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A quarterly publication for educators and the pul)lic-contemporary geological topics, issues and events

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"[’he worm watches as the comet collides with Jupiter.

This Issue:Earth Br/efs--Astronomers jump atchance to watch comet strike Jupiter

Have you ever wondered... Why Earth-quakes Occur?

What if ...New Mexico had a largeearthquake?

Glossary for UnderstandingEarthquakes

Tasty Quake----a recipe for earthquakewaves

Current topics in Earth Science---highLttes

Spring 1994

New Mexico Bureauof

Mines and MineralResources

(NMBM&MR)

Earth BriefsWorld Watches as CometCollides with Jupiterthis SummerDave FinleyPublic Information Ofj~cerNational Radio Astronomy C)b’servato~

Collision is one of the mostcommon astrogeological processes inour solar system. Landscapes coveredby craters, the telltale marks ofcollisions, have been photographed byspacecraft throughout the solar systemfrom Mercury, the closest planet to thesun, to the moons of distant Neptune.

, Although collision is a common "process in the solar system, we will getour first chance to observe such an eventthis summer. Astronomers last yeardiscovered a comet that Will strike thegiant planet Jupiter this Jul~ ThE comet,called Shoemaker-Levy 9 after itsdi~overers, was found on March.25,1993. As astronomers tracked the cometthey learned that it is orbiting Jupiteritself, unlike most comets, which orbitthe Sun.

In addition, calculations showed thatthe comet had passed very close toJupiter on July 8,1992--so close, in fact,that Jupiter’s powerful gravity hadbroken it into pieces. During thecomet’s next approach to Jupiter thissummer, its luck will run out and itspieces will slam into tl~e planet.Between July 16 and 22, at least 21comet fragments will hit Jupiter.

Unfortunately, the impacts of the.comet fragments are now predicted tooccur on the side of Jupiter facing awayfrom Earth. However, most of their/ipact sites will rotate into view soonafter the impact. Don’t expect to seenew craters, though--remember,Jupiter is a "gas giant" planet whosesolid core (if it.has one) is buried deep

Lite Geology, Spring 1994

(continued from front page)

ut~der thousands of miles of thick gasand liquid.

The impacts should be spectacular.Each comet fragment, with a maximumdiameter of about 500 yards, will hitJupiter at a speed of about 130,000m.p.h. The fragments are expected todisintegrate 60 to 70 miles below thetops of Jupiter’s visible clouds,releasing kinetic energy equivalent to200,000 megatons of TNT. That’s morethan 10 million times the energy of theHiroshima bomb. ’

This tremendous release of energy isexpected to produce a fireball that willrise 60 miles above Jupiter’s cloudtopsand send giant shock waves through theplanet’s atmosphere. Scientists hope touse theseeffects to learn about thecomposition of Jupiter’s clouds andthestructure of its atmosphere. In addition,the comet collision is expected to havepossibly dramatic effects on the radioemission from Jupiter.

Amateur astronomers hope that thefireballs from the fragment impactsmay be visible in small telescopes asflashes reflected off Jupiter’s fourlargest moons. Ra~dio enthusiasts willmonitor Jupiter!s shortwave "noise" tosee if they can hear any changes whenthe comet pieces hit.

Scientists from New Mexico’s stateuniversities, astronomical observatoriesand natienal laboratories are deeplyinvolved in the myriad of studies ofthis event. Some are running computersimulations to refine predictions of theimpact effects. Others will be using awide variety of instruments, dn Earthand in space, to observe the event. NewMexico telescopes ranging fromamateur backyard instruments to theNational Radio AstronomyObservatory’s Very Large Array will beaimed at Jupiter throughout mid-July.Around the world, scientists arepreparing to make the most of thisunique event.

(For more information, contact NationalRadio Astronomy Observatory, ArrayOperations Center, Socorro, NM 87801;(505) 835-7000--ed.)

Have you ever wondered...

...Why EarthquakesOccur?A.Very Brief History of Seismology

Richard AsterAssistant Professor of Geophysics,.New Mexico Tech

What is an earthquake? Thisquestion probably has been asked eversince human beings have been able towbnder about the natural world.However, comprehensive insight intothe causes of earthquakes has only beenachieved during the past century, andmostly during the past 50 years.

