1.1. Causes:Causes:A.A. plate tectonics (plate tectonics (elastic rebound elastic rebound

theorytheory)) faults “stick” faults “stick” buildup of energy buildup of energy

when they slip lots of energy is when they slip lots of energy is released = released = EARTHQUAKEEARTHQUAKE

B.B. glacial rebound theoryglacial rebound theory heavy glacier compresses ground heavy glacier compresses ground

ground springs back up = ground springs back up = EARTHQUAKEEARTHQUAKE

2.2. Earthquake terms:Earthquake terms:FocusFocus:: origin of energy release (deep underground)origin of energy release (deep underground)

EpicentreEpicentre:: point on surface above the focuspoint on surface above the focus

Liquifaction:Liquifaction: when land turns to mud when shakenwhen land turns to mud when shaken

Tsunami:Tsunami: giant wave resulting from earthquake in oceangiant wave resulting from earthquake in oceanlow in ocean, but fast movinglow in ocean, but fast movingfriction slows it down as it nears shore friction slows it down as it nears shore grows up to 80 m high!!grows up to 80 m high!!

Diagram of science!Diagram of science!

AftershocksAftershocks:: minor faults nearby breaking looseminor faults nearby breaking loosefollow major quakesfollow major quakes

Seismic wavesSeismic waves:: 3 types of waves emitted from 3 types of waves emitted from earthquakesearthquakes

1.1. P – waveP – wave (primary) (primary) push / pull push / pull

(compressional wave)(compressional wave) moves fastmoves fast

2.2. S – waveS – wave (secondary) (secondary) side-to-side motion side-to-side motion

(“shear” wave)(“shear” wave) moves more slowlymoves more slowly

3.3. L – waveL – wave (Love) (Love) rolling motionrolling motion last to arrivelast to arrive travels along surface travels along surface

of Earthof Earth most damagingmost damaging

3.3. Finding the Epicentre of an Finding the Epicentre of an Earthquake:Earthquake:

The distance between the The distance between the PP & & SS – waves – waves increases as waves travel outward from increases as waves travel outward from the epicentre.the epicentre.

How much time that passed between the How much time that passed between the detection of the detection of the PP & & SS – waves can be – waves can be used to determine how far away the used to determine how far away the epicentre was.epicentre was.

With 3 stations With 3 stations calculating calculating distances to distances to the epicentre the epicentre of the of the earthquake, earthquake, the epicentre the epicentre can be can be pinpointed.pinpointed.

Homework:Homework: Textbook Page 531, “Reading Check”, Textbook Page 531, “Reading Check”,

Questions 1-3Questions 1-3 Virtual Seismologist ActivityVirtual Seismologist Activity

2 Earthquake Certificates must be printed / 2 Earthquake Certificates must be printed / emailed with you name on thememailed with you name on them(can’t do San Francisco)(can’t do San Francisco)

http://nemo.sciencecourseware.org/VirtualEarthquake/VQuakeExecute.htmlhttp://nemo.sciencecourseware.org/VirtualEarthquake/VQuakeExecute.html