Earthquakes

Primary vs Secondary Effects

Primary → occur as the ground is shaking, building collapse, surface faulting, liquefaction, landslides

Secondary → as a result after the ground stops shaking, fires, tsunamis, quake lakes

Deggs Model

Disaster lies at the overlap between a hazard event and a vulnerable population

Measurement

• Richter scale not used since 1979

• Moment Magnitude Scale → Mw, x32 each time

• Modified Mercallo → subjective

Prediction

• cannot predict earthquakes

• can forecast where earthquakes will take place

• 4235 seismometres installed in Japan

• Seismic Gap Theory and Unzipping Theory

Magnitude and Impact

somewhat correlated, higher potential for destruction at higher magnitudes

depends on location, time, development, depth of focus geology, time of year

Preparation/Mitigation Techniques

• drop cover hold

• fire and first aid kit

• emergency plan

• foundation bolts

• insurance

• gas meter shutoff

• cross beams

• bolted boiler and furniture

• shock absorbers

• fire breaks

• September 1st = Earthquake prep day in Japan

Focus/Hypocentre vs Epicentre

Focus/Hypocentre → point within Earth where faulting begins

Epicentre → point directly above focus

P and S Time Gap and Triangulation

P-S time gap indicates distance from epicentre, possible to triangulate exact epicentre

Earthquake Waves

Body Waves → move through the Earth

• Pressure → helicoidal

• Sheer → sinusoidal

Surface Waves → move along surface

• Rayleigh → move land up and down

• Love → move land side to side

Park’s Model

Shows how a hazard event can provide opportunity for improvement with adequate resources, pre-disaster → relief → rehab → reconstruction