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Earth Sciences
ERTH 2415
Claire Samson

Natural DisastersFINAL EXAM MATERIAL LECTURE 1424LECTURE 14GEOMAGNETIC HAZARDSEARTHS MAGNETIC FIELD1Superposition of internal geomagnetic field Earth core and External geomagnetic field Ionosphere and Megetosphere1Internalresembles a magnet bar1Equator horizontal lines of force parallel to surface2Magnetic poles verticaldo not coincide exactly with N and S poles3Slow variations2Externaldisturbances affecting technological systems are caused by variations of the external geomagnetic field1Short durations and driven by solar activity2Geomagnetic Hazards1Extreme variation of geomagnetic field can have significant effect of technological systems2Effects observed for 150 years1Disturbances on the telegraph first stimulated investigations3Magnetic Stormtemporary few hoursfew days largescale perturbations of the external geomagnetic field due to high solar activity1Most frequent in peak of solar activity and declining phase of solar cycleSOLAR WIND1Solar Wind stream of charged particles flowing away from Suns corona in all directions takes 45 days to reach earth1Suns outermost atmosphere corona is hot and turbulant1Suns gravity cant hold it down2Upper fringes slow away in all directions ie solar wind2Strong gusts caused by 1Coronal Holes occur in small localized area of suns surface its violent explosions heat up material and shoot it into outer space2Coronal Mass Ejectionsstarscale events charged particles and radiation are released from the Suns corona in the vicinity of sunspots3Solar CycleApprox 11 years11610 Galileo made first sunspot observationand higher number of sunspots means more energetic sunEARTHS MAGNETOSPHERE2Region around Earth shielded from solar wind by the internal geomagnetic field1Extends several 100s kms above Earths surface beyong atmosphere2Solar wind compresses magnetosphere sunwardINTERACTION BETWEEN SOLAR WIND AND EARTHS MAGNETOSPHERE1Charged particles from solar wind create currents in the ionosphere 100km above the Earths surfaceIonospheric currents causes variations in the external geomagnetic field EM inductionEM inductionInduces telluric currents2Charged particles from the solar wind are guided by the magnetic field lines towards the polesExcites atoms in the upper atmosphereEmission of light aurora borealisSPACE WEATHER1Space Weather changing environmental conditions in space mostly related to solar activity2Can be predicted by1Satellite observations of the sun2Geomagnetic data from international3Knowledge of solar cyclesCONSEQUENCES ON TECHNOLOGICAL SYSTEMSProblems due to1Bombardment by charged particlesProblems affecting satellitesPressure from solar wind affect orbitCharged particles can interfere with circuitryCharge buildup can lead to violent discharge2Disturbances in the ionosphereProblems affecting the Global Positioning System GPSSignal delayed between ground and satelliteerror in distance determinationTemporary loss of signal3Electromagnetic induction effectsExtreme variation in external geomagnetic field induce telluric current along electrically conducting networksTelegraphFirst technological system involving long conductors on the Earths surfaceTelephonePower transmission linesAdditional telluric currents flowing along power transmission lines overheatingof transformers spurious signals in network control systemsPipelineslifetime 2040 yearsCathodic protection system against corrosion Pipeline maintained at a certain optimal electrical potentialDuring magnetic storms telluric currents cause the potential to go out of range leaving the pipeline unprotectedLECTURE 15PLATE TECTONICS AND VOLCANOESROCK CYCLE1Mineral naturally occurring inorganic solid with orderly internal structure and individual characteristics2Rock solid aggregate of one or more minerals3Rock Cycle processes by which older rocks are made into new rocks concept predates tectonic plate theory
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