►
From YouTube: EOSC 350 Lecture 8: Magnetics 6. Doug Oldenburg
Description
Final Lecture on magnetics in geophysics. Applications to unexploded ordnance.
Slides are available at:
https://github.com/ubcgif/eosc350website/raw/master/assets/2_Magnetics/3_Magnetics.pdf
A
Yeah
I
guess
so
I'd
like
you
to
says
not
duty.
If
people
have
questions
or
discussions,
we
can
do
that.
I
would
also
just
like
to
kind
of
go
through
a
little
bit
more
slowly.
A
few
of
the
things
that
have
to
do
with
application
of
the
applications
well
basically
fall
into
three
main
areas.
For
you
and
just
to
kind
of
be
aware
of.
What's
going
on,
is
we
had
kind
of
gone
over
a
little
bit
this
last
lecture?
I
was
thinking.
A
I
would
be
able
to
get
through
everything,
but
there
wasn't
enough
time
so
I'm
going
to
repeat
just
a
couple
of
slides,
but
here
is
basically
the
idea:
we've
got
magnetic
data,
it's
got
some
information
in
it
and,
depending
upon
what
scale
you're
looking
at
what
kind
of
problems
you're
interested
in
you
might
work
with
these
data
in
different
ways.
The
most
simple
is
just
to
look
at
the
date
of
themselves
as
they
okay.
A
Basically,
trying
to
understand
the
magnetic
signature
within
the
context
of
very
simple
bodies:
that's
where
our
dipole
comes
in
for
the
monopole
comes
in.
It's
where,
like
sheet
of
multiples,
could
come
in
that's
sort
of
in
that
domain
here
and
the
third
gets
down
to
greater
complexity.
We're
actually
saying
all
the
earth
is
really
complicated.
We've
got
a
3d
volume
up
there,
we're
going
to
try
to
see
if
we
can
interpret
what's
there.
A
So
a
couple
of
these
slides
that
we
talked
about
previously,
so
here's
just
looking
at
the
geologic
math
and
the
Magnetic
map
and
we've
shown
this,
and
you
can
see
that
just
by
looking
at
the
image
I,
you
can
make
the
correspondence,
especially
if
you
know
something
about
what's
happening
here.
Then.
Okay,
that
tells
you
that
that
makes
that
correspondence.
And
now
you
can
see
that
the
same
magnetism
kind
of
coming
up
here,
maybe
that's
delineating
this
whole
region.
A
So,
as
perhaps
as
I
said,
one
of
the
biggest
uses
of
magnetics
is
basically
in
infant
geologic
mapping
and
looking
at
Falls,
for
instance,
if
you
have
a
fault
and
very
often
you've
got
an
alteration.
That's
going
along
the
fault
and
faults
themselves
can
just
appear
in
the
magnetic
map,
so
you
get
a
structure,
that's
coming
in
like
that
and
then
suddenly
hill.
It's
there's
a
truncation
in
here.
A
The
one
thing
that
you'll
see
with
magnetic
data
is
that
they
will
often
do
post
processing
on
it
and
the
kinds
of
things
that
you
will
see.
For
instance,
here's
a
total
field
magnetic
anomaly
map
and
superimposed
on
here
are
the
geologic
structures.
So
you
can
see
correspondences
that
are
going
on,
but
sometimes
you
can
get
a
different
image
that
connects
with
you
geologically
just
by
doing
various
processings
on
it.
So
a
first
derivative.
We
talk
very
briefly
about
that.
A
So
that's
the
first
one
just
inference
from
images.
The
second
is
looking
at
simple
bodies
with
uniform
magnetization,
and
that
was
really
what
gave
rise
to
you
know
the
monopole
walls
and
you
know,
dykes,
various
kinds
of
intrusive
zones.
I
just
want
to
talk
a
little
bit
about
the
unexploded
ordnance
in
the
munition
this.
Just
that
I
mean
we're
not
only
working
on
it,
but
exactly
is
such
a
really
important
problem.
