►
From YouTube: EOSC 350 Lecture 4: Magnetics 2. Doug Oldenburg
Description
Second lecture on the use of magnetics in geophysics.
Slides are available at:
https://github.com/ubcgif/eosc350website/raw/master/assets/2_Magnetics/3_Magnetics.pdf
The Jupyter Notebook demonstrated is available through binders: http://mybinder.org/repo/ubcgif/gpgLabs/notebooks/Mag/InducedMag2D.ipynb and on github: https://github.com/ubcgif/gpgLabs/blob/master/Mag/InducedMag2D.ipynb
A
A
Okay,
that's
probably
just
check
it.
Well,
I!
You
know
it's.
Actually
it's
really
interesting.
Is
it
I
think
it's
exactly
not
a
particular
trivial
operation
to
have
you
like
50
or
60
images
of
people
and
then
to
easily
kind
of
quickly
go
around
and
kind
of,
say,
poop
scoop,
so
it's
it's
sort
of
what
am
I
is
one
of
my
personal
goals.
Is
that
somehow,
by
the
end
of
this
course
I
might
actually
know
everybody
will
see.
A
The
first
is
that
we
do
not
have
people's
emails,
so
we'd
ask
people
to
sign
on
and
to
give
us
your
email
yeah
without
your
email
address.
If
we
have
something
to
share
with
you
or
something
to
tell
you
or
ask
you,
we
have
no
way
of
connecting
so
on
the
US
350
site,
which
has
been
newly
modified
by
by
Lindsay.
A
A
A
A
A
And
so
here's
your's
the
various
apps
that
we've
got
the
one
that
you're
going
to
be
interested
in
is
this
magnetic
zap
and
that
kind
of
takes
you
back
to
where
we
were
just
looking
at
okay.
So
this
is
the
one
that
you
will
I
mean
you
can
either
use
it
directly
on
web
or
you
can
actually
download
it
and
run
it
locally
on
your
machine.
Let's
see
here,
let
me
go
back.
A
Okay,
so
we're
back
here
at
the
350
website,
so
that's
the
apps,
so
you
can
go
there
download,
especially
the
magnetic
app
or
run
it,
and
then
there's
some
resources
here.
So
there's
information
give
at
the
gpg.
You
got
the
binder,
for
course,
apps
and
then
you've
got
how
to
download
the
notebooks
from
github
and
the
one
that
we're
actually
interested
in
today
is
the
a
magnetometer
app
so
I'm,
not
sure
how
many
people
were
able
or
have
tried
to
download
this
magnetometer
app.
A
A
One
two,
three:
four:
that's
not
bad,
so
we
got
four
and
then
we've
got
at
least
three
more,
so
we
got
seven
effectively,
seven
magnetometers
at
the
end
of
the
lecture
I'm
going
to
try
to
sort
about
15
minutes
before
maybe
20
minutes
before
it's
just
interesting
to
do
a
little
exercise.
Perhaps
some
of
you
have
already
done
it.
There's
been
some.
A
You
know
a
little
bit
of
you
know
hidden
magnetic
material,
various
parts
in
in
the
room,
and
you
can
go
around
and
try
to
use
your
magnetometers
in
your
iphone
and
just
see
if
you
can't
find
these
things,
it's
a
very,
very
good
representation
of
what
of
how
geophysics
works
and
also
gives
a
pretty
good
idea
about
the
relationship
between
geophysical
data
and
how
you
might
find
something
compared
to
just
your
arbitrary
grilling
on
on
a
pattern.
I
think
it
it's
simple
but
effective.
It
kind
of
drives
that
point
so
do
that
at
the
end.
A
So,
just
to
quickly
refresh
where
you,
where
we
were
last
time
so
we're
looking
at
magnetics
and
we've
got
our
general
magnetic
experiment,
we
recast
a
source
and
we've
got
magnetic
susceptibility,
remember
that
was
the
ease
with
which
something
could
become
magnetized,
and
then
we
have
a
response
and
the
source.
What
was
our
source
Zach.
A
Our
source
for
this
for
a
magnetic
experiment
yeah.
So
that's
just
yours,
magnetic
field
at
points
in
various
directions.