Predating the scientific era,earthquakes and othernaturalphenomena were widely ascribed todivine influences (often involvinggigantic manifestations of familiaranimals). In Japanese tradition, for.example, earthquakes were consideredto be caused by the stirrings of anenormous catfish, the namazu, which

lived in the mud beneath the Earth. InHindu mythology, earthquakes wereattributed to the shifting of one or moreof the eightgreat elephants thatsupported the Earth. In the OldTestament, earthquakes were /considered to be the instruments of avengeful God. More secular thinkers,such as Aristotle, speculated thatearthquakes were the result of windsaccumulating in the Earth’s interior.Like many of Aristotle’s hypotheses,this, combined with the concept ofearthly manifestations of God’sdispleasure with human beings,remained a widespread explanation forearthquakes in Europe throughout theMiddle Ages.

Despite subsequent early attemptsby natural philosophers during the Ageof Reason to associate earthquakeswith electrical,, atmospheric, or vaguesubterranean volcanic effects, progresson understanding earthquakesremained ponderously slow

Life Geology, Spring 1994

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throughout the 17’" and 18’h centuries. Arun of potable earthquakes nearpopulated areas, in Europe .and theNew World [London (1750); Boston’(1755); and especially the cataclysmicevent-near Lisbon (1755)] spurred newinterest and observations. Aparticularly important observationdocumented during this time was thatthe destructive force of earthquakeswas observed to propagate as a seismicwave. Analogous to ocean or soundwaves, but traveling through the solidEarth, seismic waves are sometimesvisible to the eye.during very .strongearthquakes.

Once it became clear to the scientificcommunity that earthquakes wereintimately related to the propagation ofseismic waves through the solid Earth,understanding progressed relativelyrapidly. The first seismometers,instruments for quantitativelymeasuring the motion of the Earth as afunction of time, were constructed bythe Englishman John Milne in.the1880’s. These instruments weresufficiently sensitive so that seismicsignals from large earthquakes couldbe recorded at quiet sites anywhere inthe world. Milne’s instruments wereeventually deployed throughout theBritish empire, and the first crudeworld maps of earthquake sourceregions, or epicenters, weresubsequently obtained.

What was happening at theepicenters that was generating seismicwaves? The answer became evidentfrom detailed studies of two notableearthquakes during this period thatshowed particular large and simplesurface ruptures. Investigations into thegreat 1891 Japan and the 1906 SanFrancisco earthquakes confirmed thatlarge earthquakes were caused by.sudden slippage on zones of lowfrictional strength (earthquake faults) the Earth. On such faults, strain energybuilds up gradually until some criticalstrength is overcome and slippagebegins. Slip then spreads unstably over

a large region and a vast amount ofstored energy can be released (the great1960 Chile earthquake, which was theresult of an average of 21 m of slip overa fault-plane area approximately thesize of New Mexico, released theenergy equivalent of about a 20,000megaton bomb!). Most of the energyreleased during fault slip goes intolocal heating and alteration of the faultzone, but a few percent goes intoseismic waves that radiate out from thesource region and can circle the earthmany times. This elastic reboundprocess, in which earthquake faults aregradually Loaded, slip suddenly, andthen are gradually loaded again, wasfirst formally proposed by theAmerican seismologist Harry Reidfollowing his study of the 1906 SanFrancisco earthquake. Elastic ’reboundis an accurate model for mostearthquakes and has Withstood the testof time.

However, the elastic rebound modelbegs the question of the ultimate causeof earthquakes. How do earthquakefaults form, and where does the energycome from to load these faults in thefirst place? A comprehensive answer tothis question would have to waitanother half century and wouldultimately involve the overturning ofmany dearly held global geologicconcepts. In 1912, Alfred Wegenerpostulated his theory of continentaldrift, in which the Earth was notstatically cooling, with the continentsand ocean basins remaining nearlyfixed, but where continents somehowmoved through the ocean basins,colliding and splitting, buildingmountain ranges, and generatingearthquakes. Wegener’s visionaryhypothesis, although supported byfossil and geological evidence,particularly in the southernhemisphere, was largely dismissed bythe scientific establishment for decadesbecause he was unable to convincinglydemonstrate how continents couldsomehow plow through the rocks of theocean floor.

When the first relatively highresolution maps of the globaldistribution of earthquakes becameavailable in the 1930% it becameabundantly clear that the Earth’sseismic activity was not uniformlydistributed, as might be predicted by astatically cooling Earth model, butmostly (approximately 90%) occurredin steeply dipping sheets plungingfrom near the continent/ocean marginsto deep beneath the continents,reaching depths of over 600 km near the

CONVERGENT PLATES

Astheno6phere Lithosphere

PLATES MOVING PAST EACH OTHER

Aithenosphere

DIVERGENT PLATES

Figure 1raThe three basic" types of platemargins.