A
We
tend
not
to
see
so
much
of
it
in
the
context
of
North
American
work,
although
we
do
have
munition
sites
in
Canada
and
there
certainly
are
some
of
the
United
States,
but
we're
working
with
people
in
not
in
Europe
these
days,
Germany
places
that
have
been
bomb
very,
very
heavily
and
you
have
all
kinds
of
fun
residue
problems
that
are
better
go
through
them,
but
I
just
thought.
This
might
be
interesting
and
I
just
wanted
to
kind
of
tell
you
a
few
things
that
happen.
A
So,
if
you're
looking
at
a
number
of
sites
that
then
exist,
there's
actually
sort
of
like
3,000
sites
around
the
world,
maybe
tens
of
millions
of
acres.
So
it's
really
pretty
big
and
the
cost
of
these
cleanups
is
is
really
expensive,
and
you
can
appreciate
why
that
is
because,
if
you've
got
a
good
looking
for
something
that
can
explode,
you'd
have
to
be
very
careful.
Unexploded
ordinances
are
not
as
bad
as
landline.
Landlines
are
really
sensitive
to
touch
or
any
pressure
with
that,
but
yeah,
an
unexploded
ordnance.
A
You
can
likely
walk
over
it
right,
but
you
would
not
want
to
hit
that
with
a
plow
or
a
shovel
or
and
even
in
France.
If
you
look
at
the
statistics
for
grants
at
the
number
of
farmers
who
die
every
year,
because
they're
plowing
up
their
field
and
hit
some
ordinance
item,
you'll
find
it's
about
7
to
10
ppl
year
and
that's
and
those
are
bombs
from
you
know
like
the
First
World
War.
A
A
We
need
to
somehow
kind
of
recognize
the
problem
and
here's
here's
just
some
of
the
sites.
Well,
I
guess
this
is
most
of
the
sites
in
the
United
States,
but
each
of
these
dots
represents
actually
a
place
where
army
and
navy
people
have
been
trained
to
use
various
kinds
of
artillery,
and
when
you
think
that
a
lot
of
those
artillery
shells
you
only
between
90
and
ninety-five
percent
of
them
actually
explode.
A
A
Here's
here's
landscape,
for
instance.
This
is
a
place
we
actually
worked
on
here
at
kol
ave.
It's
a
sacred
Island
in
in
Hawaii.
It's
now
being
turned
back
to
Native
Hawaiians
in
the
process
of
doing
that
it
has
to
get
cleaned
up,
and
so
the
u.s.
army
decides.
Okay,
we
can.
We
can
clean
this
up,
it's
not
a
huge
island,
but
they
allotted
something
in
the
order
of
I.
Just
like
a
hundred
million
dollars
to
go
in
and
clean
up,
I
know
maybe
hundred
hectares
or
suffered
for
something
like
this
right.
A
So
three
years
later,
I
had
a
fifty-million-dollar
expand,
so
that's
like
150
million.
They
were
actually
twenty
percent
cleaned
up
and
the
problem
is
that
you
know
these
things
are
closest.
So
every
time
you
find
something
you
got
to
go
in
with
all
these
DoD
techs
and
be
very
careful
cordon
off
and
then
you're
scraping
the
dirt
of
waiting
a
little
tiny
shovel
and
trying
to
figure
out
what
you've
got.
A
And
then,
if
you
decide
that
it's
ordinance
item
then
another
who
comes
in,
they
could
have
a
cordon
off
the
area,
and
then
they
figure
out
what
to
do
with
it.
Usually
what
they
do
is
carry
these
very
carefully
over
to
some
central
region,
and
then
they
just
blow
the
whole
thing
up
just
one
time
or
sometimes
they'll,
just
pull
them
up
in
place.
A
Not
everything
you
find
is
the
eye
or
deciding
that
you're
looking
for
or
shoe
piece
of
rag
whatever
and
I
showed
you
this
before.
This
was
in
limestone
hills
in
Montana
I
like
this
picture,
because
it
really
sets
the
scene
right
here.
It's
just
like
when
you're
down
at
the
beach
looking
for
those
rods,
the
sand
is
the
same
everywhere.