Here's
a
psycho
like
a
magnet
like
this
with
magnetic
field
lines,
come
out
and
deployed
different
directions
of
the
earth,
I'm
a
different
job
at
different
places.
So
we
described
the
this
is
a
vector.
A
Anybody
else
yeah,
so
we
need
actually,
if
it's
a
vector,
then
we
need
three
pieces
of
information
yeah.
So
it's
it's
like
it
either
an
XY
or
is
it
or
if
it's?
If
it's
a
length,
then
it's
two
to
two
angles
and
we'll
use
both
of
those
I'm
particularly
use
the
declination,
which
is
the
angle
from
two
more
the
information,
the
dip
or
sometimes
it's
called
the
dip
that
angle
between
the
horizontal
surface
and
we're
20
and
then
the
length
or
intensity.
A
This
was
the
inclination.
The
inclination
is
especially
easy
in
the
sense
that
it's
pretty
vertically
down
at
the
top
and
vertically
at
the
bottom,
and
then
this
was
the
strength
of
the
Earth's
field.
The
main
thing
here
was:
the
field
was
very
small
at
the
equator
and
its
large
at
the
pole,
so
typical
values
at
the
equator,
bland
20,000,
nano
teslas
and
poles
or
more
like
70,.
A
The
important
equation
that
relates
the
magnetic
field,
which
we
H
and
the
magnetization,
which
is
the
dipole
moment
per
unit
volume,
is
the
magnetic
susceptibility.
So
that's
it
essentially
tells
you
what
the
strength
of
the
magnetization
is,
for.
You
know
any
particular
little
segment
in
the
earth
and
then
the
idea
is
that
we
kind
of
do
the
following.
Let's
suppose
that
we've
got
a
body,
that's
very
here,
this
is
what
will
simulate
with
the
app
we've
got
a
bear,
a
body,
it's
very
here
and
here's
our
perhaps
observation,
point
and
deadly.
Just
look
at
this.
A
Now
we've
got
a
magnetic
field,
that's
coming
in
from
the
earth,
and
this
gives
this
magnetizes
the
body
in
here
now
that
body
actually
acts
like
a
little
magnet
itself
and
then
that's
got
its
own
magnetic
magnetic
fields.
So
that's
the
basic
principle:
we've
got
an
inducing
field
or
external
feel
magnetizes
this.
According
to
that
equation,
that
involves
susceptibility.
It
gives
rise
to
this
body
being
magnetized
and
that's
got
its
own
deal
and
Lofton.
We
refer
to
that
as
V
sub,
a
where
a
ease,
anomalous.
A
And
then
we're
going
to
plot
these
us
some
data
I
will
talk
a
lot
about
that
today,
because
this
anomalous
field
that
we've
got
is
a
vector
field.
So
it's
got
three
components
every
time
we
plot
something
we're
just
going
to
be
plotting
like
a
single
scalar
number,
and
so
we're
going
to
have
to
decide
what
it
is.
We're
going
to
plot
like
an
X
component
of
Y
components
that
component
and
then
we're
going
to
get
an
image
that
looks
like
that.
A
Any
other
thing
that
will
often
do
is
draw
what's
called
a
profile,
so
we'll
just
take
a
line
like
just
some
observation
lying
across
here.
So
just
when
you
go
to
be
the
same
as
when
you
go
down
to
the
beach
on
on
Monday,
oh
yeah
bring
your
rain
suits.
Unfortunately,
we
I
know
this.
Every
year
we've
done
this.
It's
been
really
sunny
on
the
Monday
that
we've
done
the
experiment,
but
it
doesn't
sound
like
next
money's.
Gonna
be
great,
so
might
bring
something
keep
it
up
anyway.
A
So
we're
walking
along
the
there's
going
to
be
a
very
well
a
buried,
pipe
or
actually
some
rebar.
That's
just
underneath
the
sit
underneath
sand
and
then
you're
actually
going
to
acquire
data
just
over
one
line,
so
that
would
be
called
a
profile
line,
and
so
sometimes,
on
our
day
map,
you
just
have
a
line
and
then
we'd
look
to
see
what
is
the
magnetic
field.
