Earthquakes

Question 1

What is a Focus?

Answer 1

A place within Earth song a fault at which the first motion of an earthquake occurs.

Question 2

What is a Epicenter?

Answer 2

The epicenter is directly above the focus on Earth’s surface.

Question 3

What is a Fault?

Answer 3

A break in Earth’s crust along which blocks of rocks move.

Question 4

Where do earthquakes occur?

Answer 4

Most earthquakes occur at or near tectonic plate boundaries.

Question 5

Divergent Boundaries do?

Answer 5

Pull out
Earthquakes here tend to be shallow
Common along normal faults

Question 6

Convergent boundaries

Answer 6

Plates collide
Squeezing shortens and compresses the rock
Super strong earthquake
Common along reverse faults

Question 7

Transform boundaries

Answer 7

Plates slide past each other horizontally
Shallow
Common along strike-slip faults

Question 8

Body waves

Answer 8

Waves travel through earth’s interior

Move faster

Question 9

Surface waves

Answer 9

Travel along the surface of the earth

Causes more damage

Question 10

P waves

Answer 10

Pressure waves
Are the fastest
Also called primary waves because they are detected first
Can travel through solids, liquids and gases
Causes rocks to move back and forth in the direction the wave is traveling

Question 11

S waves

Answer 11

Also called secondary waves
Slower than p waves
Move rock from side to side
Can’t travel through liquids part of earth

Question 12

What are seismometers used for?

Answer 12

Seismometers are used to record seismic waves

When waves reach the seismometer, it produce a seismograph

Question 13

What are seismographs used for?

Answer 13

They’re a tracing of earthquakes motion.

They are plotted on a graph and scientists use the graph to pinpoint the location of the earthquake epicenter.

Question 14

How is the earthquake magnitude measured?

Answer 14

By the Richter scale and the moment magnitude scale

Question 15

What is the Richter scale and the moment magnitude scale?

Answer 15

Richter- measures ground motion from an earthquake

MMS- measures earthquake strength based on the size of the area, average distance faults moves, rigidity rocks in fault

Question 16

What factors determine the effects on an earthquake?

Answer 16

Magnitude 
-Magnitude damage 
Local geology
-Material waves travel through 
Liquefaction can cause ground to settle. Structures tilt or collapse 
Distance from epicenter
Distance from epicenter wave intensity 
Building construction 
More flexible structures more likely to survive strong round shakes

Question 17

How is the earthquake epicenter located?

Answer 17

The lag time scientists how far waves have traveled from the epicenter

Question 18

What is triangulation?

Answer 18

A process where the epicenter can be found by drawing circles around the seismometer stations on a map and tracking where each of the 3 circles intersect.

Question 19

What is magnitude?

Answer 19

It is the amount of energy released by an earthquake.

Question 20

What is lag time used for?

Answer 20

It’s used to find the earthquake’s epicenter.