Lite Geology, Spring 1994

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Pacific rim (about 10% of the way to thecenter of the planet!). These previouslyunimagined Benioff zones were soonrecognized as enormous faults.Furthermore, examination of seismic ’waves coming from Benioff-zoneearthquakes indicated that the oceanfloor was diving into the interior of theEarth in these regions. If ocean floorwas disappearing in these subductionzones (and the Earth wasn’t shrinking!),where was new ocean floor beinggenerated? The definitive answer tothis question had to’ wait until detailedmapping of the ocean floor could beperfo~mec]. Beginning in the mid-1950’s, oceanic geophysical surveysuncovered another previouslyunknown major Earth feature, theglobal mid-ocean ridge, a great world-encircling volcanic system that suppliesnew material to the oceans at about thesame rate that old oceanic crustdisappears in the subduction zones.Although almost entirely hiddenbeneath the oceans, the mid-oceanridge does see daylight in a few spots,such. as Iceland.

From these and other observations,the present model of plate tectonicswas assembled by the late 1950’s. In it,the Earth’s surface is visualized as acollection of a dozen or so thin rigidiithospheriz plates, each containingoceanic crust (approximately 5 to 10 kmthick), continental crust (approximately25 to 60 km thick), or both. These platesare carried along at typical speeds of afew centimeters per year by convectioncur.rents in the underlying mantle. Suchcurrents are possible because, althoughthe mantle is overwhelmingly solid, itis capable of slowly flowing like aliquid over geological time. Hot, risingmaterial from the Earth’s interiorreaches the surface at the mid-oceanicridge system, while cold material sinks

at the subduction zones. The relativelybrittle plates together constitute thelithosphere, which e)~tends to a depthof approximately 100 km and thusincludes the outer crust and part of theupper mantle. The especially ductilezone underlying the lithosphere andextending to a depth of approximately350 km is called the asthenosphere.

Earthquakes, then, are’predominantly found at plate margins(Figt/re I), where one plate is eitherplunging beneath another (as insubduction zones), where plates ar~

. rubbing side’-to-side (as along the SanAndreas fault in California), or whereplates are pulling apart (as at the mid-ocean ridges). Because the lithosphericplates act like a brittle skin beingcarried along by ductile mantle flow,difficulties associated with Wegener’soriginal continental drift hypothesis ofcontinents somehow barging through

the.ocean basins were overcome in theplate tectonic model, and it is nowuniversally accepted. Some of thematerial that goes down in thesubduction zones melts and returns tothe surface, spawning large arcs ofVolcanoes, such as the Aleutian Islands.

Finally, we must ask where all theenergy comes from to keep the platesmoving. The answer lies in the Earth’sgeothermal heat budget. The decay ofradioactive elements in. the mantle(primarily m, U~, The2, and K(°)

generates the bulk of this heat (lesseramounts arebelieved to come from theEarth’s primordial heat and from theaccumulation of the solid inner core).The amount of geothermal heat

’ escaping to the Earth’s surface is about1/6000th of the amount of solar energyreceived and reradiated by the Earth.Thus the ultimate answer as to whyearthquakes exist is that Earth hassufficient internal heat to sustain mantle

¯ convection and plate tectonics!

Life Geology, Spring 1994

what if...New Mexico had a largeearthquake?New Mexico Earthquake PreparednessProgram (NMEPP)Robert Redden,NMEPP Program Manager,New Mexico Department of Public Safety

What is the NMEPP?In October 1992, the Emergency

Management Bureau, Department ofPublic Safety, introduced a new programto enhance the State’s comprehensive systemfor emergency management andpreparedness. After almost two years ofdeveloping a program plan, NewMexico joined 31 other states as part ofthe National Earthquake HazardsReduction Program (NEHRP), program that was directed by theEarthquake Hazards Reduction Act of1977.

Why does New Mexico need anearthquake program?

Several agencies have beenconducting research and providinginformation on earthquakes in NewMexico for a number of years: NewMexico Bureau of Mines and MineralResources, New Mexico Institute ofMining and Technology, and the U.S.Geological Survey (USC~). Based their information, the USGS and theFederal Emergency ManagementAgency (FEMA) designated NewMexico as a moderate risk state forearthquakes.

How is the this risk designationassigned?

New Mexico’s seismic vulnerabilitywas determined from three criteriabased on the occurence of:

(1) historic large earthquakes(magnitude M7.0 or greater) thathave occurred near the state andformed fault scarps;

(2) moderate’earthquakes (M5 -M6)that have occurred in New Mexicobut are unrelated to surface faultmovement (i.e., randomearthquakes, such as those thatoccurred in 1906 [Socorro], 1935[Belen], 1965 [Dulce] and 1992[Rattlesnake Canyon nearCarlsbad]); and

(3) surface faults in New Mexicothat have been active in thegeologically recent past (within thelast 250,000 years) and that couldgenerate a large earthquake (M7.0 M7.5) in the fu’ture.