A
That's
that
you'd
observe
their
being
able
to
sketch
this
out
is
probably
well
that's
going
to
be
the
key
to
dip
today's
lecture
and
it's
one
of
the
things
that
really
does
help
and
solidify
your
knowledge
of
all.
All
the
magnetic
fields
are
working
on
what
your
measurements,
with,
what
your
measurements
are
and
characteristics
of
them.
A
A
Through
these
different
slider
bars,
the
app
has
got
three
different
kind
of
components
of
functionality.
The
first
is
to
design
what
it
is
you're
trying
to
you
know
what
the
structure
is
of
the
object
that
you're
looking
for
right
now,
what
I've
got
it
is.
It
is
a
cue,
that's
buried
a
little
bit
below
the
global
surface
and
we've
got
a
volume
here
that
we're
interested
in
and
that's
our
geometry.
A
The
next
part
is
going
to
be
basically
burying
this
at
different
points
in
the
earth,
but
we
can
decide
where
we're
going
to
vary
it
depending
upon
the
inflammation
and
declination
of
the
Earth's
field,
as
well
as
the
strength
so
by
these
working
with
these
slider
bars
is
equivalent
to
putting
it
different
points
on
your
and
then
we're
going
to
have
the
fields
that
we
that
we
measure
so
they
could
be
an
X,
Y
or
Z
component,
and
then
we're
just
going
to
look
at
the
induced
magnetization.
Today.
A
So
the
first
thing
is,
we
got
an
object
that
we're
going
to
try
to
find
so
many
I
know.
Maybe
it's
an
unexploded
ordnance
or
maybe
it's
a
you,
know,
a
mineral
deposit
or
whatever
so
there's
a
particular
stay
awake,
that's
associated
with
that,
maybe
its
leader
say
or
10
meters.
You
say
all
something
like
that,
so
let's
bring
it
all
through
all
the
surface
of
the
earth
and
then
let's
draw
this
object
in
here
which
at
this
point
might
just
be
cute,
and
we
can
do
that
here
with
these
components:
XY
and
Z.
A
So
X
is
the
length.
So
this
object
is
in
three
dimensions
and
there's
an
X
alignment
and
I
said
and
the
X
direction
or
the
X
length
is
given
by
the
top
bar
here.
If
you
click
on
it,
you
know
we
can
make
it
can
make
this
thing
progressively
bigger
so
now
now
this
is
one
and
a
half
for
1.8
meters
in
this
direction,
whereas
the
wine
is
that
are
both
of
a
half
all
right.
So
working
with
those
33
slider
bars,
we
can
get
the
XY
and
said
directions.
A
In
something
okay,
so
that's
that's
great,
so
we'll
we'll
stick
with
that.
We
can
later
rotate
this
guy
a
bit,
so
we
could
make
it
a
sheet
and
then
rotate.
It
do
all
kinds
of
things,
but
now
we're
just
going
to
reach
gonna
be
very
simple.
The
thing
that
I
would
like
to
do
is
just
do
a
little
cube,
small
cube,
we're
going
to
bury
it
and
then
that
cube
is
going
to
give
rise
to
a
magnetic
field.
A
Hey
so
here's
the
object.
It's
now
a
half
meet
meter
on
each
side
and
it's
got
to
get
the
burial
in
this
case
is
zero.
So
that
means
that
when
we're
talking
about
the
depth
of
air,
that's
the
depth
to
the
top
face.
So
this
thing
is
sitting
basically
right
at
the
surface
of
the
earth,
but
we
have
a
this
thing
here.
Our
X
H
is
the
height
of
the
of
the
receiver
plane,
so
we're
actually
going
to
be
measuring
stuff
at
a
height
of
1
meter
above
people
here,
so
we've
got
the
block.
A
A
A
No,
let's
say
you
know
four
meters
or
something
plus
your
mind,
so
we
go
from
like
if
we're
gonna
have
this
at
00
x.
Coordinate
is
zero
blackboard
zero
here,
but
maybe
we
go
from
minus
2
meters
to
to
be
richer
or
something
like
that
and
see
this
way,
then
that's
controlled
by
these
X
limb
by
limb
value.
So
right
now
the
X
limit
is.
