Chapter 12 Study Notes Earthquakes

How and Where Earthquakes Happen Chapter 12 Section 1 How and Where Earthquakes Happen

1 _______ ________is the sudden return of deformed rock to its undeformed shape. Elastic rebound

2 The ______ ______ of an earthquake occurs at the focus. first motion

3 The _________ of an earthquake is the point on Earth’s _______ directly above the earthquake’s focus. epicenter surface

4 A ______ wave is a seismic wave that travels through the _______ of the earth. body interior

5 A ________ wave is a seismic wave that travels along the _______ of the earth. surface surface

6 P _______ are the ______ body waves. waves fastest

7 P waves can travel through ______, ______, and _______. solids liquids gases

8 P waves travel _______ through very _____ and not easily ____________ materials. fastest rigid compressed

9 S waves can only travel through ______. solids

10 Earth’s interior affects the _______ and _______ of seismic waves. speed direction

11 A _______ _____ is an area where no direct ______ _____ from a particular earthquake can be detected. shadow zone seismic waves

12 Earthquakes generally occur at _____ __________ where stress on rocks is the ________. plate boundaries greatest

Chapter 12 Section 2 Studying Earthquakes

13 A ___________ is an instrument that records the ground _________. seismograph vibrations

14 A modern ____________ consists of _____ sensing devices. seismograph three

15 A ___________ displays earthquake motion ________ by a seismograph. seismogram recorded

16 Scientists find the _________ of an earthquake by comparing the ______ times of P waves and S waves at _____ or more seismograph stations. epicenter arrival three

17 When seismologists record ______ times of P waves and S waves at three or more seismograph stations, they are looking for the earthquake’s ________. arrival epicenter

18 ___________ is a measure of the _________ of an earthquake. Magnitude strength

19 The Richter scale is based on ________. magnitude

20 The Richter scale measures the __________ of an earthquake using _______ ______. magnitude ground motion

21 The moment magnitude scale measures the _________ of an earthquake by the _____ size and the _________ that the fault blocks move. magnitude fault distance

22 The _______ _________ scale measures the _________ of large earthquakes the most ________. moment magnitude magnitude accurately

23 _______ is the amount of _______ caused by an earthquake. intensity damage

24 The ________ _______ scale measures the _________ of an earthquake. modified Mercalli intensity

25 Intensity ____ _(___)_on the modified Mercalli scale is described as causing _____ __________. XII 12 total destruction

Earthquakes and Society Chapter 12 Section 3 Earthquakes and Society

26 A _______ is a large ocean _____ that forms after a volcanic eruption, underwater earthquake, or landslide. tsunami wave

27 As tsunamis move toward shore the waves _______ in _____. increase height

28 ________ _________, __________, and undersea __________ may all cause a tsunami. Volcanic eruptions earthquakes landslides

29 During a ______ earthquake, buildings may _____ or _______. major sway collapse

30 You can prepare for an earthquake by gathering ______, ______, _________, and a portable _____. food water flashlights radio

31 If you are ________ during an earthquake, you should crouch under _______. indoors desk

32 During and after an earthquake you should stay _______ and follow __________. cautious instructions

33 A ________ ______ is an area in which strong earthquakes have occurred in the ______. seismic gap past

34 A _________ is a small earthquake that may precede a ______ earthquake. foreshock larger

35 Scientists study _______ ____, _____ _______, and __________ in order to predict earthquakes. seismic gaps rock changes foreshocks

36 Earthquake ________ is _________. prediction unreliable

The End