves, P and S, which are generated at the focus andtravel through the Earth’s interior.

• P-waves (primary) travel fastest and arrive at the recording station first.• S-waves (secondary or shear) travel slower and arrive after the P-waves.• The seismograph also records surface waves, which travel along Earth’s exterior and arrive after the

P and S-waves. These waves are not used to locate an epicenter.

The P-S time interval is used to determine the distance to an earthquake.

• Start with the measured time interval between the arrival of theP and S-waves. Example: Use 3 minutes from above seismogram

• Time in minutes side of graph – measure 3 minute spacing ona piece of scratch paper

• Then find the 3 minute vertical spacing on the graph betweenthe P and S curves

• Read the distance at the bottomWhat is the distance to the earthquake’s focus? __________ miles

Work the problems below using the Travel-Time graph provided by your instructor.

1. P-S time interval 2 min 30 sec = _____________ miles2. P-S time interval 3 min 45 sec = _____________ miles3. P-S time interval 5 min 45 sec = _____________ miles

Figure 2 Parts of a Seismogram

P-S time interval

TimeCopyright McGraw-Hill

Seismogram Practice Problem: What is the P-S time interval in Fig. 2? __________ minutes

II. Using Travel-Time Graphs for P and S wavesSeismograms record the arrival times of the P and S-waves. We measure the time between the P and S-wavearrivals and then calculate the distance to the focus using travel-time graphs for the P and S-waves.

Figure 3 Travel-Time Graph Copyright McGraw-Hill

In addition to using the measured time interval between P and S-waves, time intervals can be calculated based on the lag-time by subtracting the P-wave arrival time from the S-wave arrival time. Calculate the lag-time by using P and S-wave arrival times: P wave arrival time 10:52:45 S wave arrival time 10:55:48 Time interval:_________________ Distance from the focus: __________ miles.

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• Use the 3 seismograms below, Time-Travel graph provided by your instructor and the map on page 4for your triangulation (Fig. 5)

EARTHQUAKE DATA TABLE Houston, TX Los Angeles, CA St. Louis, MO

P-S Interval(in minutes)Distance from Earthquake in Miles

Figure 4

Seismograph Station C: St. Louis, MO

Seismograph Station A: Houston, TX

Empirical and Quantitative cont.

III. Using Triangulation to Locate the Epicenter of an EarthquakeScientists use triangulation to find the epicenter of an earthquake on a map. Three seismograph stations are used.A circle is drawn around each station, where the radius of each is the distance from the seismograph to theearthquake. The intersection of the three circles at one point is the epicenter.

Seismograph Station B: Los Angeles, CA

TIME

4

Figure 5 – Map for Triangulation • See Data Table on page 3 – use Distance from Earthquake in Miles data• Take compass and measure distance on scale at bottom of this map.• Use compass to draw a circle around each seismograph station (A, B, and C).• Epicenter – intersection of 3 circles

Where is the epicenter of this earthquake?_________________

Based on your results, explain the relationship between P-wave and S-wave arrival times and the distance ofthe recording station from the epicenter:_______________________________________________________________________________________________________________________________________________________________________________

5

Locate the following earthquakes on the plate tectonic map on the following page. (Fig 6) On the map, draw an arrow with the earthquake number at each of the following locations.

1. The Central Mexico earthquake caused major damage to buildings in Mexico City, which resultedin loss of life. What geologic factor contributed to the increased amplification of seismic waveswithin Mexico City?

2. With the exception of Haiti, what type of plate boundary generates the largest magnitudeearthquakes? Think about where earthquakes #1 and #2 occurred and what geologic hazard wasresponsible for the high death toll.

3. The earthquake in Haiti was a magnitude 7.0 and yet the death toll was greater than a couple ofthose with a higher magnitude. What could be a possible explanation?

4. Analyze the North American plate. Its eastern side has several large faults that formed during thebreakup of Pangaea. Why is the eastern side of the plate not an active earthquake region?

Critical Thinking & Written Communication (To Be Done Individually)

Analyzing the relationship between plate tectonics and earthquake distribution

Analyze your plotted earthquake data and write a one page paper explaining the relationship between plate tectonics, specifically the type of plate boundary, and the occurrence of major earthquakes. Also, include related implications regarding geologic hazards associated with some earthquakes based on where the rupture/movement occurs, (land or ocean). Paper must be typed with 1-inch margins, and 12 point font with 1.5 line spacing. In addition, cite 3 resources to backup your viewpoint.

The following are some questions to consider when writing your paper:

Figure 6

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