Same
is
true
with
the
grass
just
you
have
no
idea
where
to
where
to
look.
A
So
you
have
you've,
got
to
do
some
kind
of
your
physician
and
help
you
up
and
you
could
do
as
I
said,
sort
of
manual,
stuff,
mag
and
flag,
but
honest
to
god.
If
you
do
mag
and
flag,
you
just
look
back
and
you
got
the
sea
of
flags
so
that
doesn't
help
you
I
mean
helps
you,
but
it's
kind
of
awesome,
so
you
gotta
do
some
digital
geophysics
and
now
we've
seen
it
soon.
As
I
said
before,
you
look
at
these
pictures
and
your
you
immediately
thought
those
are
dipoles
right.
A
We've
got
exactly
that
price
characteristic
and
there's
a
whole
bunch
of
these
things,
and
you
also
notice
that
other
flipped
around
on
this
guy's,
pointing
this
way
this
year,
is
here
they're
not
in
the
state
you're,
not
in
one
direction
and
they're,
not
in
the
direction
of
your
skill,
so
they've
gotta
be
remnant.
Me
magnetize,
you
just
with
your
iron
objects
when
you
actually
go
out
and
do
a
survey.
Sometimes
you
just
get
great
data
like
clues.
No
question
here
about
this
guy,
that's
a
little
bit
worse!
A
Sometimes
you
know
you
start
to
get
a
lot
of
kind
of
special
stuff
in
here
and
then
you
know
sometimes-
and
this
is
that
loads
more
often
than
not.
There
actually
is
an
ordinance
item.
That's
that's
buried
in
here,
but
you've
got
all
kinds
of
other
stuff.
You
could
see
that
this
might
be
a
bit
challenging
I'm,
trying
to
figure
out
where
the
there's
two
aspects
here.
One
is
to
recognize
the
item,
but
even
a
piece
of
fried
will
look
like
this,
so
you
actually
want
to
do
more.
A
You
want
to
do
more
than
just
recognize.
Oh
there's
something
there
because
now
you're
digging
up
a
whole
bunch
of
stuff
that
doesn't
really
need
to
be
dug
up
and
in
these
areas
where
there's
a
lot
of
munitions
that
are
exploded,
but
you
know
sometimes
there's
only
one
and
fifty
or
one
and
a
hundred
that's
actually
a
live
unit
munition
the
rest
are
all
just
junk
items.
So
we'd
like
to
be
able
to
characterize
a
little
bit
better.
A
What
these
guys
are
and
magnetics
actually
helps
us
electromagnetics
is
even
better
than
we
might
come
to
that
at
the
end,
but
even
from
electro
magnetics.
If
we
can
find
out
something
about
your,
maybe
the
strength
of
the
sky
as
well.
As
you
know,
orientation
might
help
us
out
a
bit
so
now,
you're
in
a
problem
that
that
looks
like
this.
We've
got
buried
in
the
earth,
an
unexploded
ordnance
that
really
just
looks
like
a
bar
magnet
and
it
has
arbitrary
position,
depth,
horizontal
location
and
it
has
an
arbitrary
orientation
and
a
strength.
A
You
can
start
to
get
the
idea
that
yeah
even
a
problem
with
maybe
a
half
a
dozen
parameters
is
not
one
hundred
percent
trivial,
so
we're
going
to
need
to
do
some
sort
of
more
sophisticated
analysis
to
work
with
this,
and-
and
this
is
what
what
we're
going
to
do-
and
this
is
what
is
done
in
virtually
all
of
the
geophysical
problems.
We've
got
something
here
that
we're
trying
to
to
to
find
model
and
we
have
to
predict
what
the
responses
are
going
to
be.
So
that's
what
the
app
did
right.
A
You
you
buried
a
prism,
put
an
inducing
field
in
it,
you
specified
the
susceptibility,
and
then
you
generated
the
data.
So
that's
often
called
the
forward
problem.
You're
see
violating
the
data,
but
we
want
to
do
is
extract
parameters,
and
that
means
we're
going
to
do
this
inverse
problem
and
try
to
somehow
get
take
these
data
and
come
back
to
a
representation
of
this
object.