A
A
Okay,
so
now
we've
got
a
square
area
on
top
that
we're
going
to
be
looking
at.
Actually
it's
going
to
go
from
minus
52,
55
meters,
and
so
here's
our
area
that
we're
looking
at
and
now
we're
going
to
bury
this
guy.
So
that's
our
system,
so
we've
gone
through
minus
5,
25
meters
and
we've
got
this
thing
Barry.
What
we
know
what
to
do
is
to
look
at.
A
A
A
Yeah,
so
it's
it's
kind
of
like
it's
almost
I'm,
just
fine
with
it,
so
you're
always
going
to
be
looking
exactly
we're.
Also
the
decoration
is
0
and
if
you
look
in
here
so
there's
an
Ian.
So
that's
the
inclination
of
that
extra
milk
and
there's
the
declination,
so
this
is
at
90
and
zero.
So
that
means
that
means
that
the
magnetic
field
is
coming
right
vertically
down.
A
Okay,
so
we're
sitting
up
here.
So
you
can.
We
got
an
object
there,
then,
let's
just
just
make
another
plane
here
for
observations.
So
let's
say
this
is
the
X
Direction
y
direction
here.
So
this
guy
is
sitting
here.
The
magnetic
field
is
coming
vertically
down.
I
just
wrote
this
guy
here.
Let
me
clarify
this:
forget
we're
going
to
as
I
say,
use
two
symbols.
A
A
A
Okay!
Is
that
yes
use
that
kind
of
vacation
lon
des
crus
dick
you
a
unit
vector
pointing
in
a
pic
of
direction
problem,
so
we've
got
the
Earth's
feel
coming
down
here.
What
funny
vertically
down
I
mean?
Whatever
we
got
here
is
going
to
get
magnetized
at
Kappa
times
the
magnetic
field
age,
but
remember
the
relationship
between
B
and
H.
Was
that
there's
just
a
scalar?
A
You
not
so
at
the
equally
well
have
written
this
as
Kappa
B
over
you
not
so
we're
going
to
use
be
Vinny's
age,
we're
going
to
be
very,
very
consistent
and
clear
of
what
exactly
we
mean
by
both
of
them
and
you'll
just
get
used
to
kind
of
going
back
and
forth.
When
we
talk
about
magnetization,
we
always
write
things
in
terms
of
H.
When
we
talk
about
magnetic
field.
Who
are
you
talking
about
them,
flux,
density
and
go?
So
now?
We've
got
something
buried
at
this
location.
A
A
A
Then
we
have
meet
three
kind
of
numbers
to
describe
it,
so
we
could
write
this
in
terms
of
the
X
component
or
the
Y
component
or
the
zip
component.
We
can
take
any
in
any
of
those
components,
and
if
we
do
that,
then
this
is
what
we're
going
to
get.
So
let
me
first
of
all
go
back
here.
So
here's
the
component
and
we're
going
to
take
BZ.
A
A
A
A
Those
are
some
pretty
big
numbers.
Iron
is
in
the
order
of
a
hundred
most
of
the
susceptibilities
we
saw
in
that
table.
The
other
day
were
for
Earth
rocks
or
more
like
10
to
the
minus
3,
or
something
like
this
so,
but
that
this
is
fine.
We
can
easily
kind
of
scale
things
back
okay,
so
we
get
this
particular
diagram.
A
A
Ok,
so
now
I
look
to
see
what
happens
here
and
now
we
think
about
the
the
magnetic
field
so
which
way
is
the
magnetic
field,
so
you're
you're
sitting
here
at
the
surface,
so
which
way
is
magnetic
field
pointing
ready
he's
pointing
down
right.
So
in
our
notation
here,
if
we
were
going
to
plot
this
value,
would
you
put
its
positive,
a
replot
as
negative
right,
and
so
that
is
exactly
what
we're
seeing
here.
Is
that
it's
just
sort
of
this
kind
of
big
negative
and
from
symmetry?
Of
course,
you
could
feel
like
it's.
A
A
Ok,
so
that's
the
ticket
think
about
a
magnet
into
the
ground,
think
about
the
fields
that
are
coming
out
and
now
you're
thinking.