How does New Mexico’s moderaterisk designation compare to otherstates?

California is categorized as having avery high risk, whereas Arizona isconsidered a high risk state.

How does this moderate-riskdesignation affect New Mexico?

¯ The moderate-risk designationmade New Mexico eligible for FEMAfunding that will allow the state todevelop an effective earthquakepreparedness program. For the fiscalyear 1994, FEMA allocated more than$50,000 for the New MexicoEarthquake Preparedness Program.FEMA supervises the administrationof the funding for the program andprovides program guidance, whereasthe technical support at t~ie nationallevel is coordinated by the USGS,National Science Foundation, and theNational Institute of Standards andTechnology.

What will the New Mexico programaccomplish?

The goal of the New Mexico programis to establish the foundation for aneffective statewide earthquake hazardmitigation and preparedness program.These effqrts will focus on reducingthe state’s vulnerability to the effects ofdamaging earthquakes. Theprogram

initially concentrates on hazardidentification, vulnerability analysis,and public awareness and education.Mitigation, preparedness planning,and formation of a State Seismic SafetyCouncil are other key elements of theprogram.

Program objectives for Fiscal Year1993 supported the goals listed aboveand included the following: beginninginitial hazard analysis and

Ivulnerability studies, as well asconducting public awareness andeducation activities in cities andcounties along the Rio Grande valley.These communities were selectedbecause of their population densitiesand their proximity to the Rio Granderift, an area of known active faults andearthquake activity. The rift extendsfrom Colorado to the Mexican borderand roughly follows the Rio Grandevalley. Other area~; of the state will beexamined as the program evolves.

What is the future of the NMEPP inNew MexiCo?

The program is augmented by theactivities of many individuals fromeducational and scientific institutions,public agencies and the private sector.Experts from many fields, such as theEarth sciences, engineering, education,utilities management, government, andemergency management are applyingtheir considerable skills to helpdetermine the program’s direction,develop statewide seismic safety policy,and manage the volumes of data onseismic activity in New Mexico. Manystate agencies have already set a loftystandard for cooperation andcommunication on earthquake issues byproducing information, materials,advice, and technical expertise.

Additional information aboutearthquakes in New Mexico can beobtained by contacting Bob Redden,Earthquake Preparedness Office, at (.505)827-9254, or by contacting him at theDepartment of Public Safety, ATTN:EMPAC~ P.O. Box 1628, Santa Fe, NM .87504.

Lite Geology, Spring 1994

Glossary for Understanding EarthquakesAftershock~’An earthquake thatfollows a larger earthquake, or mainshock, and originates within a few faultlengths of the main shock.

Amplitude--Half the height of a wave’screst (high point) above the adjacenttroughs (low points).

Asthenosphere---The !ow-velocity,relatively ductile portion of the mantlethat underlies the Lithosphere. Extendsfrom approximately 100 km to 350 kmdepth.

Benioff zone--A plane of earthquakefoci dipping beneath the continents.Benioff-zone ’earthquakes primarilyindicate ~e top Of a subductinglithospheric plate.

Body waves---Waves that move throughthe body (rather than the surface) of theEarth. P-waves and S-waves are body

i ,waves.

¢

Compression--Squeezing, being madeto occupy less space. P-waves are calleflcompressional waves because theyconsist of alter.hating compressions anddilations.

Continental crustmThe silica andaluminum rich, relatively light rocksunderlying the continents. Thicknessranges from about 25 km to 60 kmunder mountain ranges.

Continental driftmThe original theoryof continental motion through geologictime. Superseded by plat~ tectonics.

p

Convection--A process of heat transferin a liquid by vertical motion, withwarm material rising and cold materialsinking. Convection in the Earth’smantle is the root driving mechanismfor plate tectonics.

Core The region~f the Earth from thebase of the mantle (about 2900 kmdepth) to the center of the Earth (about6370 km). Thought to consist of mostlyiron-nickel alloy, the outer core isliquid and the inner core (beginning atabout 5070 km) is solid. The mainsource of the Earth’s magnetic field.

Gordon was prepared for an earthquake.

FauitmA break or fracture of the Earth’scrust along which movement has takenplace. Faults are in some cases detectedby observing offset strata or streamvalleys.