A
So
that's
an
optimization
problem:
we're
not
going
to
go
through
the
details
about
how
to
do
that,
but
that's
pretty
standard
procedure
for
how
to
work
with
things,
and
this
is
kind
of
what
we
get
up.
So
we
start
here
with
the
data
and
now
we've
got
all
those
parameters,
so
we
adjust
them
these
the
program
adjust
them
until
we
get
like
a
best
fit
to
the
data,
and
then
we
look
at
the
difference
between
these
two
guys.
A
You
say:
oh
yeah,
that's
not
such
a
bad
notice,
the
scales
here
much
smaller
than
the
scale
up
there,
so
we
done
not
too
bad
a
job,
and
now
we've
got
the
parameters.
East
ignore
the
depth
and
moment
as
nuisance,
and
so
these
things
are
actually
useful
for
the
point
of
view.
First
of
all,
digging
where
it
is
and
later
on,
that
becomes
part
of
a
discrimination
analysis.
A
When
we
look
with
electromagnetics
to
help
us
decide
whether
that
item
is
likely
an
ordinance
item
and
needs
to
be
dug
up
or
whether
it
can
just
sit
in
the
ground,
that's
a
bunch
of
junk.
So
that's,
basically
the
essence
of
the
problem.
We've
got
magnetics,
we've
got
a
way
of
extracting
parameters
and
then
we
go
ahead
and
do
classification
and
as
I
step
a
little
later
do
the
key.
Yet
there's
a
there's
kind
of
an
interesting
story
which
I
hadn't
really
appreciated.
A
A
Ok,
so
the
Americans
actually
built
an
atomic
bomb
and
looked
at
they
go
over
Japan,
twice
Hiroshima
and
Nagasaki
to
devastating
effects,
but
there
was
a
real
race
on
to
generate
an
atomic
bomb.
The
Germans
had
kind
of
started
out
first,
and
they
have
some
ideas
before
they
even
did
their
initial
invasions
into
some
of
the
European
countries
and
they
progress
with
that
through
throughout
the
war,
but
it
kind
of
got
de-escalated
as
far
as
their
priorities.
They
were
having
technical
problems
and
it
turned
out
the
u.s.
actually
beat
them
to
it.
A
Nevertheless,
the
Germans
had
continued
to
develop
this
in
them
and
the
big
thing
with
an
atomic
bomb.
Is
you
got
to
take
this?
The
uranium
and
you
got
to
concentrate
it.
I
mean
this.
Is
the
big
deal
with
Iran
right
is
why
everybody's
still
concerned
about
centrifuges
and
their
ability
to
concentrate
and
rain?
If
you
make
it
concentrated
enough,
then
you
can
actually
make
it
into
off.
A
So
there
is
an
area
outside
of
Berlin.
It
was
in
town,
and
that
was
one
of
the
central
areas
where
they
were
trying
to
do
this
enrichment
about
three
weeks
before
the
end
of
the
war,
the
Germans
were
losing
the
Russians
are
coming
in
to
invade
Germany
the
US
realizes,
like
oh,
my
god.
The
Germans
have
got
this
huge
concentration
of
Technology
uranium.
A
Ok,
so
what
is
the
u.s.
do?
So
they
take
these
big
bombs,
five
hundred
thousand
pound
bombs-
and
this
is
the
part
that
I
didn't
know.
You
can
actually
have
delay
fuses
on
these
things,
so
you
can
draw
the
bomb,
but
it
can
be
such
that
it
actually
doesn't
detonate
for
a
certain
length
of
time
after
the
u.s.
bombarded
this
area
just
a
trance
number
of
bombs,
and
they
fuse
these
things.
A
A
It's
got
to
be
cleaned
up,
so
what
are
we
looking
at
we're
looking
at
bombs
there
about
500,000
pounds,
and
these
guys
are
dropped
in
from
gully
nilly,
and
here
is
kind
of
interesting.
