earthquakes (LEC 8)

Question 1

earthquakes occur when rocks return to their original, stress-free shape after overcoming the frictional forces exhibiting _________ _________

Answer 1

elastic rebound

Question 2

the _____________ is the point of where rock slippage occurs. also called the focus.

Answer 2

hypocenter

Question 3

the _________ is the location on the EARTH’S SURFACE, directly above the hypocenter

Answer 3

epicenter

Question 4

_______ are small earthquakes that often occur before major earthquakes by days or even by as much as several years

Answer 4

foreshocks

Question 5

__________ are earthquakes of lesser magnitude that occur after a strong earthquake

Answer 5

aftershocks

Question 6

what is a seismograph and how does it work

Answer 6

an instrument used to detect and record earthquakes, the main idea is that the base moves and the mass does not

Question 7

what are body waves

Answer 7

body waves are the waves that travel through the earth’s interior

Question 8

what are the two types of BODY WAVES

Answer 8

primary waves and secondary waves

Question 9

there are two types of body waves: P-waves and S-waves

what are the differences between them

Answer 9

primary waves are a push-pull waves: compressing and expanding the rocks in the direction of waves travel

secondary waves are when the rocks shake perpendicular to the direction of wave travel

Question 10

what are surface waves

Answer 10

surface waves are the waves that travel in the rock layers just below the earth’s surface i.e. travelling only through the crust

Question 11

surface waves cause the earth to move ______________ or _______________

Answer 11

up and down
side to side

Question 12

___________ have even greater amplitudes than S waves and retain their maximum amplitude for much longer

Answer 12

surface waves

Question 13

what is is the intensity of an earthquake vs the magnitude

Answer 13

intensity is a measure of the degree of ground shaking at a given location
based on the amount of property damage

magnitude is the amount of energy released at the source of the earthquake based on the data provided by seismographs

Question 14

what is the Modified Mercalli Intensity Scale

Answer 14

a scale to estimate
the intensity of an earthquake

Question 15

what are the drawbacks of the Modified Mercalli Intensity Scale

Answer 15

destruction may not be a true measure of the earthquakes’ actual severity because it depends only on the ground shaking and the building destruction. it does not take into consideration the population intensity, building design, and the nature of surface materials

Question 16

what is the Richter Scale

Answer 16

it is based on the amplitude of the largest seismic wave recorded on a seismogram and the distance to the epicenter

Question 17

what are some factors affecting earthquake destruction

Answer 17

*magnitude
*duration of shaking
*local geology
*population density where the earthquake occur
*distance from epicenter
*construction practices
*disaster response planning
*time: earthquakes during working hours in populated urban areas are
most destructive and cause most injuries.

Question 18

what are some major destructive forces that earthquake vibrations can trigger

Answer 18

*seismic vibrations
*liquefaction
*tsunami
*fire
*landslides and subsidence

Question 19

(true or false)

the effects of vibrations cause more injuries than any other earthquake
effect

Answer 19

TRUE

Question 20

what is liquefaction

Answer 20

a process in which unconsolidated materials that are saturated with water act like a liquid due to earthquakes

Question 21

(true or false)

a tsunami has more effect on a steep shore compared to a flat one

Answer 21

FALSE

a tsunami has more effect on a flat shore

Question 22

95% of the energy released by earthquakes originates in a few, narrow locations. where are these places

Answer 22

Circum-Pacific belt
Alpine-Himalayan belt
Transform faults
Intraplate earthquakes