Focus (pl. loci)raThe point within theEarth that is the center of anearthquake, where strain energy is firstreleased as wave energy (synonym:hypocenter).

Force-~-The cause or agent that puts anobject at rest into motion or affects themotion of a moving object. Gravity is avertical force; earthquake shakingincludes both horizontal and verticalforces.

Foreshock~An earthquake thatprecedes a larger earthquake, called themain shock, and originates along thesame fault as the main shock.

Frequency~The rate at which a motionrepeats, or oscillates. In this context,frequency is the number of oscillationsin an earthquake wave that occur eachsecond. A building’s frequency is therate at which it swings. /

Lite Geology, Spring 1994

Crust--The outermost layer of theEarth, the base of which Is globallyindicated by an abrupt increase inseismic velocity, two fundamental typesexist, continental and oceanic.

Dilation--Expansion, being made tooccupy more space. .,

Duration~The length of time thatground motion at a given site showscertain characteristics. Mostearthquakes have a duration of lessthan one minute, in terms of humanperceptions, but waves from a largeearthquake can travel around the worldfor hours.

Earthquake hazard~Any geological orstructural response that poses a threatto human beings and theirenvironments.

Elastic reboundDA process of elasticstrain buildup followed by suddenearthquake fault slip.

Epicenter---The point on Earth’ssurface directly above the focus of anearthquake.

Geothermal heatmHeat within theEarth, primarily thought to be due tothe decay of long-lived radioactiveelements. The ultimate cause ofearthquakes and volcanoes on Earth.

GravitymThe force that causes objectsto be attracted to each other. Gravity isespecially noticeable when an object ofgreat mass, such as the Earth, attractsobjects of lesser mass, pulling themtoward its own center.

Hanging wall--The overlying side of afault.

Hazard~A risk; an object or situationthat holds the possibility of risk ordamage. Some geologists reserve theterm "hazard" for natural processes,and "risk" for impacts on humans andstructures.

Intensity--A subjective measure of theamount of ground shaking anearthquake produce’s at a particular site,

~, based on human observations of theeffect on human structures and geologicfeatures. The Modified MercalliIntensity scale uses Roman numeralsfrom I to XII.

Isoseismal line--A line on a map thatencloses areas of equal earthquakeintensity. It is usually a closed curvecon!aining the epicenter. *

Joint~A break or fracture in brittlerocks along which differentialmovement has not taken place parallelto the break.

Landslide---An abrupt movement ofsoil and/or bedrock downhill inresponseto gravity. Landslides can betriggered by an earthquake or othernatural causes.

LiquefactionBDuring. earthquakes,fine-grained, water-saturatedsediments lose their former strengthand behave like a fluid.

Lithosphere---The outer, solid layer ofthe Earth that comprises the tectonicplates. The lithosphere extends toapproximately 100 km depth and thusincludes the crust and uppermostmantle.

Longitudinal waves--P-waves. Thisterm is used to emphasize thatP-waves move particles back and forthin the same line as the direction of thewave.

Love waves-~-Surface waves that °move in a back-and-forth horizontalmotion perpendicular to the line ofpropagation.

Mantle--The region of the Earthbeneaththe crust and above tl~e core.Comprises more than 80% of the Earthby volume.

Magnitude-r-A number that describesthe overall size of an earthquake,determined by measuring the motionsrecorded on a seismograph andcorrecting for the distance from theseismograph to the epicenter of theearthquake. Many different magnitudescales are in use, each based on adifferent attribute of the seismic signalsfrom earthquakes.

Modified 1Vlercalli Scale of 1931--aqualitative scale of earthquake effectsthat assigns an intensity’ to the groundshaking for any specific location on thebasis of observed effects. Mercalliintensity is expressed in Romannumerals.

Natural hazard~Any of the range ofnatural Earth processes that can causeinjury or loss of life to human beingsand damage or destroy human-madestructures.

Normal fault~A fault in which thehanging wall appears to have moveddownward relative to the footwall.

Oceanic crustmThe silica andmagnesium rich, relatively heavy rocksunderlying the continents. Thicknessranges from about 5 km to 10 km.

Oscillation, or vibration~Therepeating motion of a wave or amaterial. Earthquakes cause seismicwaves that produce oscillations, orvibrations, in materials with manydifferent frequencies. Every object hasa natural rate of vibration that scientists

call its natural frequency. The naturalfrequency of a building depends on itsphysical ch~aracteristics, including thedesign and the building materials.

P-waves--Primary waves, so calledbecause they travel faster than S-waves,or secondary waves. These waves carryenergy through the Earth aslongitudinal waves, moving particlesback and forth in the same line as thedirection of the wave.

