Lectures 10-20

Question 1

what is Telluric?

Answer 1

electrical currents induced by variations in earths magnetic field

Question 2

what can Telluric’s affect?

Answer 2

telegraph and telephone lines

pipelines

power transmission

Question 3

what are magnetometers and electrodes used for ?

Answer 3

magnetometers = measure internal/external (geomagnetic field)

electrodes = measure Telluric currents

Question 4

what is magnetotelluric sounding

Answer 4

estimate electrical conductivity in subsurface

Question 5

electromagnetic surveying is?

Answer 5

creating an artificial magnetic field, induces currents in ore bodies

these currents generate a magnetic field at surface or air

Question 6

are metallic ore bodies more or less conductive than surrounding rocks

Answer 6

more conductive

Question 7

what stimulated investigations of extreme variations ?

Answer 7

telegraph disturbances

Question 8

internal geomagnetic field is due to?

Answer 8

movement of liquid iron caused by heat transfer and earths rotation

Question 9

how many NT is ottawas magnetic field?

Answer 9

56000 nt

Question 10

every few years what happens? every hundred thousand?

Answer 10

few years: magnetic poles wander around geographic

hundred thousand: north and south magnetic poles flip

Question 11

what causes disturbances in technological systems? and whats it driven by?

Answer 11

external geomagnetic fields, driven by solar activity

Question 12

define solar wind

Answer 12

stream of charged particles flowing away from suns corona (typically takes 4-5 days to reach earth)

Question 13

what are solar winds caused by?

Answer 13

coronal hole explosions in small localized areas of suns surface

Question 14

star-scale events are called

Answer 14

coronal mass ejections,

Question 15

what is the approximate solar activity cycle?

Answer 15

11 years

Question 16

what is a magnetic storm?

Answer 16

large scale disturbance in the external geomagnetic field

Question 17

when are magnetic storms most frequent?

Answer 17

peak of solar cycle

declining phase of solar cycle

Question 18

what is the magnetosphere

Answer 18

region around earth shielded from solar wind (internal geomagnetic field)

Question 19

charged particles in ionosphere cause what

Answer 19

ionospheric currents -> variations in the external geomagnetic field -> induce telluric currents

Question 20

true or false: we can predict space weather

Answer 20

TRUE

Question 21

list the 3 ways we use to predict space weather

Answer 21

satellite observations

geomagnetic data from observatories

knowledge of solar cycles

Question 22

what are the problems of magnetic storms?

Answer 22

bombardment of charged particles

ionospheric disturbances

electromagnetic induction effects

Question 23

what are the problems from particle bombardment

Answer 23

pressure affects satellite orbit

interfere with circuitry

lead to violent discharge

Question 24

what are the problems with ionospheric disturbances?

Answer 24

problems affecting GPS (signals are delayed)

loss of signal

Question 25

what are the problems with electromagnetic induction?

Answer 25

external geomagnetic field variations induces telluric currents, affects Telegraph, telephone, power lines(over heating), pipelines

Question 26

whats our mitigation technique

Answer 26

sensitive equipment be taken offline during magnetic storms.

space weather forecasters

Question 27

1989 magnetic storm Quebec what happend?

Answer 27

telluric currents made transmission lines unstable and quebec power grid collapsed

Question 28

how do magnetic storms destroy pipe lines?

Answer 28

cathodic systems that protect against corrosion go offline.