Earthquakes

Question 1

What is an Earthquake

Answer 1

• Shaking or vibration of the ground. Release of built up stress.
• The deformed rock breaks along a fault.
• Snap back to original position after fault (elastic rebound)

Question 2

What are the 3 kinds of faults?

Answer 2

1. Normal Fault (tensile stress)
2. Reverse Fault (Thrust faults)
3. Shearing forces (Strike slip faults)

Question 3

What is the focus?

Answer 3

Spot on a fault that is the location of the first break.

Seismic waves travel outwards from this spot.

Question 4

What is directly above the focus?

Answer 4

The epicenter.

Question 5

Richter Scale

Answer 5

Way of measuring an earthquake in terms of the amount of ground displacement from the epicenter.

Question 6

What are the 3 types of seismic waves?

Answer 6

1. P waves
2. S waves
3. Surface waves

Question 7

What is a P wave?

Answer 7

Primary waves. Moves parallel to the direction of movement (Moves faster in solids than liquids)

Question 8

What is a S wave?

Answer 8

Secondary waves. Moves perpendicular to the direction of movement. (Only travel through solids.)

Question 9

What is a Surface wave?

Answer 9

Only on earths surface. (Slowest but most damaging)

Question 10

How does a Seismograph work?

Answer 10

Measures the magnitude and time between the P, S, and Surface waves. Also tries to pinpoint where an earthquake happened.

Question 11

What is the purpose of having multiple seismographs?

Answer 11

To measure the different times on the P, S, and surface waves in order to pinpoint where the earthquake happened. (Where they all intersect)

Question 12

How deep is the Earths crust?

Answer 12

0-40km

Question 13

What is Earths radius?

Answer 13

6370km

Question 14

Density of the Continental Crust?

Answer 14

2.8g/cm3

Question 15

Density of the Oceanic Crust?

Answer 15

3.0g/cm3

Question 16

Density of the Mantle?

Answer 16

3.4g/cm3

Question 17

What is a Shallow Earthquake?

Answer 17

Divergent boundaries/ transform faults/on continents due to the crust moving.

Question 18

What is a Deep Earthquake?

Answer 18

At subduction zones because the lithosphere is forced into the asthenosphere.

Question 19

What is isostatic rebound?

Answer 19

the rise of land masses that were depressed by the huge weight of ice sheets during the last ice age

Question 20

What is liquifaction?

Answer 20

It happens when soil with water in it is shaken. Reduces friction between soil particles that give it strength and causes it to become like quicksand.

Question 21

Most deadly affect of earthquakes.

Answer 21

Underwater earthquakes: Tsunami’s. Happens because of thrust faults. Tsunami’s travel at 1000km/h