Period--The time between two wavecrests.

Plate tectonics--A model of Earthevolution in which rigid lithosphericplates migrate in response to mantleconvection currents.

’PredictionBA statement thatsomething is likely to happen! Aprediction is usually only as reliable asits source.

Qualitative---Having to do withperceived qualities; Subjective.

Quantitative---Having to do withmeasurable quantities; objective.

Rayleigh waves--Surface waves thatcarry energy along the Earth’s surfaceby elliptical particle motion, whichappears on the surface as a rippleeffect.

Recurrence interval--The approximatelength of time between subsequentearthquakes in a specific area ofseismic activity.

Resonance---A buildup of amplitude (ameasurement of the wave crest) in physical system (such as a building)that occurs when the frequency of anapplied oscillatory force (such asearthquake shaking) is close to thenatural frequency of the system.

Retrofitting--Making changes to acompleted structure to meet needs thatwere not considc~red at the time it wasbuilt; in this case, to make it better ableto withstand an earthquake.

Richter magnitude---The number thatexpresses the amount of energy

Lite Geology, Spring 1994

released during an earthquake, asmeasured on a seismograph or anetwork of seismographs, using thescale developed by Charles Richter.

Richter ScaleDThe magnitude scaledeveloped by Charles Richter in 1935as a means of categorizing localearthquakes. The Richter scale uses alogarithmic decimal format; anearthquake measuring 7.0 moves therecording needle 10 times the distanceas an earthquake measuring 6.0.Risk--Probability of loss or injury asthe consequence of a hazard.S-Waves--Secondary waves; wavesthat carry energy through the earth invery comp!ex patterns of transverse(crosswise) waves. These waves movemore slowly than P-waves (in whichthe ground moves parallel to thedirection of the waves), but in anearthquake S-waves are commonly ofgreater intensity.

Seismicity--Earthquake activity.

Seismic--Of or having to do withearthquakes or earthquake-like waves.

Seismic zone---A region in whichearthquakes are known to occur.

Seismogram--The record ofearthquake ground motion recorded bya seismograph.

Seismograph-:--An instrument tha~ -detects, magnifies, and recordsvibrations of the Earth, especially .earthquakes.

Seismology--The scientific study ofearthquakes.

Stick-slip movement--A jerky, slidingmovement along a" surface. It occurswhen friction between the two sides ofa fault keeps them from slidingsmoothly, so that stress is built up overtime and then suddenly released.

Strike-slip faulting--Fault movementin which the fault is close to verticaland the movement of each side ishorizontal parallel to the fault plane.

Subduction--The process in whichone lithospheric plate is moves downunder another plate and drawn backinto the Earth’s mantle.

Subduction zone--The region whereone lithospheric plate descendsbeneath another, Subduction zone’earthquakes comprise a Benioff zone.

Surface wave~--Waves that move overthe surface of the Earth. Rayleigh andLove waves are surface waves.

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Thrust fault--A fault in which thehanging wall appears to have movedup relative to the footwall, and the dipis 45* or less over much of its extent.

Transverse waves--Waves that vibrateparticles in a direction perpendicular tothe wave’s direction of motion (S-waves).

Wave height--The vertical distancefrom a wave’s crest to its trough (thismeasurement will be twice theamplitude measured for the samewave).

Wavelength--The horizontal distancebetween two crests.

(~m~’es: Federal Emergency ManagementAgency; Richard Aster, New Mexico Tech; BillHaneberg, Dave Love, and other staff, NewMexico Bureau of Mines and MineralResources)

Life Geology, Spring 1994

Herbert was ~not prepared for an earthquake.

,Tasty Quake

Materials for the teacher*A fist-sized rock

.Silicone putty (widely available asSilly Puttym)

.One pan of prepared gelatin dessert(see recipe)

.Clear plastic wrap

.Sugar cubes or dominoes

.Spoon for serving dessert

.Paper cups and spoons for individualportions

Procedure1. Prepare gelatin desert in advance

and refrigerate. These ingredients willmake one pan, Prepare more if youwish to have several small groupsperforming the demonstrationsimultaneously.

2. Write the-definition of an earthquak~on the board.

3. Explain that under the soil, there are¯ rock layers. These layers are understress because of activity within theEarth.

4. Explain that when these rocks areunder extreme stress they react morelike a plastic material, such as siliconeputty, than like the hard rock we seeabove the ground. Show rock andputty.)

5. Demonstrate with Silly Putty~, ordistribute several lumps so that eachsmall group, can do the activity forthemselves. (The putty will be difficultto break if it has beqn warmed by toomuch handling, so work quickly.)