Your
bomb
drops
it
funny
in
first
right,
but
we're
going
to
see
when
we
do
the
seismic
that
things
can
actually
refract
so,
depending
upon
your
what
materials
properties
as
something
is
coming
in
and
it
did
at
an
angle,
it
can
actually
go
to
bend
around.
So
it
turns
out
that
you
know
some
of
the
bombs.
A
Are
you
know
kind
of
in
like
sort
of
point
here
and
down,
but
other
guys
have
just
kind
of
got
a
trajectory.
They
went
down
in
and
they're
kind
of
completely
off,
so
they're
there
soon
you're
sitting
there
pointy
end
up
and
at
the
end
of
the
day,
you've
got
an
area,
that's
littered
with
these
ordinance
items.
Each
of
these
is
magnetic.
Each
of
these
has
got
a
remnant
magnetization,
and
each
of
these
is
in
some
crazy
directions
for
some
point
down.
Somebody
up
this
way:
that's
okay!
So
what
do
you
do?
A
The
basic
problem
is,
then
trying
to
find
these
guys
you're
trying
to
find
an
egg.
So
now
the
thing
is:
okay:
how
big
a
field
does
a
500-pound
arm
may
and
how
often
would
you
have
to
sample
the
earth
in
order
to
find
it?
So
it
turns
out-
because
these
guys
are
so
deep
that
you
can't
just
do
a
surface
measurement.
A
A
A
Okay,
so
that's
the
methodology.
We
just
blanket
the
area
with
holes,
every
two
point:
three
meters
and
gradually
sterilize
it
I
mean
holes.
You
think
takes
anybody.
Thousands!
Where
do
you
say:
John
awesome,
forty-seven
thousand
holes,
each
of
them
up
to
about
10
12
meters.
They
each
of
them.
We
put
down
a
magnetometer
each
of
them.
You
try
to
see
what
you
could
say
and
then
they
actually
did
find
the
number
of
them.
So
that
meant
a
few
bottles.
Okay,
but
that's
F,
I,
think
that's
an
interesting
story
for
watch
perspectives.
A
Yep
good
would
never
vote
I'm
drilling
into
yeah.
That's
the
first
one
right,
the
first
pretty
iffy,
so
you
drill
down
there.
But
then
now
I
feel
like--okay.
I
can
safely
scan
out
here
right.
So
you
know
I
will
hear
them.
Okay,
nothing!
So
I
could
go
two
meters
here
now
I
find
out
through
here
and
you
gradually.
A
So
the
yeah
so
I
think
the
point
about
that
is
really
interesting.
Is
that
the
simple
geophysics
that
we've
just
done?
Okay
actually
has
a
lot
of
relevance
even
in
practice
they
are
included.
We
do
things
that
are
much
more
complicated
but
you're
even
understanding
the
basic
principles.
He
couldn't
sometimes
go
long,
wait,
I.
A
I'd
like
to
turn
now
attention
to
the
next
level,
which
is
to
actually
think
about
in
converting
some
data.
So
this
is
the
diamond
mine
in
northern
Canada
and
all
these
pictures
are
courtesy
of
Dom
who
was
there.
He
did
all
the
processing
of
these
guys.
So
I'm
not
sure
if
you
know
that
Canada
is
very
prominent
in
the
diamond
exploration
and
diamond
production,
I
mean
anybody
did
who
did
not
know
that
Canada
was
a
prominent
person
or
country
and
diamond
okay.
A
So
there's
a
few
and
then
some
of
the
Canadian
diamonds
got
little
polar
bear
etched
on
them.
Just
to
tell
you
that
they're
Canadian
diamonds,
they
to
diamond
mines,
that
you
hear
about
our
okati
and
Diavik,
but
there's
a
whole
bunch
of
places
that
are
perspective
diamonds
side,
don't
know
whether
you
guys
do
that
and
George,
but
they
come
up
through
what
are
called
kimberlite
pipes.
So
these
are
pipes
that
you
know
connected
to.
A
You
know
the
mantle
they
might
come
up
from
you
off
a
couple
hundred
kilometers
depth
at
those
temperatures
and
pressures
diamond
is
actually
a
stable
form
of
carbon.
