Lecture Notes Chapter 8

Lecture Notes – Chapter 8 • What Are Earthquakes?

• When the ______, the ______along the edge experience immense ______

• Eventually the stress becomes too great and ______.

• Earthquakes are vibrations (in the ______) that result from the ______of

tectonic (______) plates.

• An “after shock” ______(that comes after a main event)

What appears to be the relationship between plate boundaries and Earthquake frequency?

______

Cause of Earthquakes - ______Hypothesis

when rocks are deformed – they ______, releasing stored energy.

Aftershocks and Foreshocks

An aftershock - earthquake that follows main earthquake (______).

A foreshock - earthquake that ______(sometimes).

Earthquake Storms – ______of ______earthquakes

8.2 Measuring Earthquakes - Earthquake Waves

Seismographs (Seismometers) ______earthquake waves.

Seismograms ______amplified, electronically ______

records ______/seismometers.

Types of Waves – Body waves

P-waves: ______waves PRESSURE WAVES

– LONGITUDINAL waves (______& stretch Earth’s crust)

– ______through rock than other seismic waves

– Travel through solids, ______

S-waves: ______waves SHEAR WAVES

– TRANSVERSE waves; ______through rock

– More ______(horizontal feel)

Travel ______

Surface waves

– only move across the Earth’s surface

– ______of Earth moving ______

– Cause the ______due to ______wavelengths Measuring Earthquakes to describe the ______

—intensity and ______.

– Richter Scale - Based on ______of the largest seismic wave

– Each unit = a ______energy increase (______size)

– Does ______estimate size of ______earthquakes well

– How many earthquakes each year are about the size of the Haiti Earthquake? _____

– Momentum Magnitude - amount of displacement along the fault zone

– ______- most widely used because it estimates

______released. Measures ______earthquakes

– List one of the large earthquakes, size and comments ______

– Mercalli Scale Based on an Earthquakes ______. ______scale

– ______Scale. What’s the strongest earthquake on Mercalli Scale? ______

Triangulation and Earthquakes

• Each station measures ______using the ______

• ______wave arrival times.

Triangulation Questions/Graph

1. What is on the y-axis? ______

2. What is the red squiggly line called? A s______

3. What is the difference in arrival times between the p and s waves? ______minutes.

4. How far away was the earthquake from the unknown seismograph station? ____ Estimate location.

Triangulation Earth Picture

1. How far away was the earthquake from Paris? ______km.

2. What ocean was the earthquake located in? ______. What kind of boundary is this? ______