Teacher Take Note:This recipe has been-carefully tested. To transmitwaves that can be seen easily, the panmust be metal, and it must be full nearly tothe top with the gelatin mixture.

a. First, stretch the putty slowly to showhow rocks react to slow twisting andpulling.

b. Next, shape it back into a ball andgive it a sharp tug with both hands.The putty will snap into pieces.

c. Explain that this reaction is similar towhat happens during an earthquake.

6. Explain that when rocks break inthis sudden way energy is rel*ased

in the form of waves. We’ can simulatethis release of energy by watchingwhat happens to a pan of gelatin.

7. Gently tap the side of the pan ofgelatin, while holding the pan firmlywitlf the other hand. Students shouldbe able to see the waves travelingthrough the gelatin. Compare thegelatin to the ground, the tap.of yourhand to the rock breaking, and thewaves in the gelatin to earthquakewaves. .

8. Ask the students to predict what willhappen when you tap the pan withmore force. Tap the pan harder. Is theirprediction confirmed? Repeat thesetwo steps several times, and be surethat all the students have a chancetosee the waves.

9. Cover the top of the gelatin withplastic wrap so it will be cloan enoughto eat later. Be sure the wcap touchesthe gelatin. Ask the students what theythink, happens to buildings during anearthquake. Then let them distributesugar cube or domino "buildings" overthe plastic wrap.

10. Repeat steps 7 and 8 above.Replace any buildings that are knockedover during the first trial. Allowstudents to construct different kinds ofbuildings and predict their resistance tothe "earthquake," then test theirpredictions.

11. Remove the’plastic wrap and servethe gelatin to the students.

Teachers: the above exercise was extracted from: Earthquakes--a teacher’s guide for K---6 aorades by the National Science Teachers Associa-tion, 1988. Copies of the complete curriculum, which was supported by the Federal Emergency Management Agency (FEMA), are available forNew Mexico teachers for free through NMBM&MR. Please send your request for a copy (one per school) on school letterhead to: Susan Welch,New Mexico Bureau of Mines and Mineral Resources, Socorro, NM 87801. Teachers outside New Mexico can write to FEMA, EarthquakeProgram, 500 C Street, Washington, D:C., 20472; request information on curriculum price and availability, and teacher training in your state..

Late Geology, Spring 1994

h i g hT E S

EARTH SCIENCE UPDATE.

Sources for EarthScience. InformationTeachers can receive free materialsincluding curricula, student handouts,and reference materials for schoolresource media centers by contacting:

U.S. Bureau of MinesGuy Johnson, Staff EngineerBuilding 20Denver Federal CenterDenver. CO 80225-0086

A free teacher’s packet including aposter, lesson plans, activities, and alist of mineral resource information canbe obtained by call!ng or writing to:

Mineral Information InstituteJackie Evanger475 17th Street; Suite 510Denver, CO 80202(303) 297-3226

The Environmental Protection AgencyProvides a free information hotline forradon. Call:

1-(800) SOS-RADON

Information on Earth Scienceprograms, pl’ojects, reports, productsand their sources is available from:

US Geological SurveyEarth Science Information Center(USGS ESIC)Call 1-(800) USA-MAPS

or in New Mexico, contact:Amy BudgeEarth Science Information CenterEarth Data Analysis CenterUniversity of New MexicoAlbuquerque, NM 87131(505) 277-3622

whats on line?T~achers--Check out the US Geological Survey il~formation available tothe public through the Internet using Mosaic software program. Wedownloaded this pamphlet. The pathway we used is:

http: //info.er.usgs.gov / public/disaster-day / pamphlet.html

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(editor’s note: Watch for more ideas on computerized geologicinformation in future issues. We would love to hear from our readersabout what systems and programs they are using. We will soon have anemail address)

YOU CAN HELP, TOOl~> Learn more about natural hazards

Take first aid classes

<~>Make a disaster plan with your family

. ~ Make a Disaster Supply Kit for your home

Check Off Supplies

<~ water <~ clothing & bedding

food ~ apeokll Items euchme modlcationl

first aid kittOOll & lupplioOincluding:<> eating utensilsO radio (battery operatedO f11ulhllght¢ lpere I~berl~0 can opemer<̄> matches0 fire extinguisher

r

~; For more detailed information, contact yourlocal chapter of the American Red Cross oryour local emergency manager.

~ ’Oet Involved in your ¢ommunlly Make lure e~m/one is ~red ~ natural dlulterl.Include your echool, local buelrteuel im¢l government offi~l.