Ok,
I'm
at
this
particular
location,
which
way
is
everything
pointing
if
it's
pointing
in
the
direction
of
mind,
coordinate
positive
axis,
I'm
going
to
false
positive,
and
if
it's
in
the
other
direction
it
could
be
negative
and
then
I'm
just
starting
to
kind
of
sketch
that
out
and
clearly
the
the
strongest
value
of
the
fields
are
going
to
be
right
here.
Right
and
the
weakest
ones
will
be
over
here.
A
A
Duration,
rewind
that
tape,
because
I
said
something
wrong.
Nobody
other
things:
not
human
I
was
one
step
ahead
of
myself.
Thinking
about
the
exit?
Okay.
So
if
we
get
the
magnetic
field,
here's
our
magnetization,
here's
our
magnetic
field,
and
now,
if
we
plot
the
X
component,
so
now
we
notice
that
here,
okay,
if
we're
sitting
here,
it's
pointing
back
this
way.
So
that
means
the
X
components
going
to
pause
a
ridiculous
so
up
here,
it's
going
to
be
negative
and
overhear
us,
and
so
right
here.
A
If
we
looked
at
these
values
here,
it's
going
to
be
very
negative
right,
so
we're
probably
didn't
even
go
down
like
this
and
then
at
this
particular
point
here
when
the
fields
are
coming
down,
it's
going
to
be
zero,
so
we've
got
to
have
a
zero
crossing
and
now
on
this
side,
we've
got
magnetic
fields
pointing
this
way.
It's
going
to
be
positive
up
here
soon,
I
guess
so
the
sketch
is
going
to
let
something
like
that,
so
the
profile
cross.
There
should
be
like
this
now
we
can
see
right.
A
So
if
you-
and
this
is
the
thing
that
makes
magnetics
a
little
challenging-
is
that
if
I
take
that
same
object
and
I
bury
it
at
the
equator,
I
got
a
whole
different
kettle
of
fish
going
right,
because
now
my
inducing
magnetic
field
is
this
way
right,
so
that
the
anomalous
so
now,
if
I
plot
it
on
a
plane
like
this,
if
this
was
north,
when
this
was
south
yo,
here's
my
object,
it's
magnetized
in
this
direction.
So
now
my
magnetic
fields
look
like
this.
A
So
now,
I'm
sitting
at
the
surface
of
the
earth,
and
now
my
magnetic
fields
are
looking
like
this.
If
I
look
at
the
x
component
of
the
magnetic
field
here,
I
find
that
whoa
wait
a
minute.
It's
got
to
be
a
great
big,
positive
value,
so,
whereas
here
the
x
component
was
zero,
if
I'm
at
the
equator,
the
X
component
is,
is
very
large
and
I'm
going
to
have
a
very
different
signature.
So
watch
what
happens
if
I
take
this
and
bury
it
at
the
equator,
how
do
I
do
that?
A
A
It
now
looks
something
like
that,
so
the
signatures
will
change
depending
upon
where
you
are
on
the
on
the
Earth's
surface,
and
that's
why
you
have
to
remember
you
let
this
magnetic
field
of
the
earth
is
constantly
changing,
because
each
time
you
bury
something
that
actually
it
gets
magnetized
in
you
know
different
directions,
and
that
means
that
the
character
of
the
field
is
going
to.
So,
unlike
some
other
things,
you
know
doesn't
matter
whether
you
bury
the
north
pole
or
softball
yeah,
you
get
saved
it's
also
in
magnetics.
It
does
so.
A
A
A
Just
trying
to
see
okay
can
I
find
regions
of
where
they
are,
and
the
interesting
point
is
that
we're
rocking
when
you
find
something
we
give
you
some
chalk
and
you
can
make
a
little
X
on
it
and
but
without
peeking
I'm
in
the
ground,
and
it
will
take
a
look
to
see
how
many
of
these
things
we
Wow
and
to
have
sometimes
there's.
What's
known
as
false
positives,
you
find
things
to
be
paper
there,
but
they're.
Not
so
we
had
14
for
iPhones.
Can
you
load
up?
Magnetometer
I've
got
a
magnetometer
apples.