PowerPoint Presentation

Earthquakes

What is an Earthquake?

Meckering Earthquake

Types of faults

Thrust fault Meckering Fault1968 6.9 magnitude

Normal fault Darling Fault300 million years agoPerth basin formation

Transform fault Christchurch fault2010 boxing day 4.9 magnitude

The Himalayas

Convergent boundaryLittle to no subductionThrust fault folding occurs

SynclineAnticline

HorstGrabenHorst

Where do Earthquakes occur?FaultsConvergent boundariesDivergent boundariesTransform boundariesIntraplate faults Earthquakes begin below the surface at a focus (hypocentre)The surface directly above the focus is the epicentre

https://earthquakesandplates.files.wordpress.com/2008/05/eqfocus.gif

How are Earthquakes recorded?Seismometer Pen remains stationaryApparatus moves with the earthEarthquakes recorded as line graphs of wavesMagnitude and location are extrapolated from multiple recordings

Earthquake measurement scalesSeismographs are used to estimate the magnitude of an earthquakeCalculated from wave amplitude and distance from originMagnitudes scales are logarithmicEach magnitude increase10x amplitude increase32x energy increase

Earthquake magnitude scalesRichter ScaleDeveloped in 1934Best for small med magnitude earthquakesLess accurate for med large earthquakesMoment Magnitude ScaleCan accurately estimate magnitude for small large earthquakesAnalogous to the Richter scale

Seismic waves

Waves travelling through the Earths layersGenerated by low frequency soundVolcanoes, earthquakes, explosionsBody wavesTravel through the deep Earth layersP-wavesCompression wavesS-wavesTransverse (shear) wavesCannot travel through liquidsSurface wavesCan only travel on a surfaceMost destructive of the waves

Earthquake effectsTsunamisSudden deformation of ocean floorMassive displacement of waterGeneration of extremely fast wavesBarely detectable in deep ocean (long wavelength, low amplitude)Devastating along the shallow coast (short wavelength, high amplitude)LandslidesDestruction of infrastructureLoss of life

Resisting Earthquake damageSome densely populated areas are very close to faults

Christchurch (NZ)Tokyo (Japan)Los Angeles (USA)Perth

Resisting Earthquake damageDampers

Base isolation