Lite Geology, Spring 1994

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publication Sources:Earth Science Resource CenterOffice of Special Programs and, .Continuing EducationColorado School of MinesGolden, CO 80401(303) 273-3038

JFAX: (303) 273-3314

What’s Under Your Feet? is an earthscience activity hook for grades 4-8. Itsprice is $3.00 (plus sales tax inColorado).

Sharing Science with Children: ASurvival Guide for Scientists andEngineers is a guide to help scientistsand engineers who will be visiting aclassroom. Its price is $1.50 (plus salestax in Colorado).~

Sharing Science: Linking Students withScientists and EngineersDA SurvivalGuide for Teachers is a guide to helpteachers prepare to host a visitingscientist in the classroom. Its price is$1.50 (plus sales tax in Colorado).

take a trip...The UNM Southwest Institute106 Bandelier WestUniversity of New MexicoAlbuquerque, NM 87131(505) 277-2828

"The Borderlands - Past and PresentA program of the Southwest Institute ofthe University of New MexicoDates: Lectures June 20-July 1, 1994;One-week field program in JulyLocation: Lectures at University ofNew Mexico; field program touring SWNew Mexico, SE Arizona, and thenorthern border of Mexico.

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summer courses...Denver Earth Science Project (DESP)Course Offerings - Summer 1994Location: Colorado School of Mines

Paleontology and Dinosaurs (grades7-10)2 semester hours of graduate-levelrecertificati0n creditDates: June 6-9, 1994

Ground Water Studies (grades 7-9)1 semester hour of graduate-levelrecertification creditDates; June 16-18, 1994

Oil and Gas Exploration (grades 7-12) 2 semester hours of graduate-levelrecertification creditsDates: June 20-24, 1994

contact:Colorado School of MinesGolden, CO 80401(303) 273-3494FAX: (303) 273-3314

also...National Energy Foundation$160 Wiley Post Way, Suite 200Salt Lake City, UT 84116(801) 539-1406

The Mining Industry and Minerals is apublication filled with educationalarticles and activities for students. Itcosts 75 cents per copy, plus shipping& handliqg of $3.00 (or 10% of order if40 or more copies are ordered).

From the Mine to My Home is a 23" x35" poster published by the NationalEnergy Foundation. It details the stepsin mining from exploration toproduction to consumption torecycling. The price of this poster is

, $3.00, plus shipping & handling.

Note: if your mailing label lists you as a teacher (in NewMexico), your subscription automatic, and you need not return this form. For other readers, when confirming yoursubscription, please send in ~he form only once, or we’ll get confused!

Lite GeologyPlease confirm my free subscription D (Send in your confirmation one time only)

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Life Geology, Spring 1994

a parting shot...The focus for this issue has been on earthquakes---why they occur, how they are

studied, and how they could affect New Mexico. Educators and the public canobtain more information by contacting Bob Redden, NMEPP Program Manager inSanta Fe at (505) 827-9254. The Bureau (NMBM&MR) can supply earthquakeand other natural hazards information in the form of maps, articles, publications,and videos. Please contact the Publications Office for a price list. We will con-

itinue to explore more earthquake topics in future issues, so save this copy forreference. See you next time.! (editor, Susan J. Welch)

..’. :.’.:....0 . ¯. ¯0¯ ̄ ¯ °~

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I. I T E

is published quarterly by New MexicoBureau of Mines and Mineral Resources(Dr. Charles E. Chapin, Director and State

¯ Geologist), a division of New Mexico Tech(Dr. Daniel H. Lopez, President).

Purpose: to help build earth scien/:eawareness by presenting educators andthe public with contemporary geologictopics, issues, and events. Use Lite Geologyas a source for ideas in the classroom orfor public education. Reproduction isencouraged with proper recognition of

4the source. All rights reserved oncopyrighted material reprinted withpermission within this issue.

Lite Geology Staff InformationEditor: Susan J. WelchGeological Coordinator: Dr. Dave LoveEducational Coordinator: Barbara PoppGraphic Designer: Jan ThomasCartoonist: Jan Thomaswith inspirationfrom Dr. Peter MozleyStudent Editorial Assistant: Toby ClickCreative and Technical Support:NMBM&MR Staff

Mailing AddressNew Mexico Bureau of Mines and MineralResources, Socorro, NM 87801. Phone(505) 835-5410. For a free subscription,please call or wrRe. LiteGeology is printed

. on recycled paper.

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New Mexico Bureau of Minesand Mineral Resources

Publications OfficeSocorro, NM 87801

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Life Geology, Spring 1994 ̄l