3.a. earthquakes

Question 1

shallow focus depth

Answer 1

down to 70km

Question 2

shallow focus charecterisitcs

Answer 2

fracturing is a common occurrence due to the stress and pressure
normally low energy (some are high)
more damage (less energy is dissipated)
limited warning (P waves arrive with other waves)

Question 3

intermediate focus depth

Answer 3

70-300km

Question 4

deep focus depth

Answer 4

300-700km

Question 5

shallow focus plate boundary

Answer 5

transform/conservative

Question 6

deep focus plate boundary

Answer 6

destructive boundary
oceanic is subducted

Question 7

deep focus characteristics

Answer 7

less frequent
very powerful
depth and high pressure causes high temperatures
occur often in the Benioff zone

Question 8

Benioff zone

Answer 8

an inclined zone in which many deep focus earthquakes occur
situated beneath a destructive plate boundary where oceanic crust is subducted

Question 9

seismic primary (P) waves

Answer 9

body wave
longitudinal
fastest
least destructive

Question 10

seismic secondary (S) waves

Answer 10

body wave
(squiggle/worm shape)
second fastest
slightly more destructive than P waves

Question 11

seismic Rayleigh (R) waves

Answer 11

surface wave
cycling motion
slow
destructive

Question 12

seismic love (L) waves

Answer 12

transverse
slow
very destructive

Question 13

Richter scale

Answer 13

uses amplitude of seismic wave to determine magnitude (release of energy)
logarithmic
ground shaking is detected by seismometer/seismograph which produces a seismogram
no upper limit

Question 14

moment magnitude scale

Answer 14

measures energy released more accurately than Richter scale
energy released is related to geological properties (e.g. rock rigidity, area of fault surface and amount of movement along the fault)
most accurate for large earthquakes- relies on physical movement caused by an earthquake which is a result of energy
not used on microearthquakes (2.0 or bellow) these are recorded locally and not felt by people

Question 15

modified Mercalli intensity scale

Answer 15

measures earthquake intensity by its impacts and effects
qualitative and subjective assessment based on observations and descriptions
more meaningful to non scientists because refers to the effects on a place
scale of 1-12

Question 16

tectonic faults

Answer 16

a fault is a break in the crust where slabs of crust slip past each other
caused by stress building on rocks causing rocks to shatter.
faults usually occur on plate boundaries where the forces of plate motion compress, pull or shear the crust too much so the crust ruptures
large geological time scale

Question 17

Strike slip faults characteristics

Answer 17

Sheering creates this fault
Rocks on both sides of the fault slide past each other with little up and down motion
When a strike slip faults forms the boundary between two plates it becomes a transform boundary
Visible scar on landscape may appear

Question 18

Strike slip faults tectonic activity

Answer 18

Earthquakes occur along faults as blocks of continental crust rotate or move sideways out of the principle collision zone
Remain tectonically active

Question 19

Strike slip faults example

Answer 19

San Andreas fault: continental fault that extends 1200 km
Kunlun fault: formed on Tibetan plateau, successive earthquakes have caused visible scarring on the landscape

Question 20

Normal fault

Answer 20

Caused by tensional forces on the crust
Formed on angle so one section of rock is raised
Movement along the normal fault chases the hanging wall to slip downwards

Question 21

Normal fault example

Answer 21

Rio Grande Rift Valley in New Mexico
Two pieces of divergent crust

Question 22

How rift valleys are impacted by earthquakes

Answer 22

Evidence of the impact of earthquakes in the morphology of the Earth’s surface
Fault scarps/escarpments are created when extensional forces put the lithospheric plate under tension and vertical faults form
Earthquakes occur as graben sinks
Scarps are eroded over time and blend until landscape

Question 23

Reverse or overthrust faults

Answer 23

Compressional forces produce this fault
The fault has the same set up as a normal fault, but reversed
Just like a normal fault, one side of the reverse fault is at an angle of the other
This fault produced part of the Appalachian mountains in Eastern United States

Question 24

Fold belts

Answer 24

Compression from tectonic activity produces folds in Rick strata. This creates mountain ranges such as the Himalayas
This may influence costal landforms

Question 25

Anticline

Answer 25

Upbend

Question 26

Syncline

Answer 26

Troughs