So
if
you
were
able
to
go
down
150
kilometers,
you
might
have
just
like
a
lot
of
diamond
there
right,
so
the
girl's
best
friend,
150
kilometers,
deep,
so
so
we
can
take.
You
can
take
magnetic
data
over
top
here.
So
this
is
this
vision.
You
see
these
lines
that
are
coming
in
here.
A
Those
are
all
dykes,
so
there's
our
magnetic
dykes
that
are
are
coming
in
through
it,
and
that
gives
you
some
idea
about
the
complexity
of
this
protonic
shield
area,
and
if
we
look
a
bit
more
closely
at
this,
this
was
the
observed
data
notice,
how
it's
going
to
kind
of
from
blue
to
yellow
ish,
so
that's
kind
of
like
a
regional
trend.
So
it's
big
scale
right
this.
A
You
know,
but
you
could
take
take
a
look
at
this
and
you
say
well,
let
me
try
to
find
a
regional
that
kind
of
matches
that
background
with
something
like
this,
but
that's
still
like
400
nano
teslas.
So
it's
pretty
big.
Take
this
track
bad!
You
end
up
with
this,
and
now
this
is.
This
is
more
like
the
magnetic
anomaly
map
that
you
would
really
try
to
to
infer.
A
You
can
see
the
dikes
are
coming
out
pretty
nicely
if
you
plot,
where
the
kimberlite
pipes
are
with
respect
to
the
dikes
you
see,
all
most
of
the
kimberlite
pipes
are
actually
connected
with
where
these
dikes
are
coming
in.
So
that's
kind
of
favorable
areas
for
prospectors,
so
even
just
know,
kind
of
knowing
where
ola
the
dikes
are,
would
step
forward
and
there's
their
all.
These
guys
have
different
names,
not
sure
how
they
go.
Scorpion
Zack
Brant
this
one
we're
going
to
look
at
is
misery
so
I.
A
Maybe
it
wasn't
all
that
happy
a
bit
for
somebody,
but
it's
kind
of
an
interesting
name
and
the
property
is
owned
by
bhp
billiton,
and
this
is
a
surface
map
of
what
it
looks
like
in
here
so
kind
of
like
a
3d
volume,
rendering
of
the
of
the
pipes
that
are
dard,
imma,
difference
and
kind
of
looks
look
something
like
that.
Okay,
this
was
all
done
by
drilling
the
lots
of
drill
holes
and
kind
of
gives
you
that
kind
of
a
picture.
So
now
we
come
over,
take
the
magnetic
data.
A
A
A
So
that's
kind
of
the
that's
kind
of
like
that
complicated
in.
So
we
have
the
three
part:
three
levels
just
looking
the
day
to
do
something.
Look
at
the
game
to
analyze
it
try
to
get
a
few
parameters.
Do
something
look
at
the
data
put
it
through
a
full
3d
inversion,
get
out
of
38
your
magnetic
anomaly,
earth
and
magnetic
susceptibility
and
make
your
interpretation.
A
A
Okay,
what
we
will
do
on
friday-
and
I
will
ask
you
to
take
a
look
at
the
gpg-
we're
working
very
hard
at
refactoring
and
we're
about
47
seconds
ahead
of
you
on
this,
but
you
can
take
a
look
at
the
gpg
and
especially
that
part
on
the
physical
properties.
So
that's
where
we
want
to
want
to
get
to
so
what
we're
going
to
do
now,
just
completely
switch
gears
we're
going
to
go
to
looking
at
elastic
properties.
A
So
this
means
shear,
modulus,
Young's,
modulus,
poissons
ratio,
these
types
of
things
and
we're
going
to
do
it
through
seismic
velocity.
So
you
had
one
in
one
component
of
that
first
lab
where
you're
looking
at
this
is
the
properties
needed
p,
wave
and
S
wave
velocity,
we're
gonna,
look
at
that
and
look
at
things
like
reflections
and
refractions
and
just
to
see
how
you
can
get
a
whole
lot
of
smooth
of
information
about
what
you
okay.
Thank
you
good.