Name_______________________________________________

Lecture I: EarthquakesTypes of Stress

Stress: a force that acts on a rock to change its shape or volume _____________:Squeezes rock together until it folds or break _____________:Pulls and stretches rock _____________:Pushes rock in 2 opposite directions

Faults Most faults occur long ____________________________ The force of plate motion pushes or pulls the crust until it __________ 3 types of faults

What is an Earthquake?

Earthquake: the shaking and trembling that results form the movement of rock beneath Earth’s surface. The force __________________________ causes earthquakes.

1. Plate movement creates __________ adding energy to the rocks.

2. Stress increases along a _____________ until the rock breaks. 3. Once it breaks the earthquakes releases LOTS of energy!

Focus and Epicenter

Earthquake begins in the___________________ (100km below Earth’s surface)

_________ : area beneath the surface where rock is under stress/breaks Epicenter: Point on the surface directly above focus

Earthquake Waves

Like ripples in a pond, __________________________ carry the energy released from an earthquake away from the focus, through the Earth’s interior, and across the surface.

Waves are like dominos – they transfer ________________!

STRIKE-SLIP: Rocks on either side of the fault slip past each other: Happens when there is _________________________

NORMAL: One part of rock is above fault, and the other is below: Happen when plates ____________ (pull apart)

REVERSE: One part of rock is above fault,

and the other is below: Happen when plates ___________________ (pushed together)

Types of Seismic Waves

_______________ Waves

The 1st to arrive They compress and expand the ground like an

accordion. Move through solids and liquids

_______________Waves

Arrive after P waves They vibrate up and down as well as side to side Only move through ___________

Surface waves

The ground surface rolls with a wavelike motion

Measuring Earthquakes

Mercalli Scale: Rate based on level of _________________ Richter Scale: Gives a magnitude based on the size of the seismic

waves (as measured by a _______________________) Moment Magnitude Scale: estimates the total

_________released by earthquake.

Where do Earthquakes Occur?

AT PLATE BOUNDARIES!

Locating the Epicenter of an Earthquake

Geologists use seismic waves to locate the epicenter Seismic waves travel at different _____________ P wave arrives first, S waves arrive second Scientists measure the _______________ between the arrival of S and P waves on a seismograph The ____________ away the earthquake is, the __________ the time difference between the arrival of S and P

waves

Earthquakes and Convection Currents?