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Flashcards in Seismology and Faults Deck (55)
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1

what are seismographs?

instruments used to detect and record earthquake vibrations

2

seismographs are instruments used to ____ and _____ earthquake vibrations

detect, record

3

what do seismographs detect and record?

earthquake vibrations

4

The reports you get from a seismograph is called...

a seismogram

5

Modern seismographs use sensitive _____ and _____

optics, electronics

6

a seismograph measures...

the earth's vibrations in two different directions

7

How many directions does a seismograph measure the earth's vibrations?

two

8

what are the two directions measured by a seismograph?

- the horizontal movement of the Earth - Vertical Earth movement

9

Energy in earthquakes travels outward as _____

waves

10

What is the name of the originating point where a tectonic slip occurs?

the focus

11

Earthquake ______ emit outwards from the focus

waves

12

What are the two broad categories of earthquake waves?

1. Surface waves 2. Body waves

13

Where do surface waves travel?

along the earth's surface

14

What are the three characteristics of surface waves?

- travel along earth's surface - very destructive - are the last to reach the seismograph (slowest)

15

Where do body waves travel?

Through the Earth's interior

16

What are the two types of body waves?

- P waves - S waves

17

P waves are _______ waves

compressional

18

P waves can travel through....

solids, liquids, and gases

19

When P waves are emitted they travel in ______ directions including deep into the Earth

all

20

S waves can travel through...

any solid 

21

the wave motion of S-waves is...

perpendicular to travel direction 

22

What are s-waves called? 

shear waves 

23

are s-waves faster or slower then p-waves? 

slower 

24

How is the distance to the epicenter figured out? 

- from the seismogram

- by using the arrival times of seismic waves 

 

25

Which release more energy, earthquakes or volcanoes? 

earthquakes 

26

In order for a rock to break it has to have ______ and ______ on it. 

stress and strain 

27

What is stress? 

the force acting on a surface, per unit area 

28

Stress can be a force that is squezzing, which is called ________ or it can be a force that is pulling a rock apart, which is called _______, or it can be a force that is sliding past a a rock, which is called ______

compression, tension, shear 

29

Compression is a force that is...

squezzing the rock 

30

Tensional force is a force that is...

pulling a rock apart