1   Assessing  volcanic  hazards   Deciding  where  to  live  requires  careful  consideration.    An  overriding  factor  is  whether  a   place  is  safe.    In  this  exercise  you  will  investigate  a  volcanic  island  to  determine  what   types  of  eruptions  have  occurred  and  what  places  have  the  lowest  and  highest  risk.     Goals:     • Observe  the  physical  characteristics  of  the  volcano  and  the  rock  types  around  it   • Use  your  observations  to  determine  what  type  of  volcano  is  present  and  how  it   would  likely  erupt   • Assess  the  potential  for  volcanic  hazards  in  different  parts  of  the  island  and   determine  the  least  dangerous  place  to  live     Grading:   Point  allotments  are  given  for  each  question.    There  will  be  no  partial  credit.    Your   statements  will  be  graded  on  quality  of  explanation.    Statements  must  be  supported  by   scientific  evidence  given.         Volcano  Erupts!    (a  newspaper  account  of  an  imaginary  volcano)     The  Summit  volcano  began  erupting  in  early  September  of  1952,  and  dozens  of   small  eruptions  have  occurred  since  that  time.    For  10  years  before  the  1952  eruption,   residents  of  the  area  observed  plumes  of  white  steam  rising  from  the  summit  of  the   crater.    In  the  summer  of  1952,  local  inhabitants  reported  an  increase  in  the  output  of   steam,  an  increased  smell  of  sulfur,  and  a  series  of  small  earthquakes.         The  first  eruption  was  a  single  explosive  burst  that  lasted  about  three  hours   and  that  was  accompanied  by  clouds  of  ash  that  rose  kilometers  into  the  air.    Heavy   ash  fell  around  the  volcano,  and  a  light  dusting  of  ash  was  reported  on  adjacent   islands  up  to  20  kilometers  away.    The  eruption  melted  snow  and  ice  high  on  the   crater,  forming  a  mudflow  that  moved  along  stream  channels  and  inundated  many   areas  in  valleys  downstream  from  the  volcano.    After  the  main  eruption  a  lava  dome   started  growing  in  the  crater.       All  subsequent  eruptions  have  been  smaller  and  of  a  different  style.    They  have   been  similar  to  one  another.    In  each  eruptio ...

1. 1
Assessing
volcanic
hazards
Deciding
where
to
live
requires
careful
consideration.
An
overriding
factor
is
whether
a
place
is
safe.
In
this
exercise
you
will

2. investigate
a
volcanic
island
to
determine
what
types
of
eruptions
have
occurred
and
what
places
have
the
lowest
and
highest
risk.
Goals:
• Observe
the
physical
characteristics
of
the
volcano

3. and
the
rock
types
around
it
• Use
your
observations
to
determine
what
type
of
volcano
is
present
and
how
it
would
likely
erupt
• Assess
the
potential
for
volcanic
hazards
in
different
parts

4. of
the
island
and
determine
the
least
dangerous
place
to
live
Grading:
Point
allotments
are
given
for
each
question.
There
will
be
no
partial
credit.
Your
statements

5. will
be
graded
on
quality
of
explanation.
Statements
must
be
supported
by
scientific
evidence
given.
Volcano
Erupts!
(a
newspaper
account
of
an
imaginary
volcano)

6. The
Summit
volcano
began
erupting
in
early
September
of
1952,
and
dozens
of
small
eruptions
have
occurred
since
that
time.
For
10
years
before
the
1952
eruption,
residents
of
the
area
observed

7. plumes
of
white
steam
rising
from
the
summit
of
the
crater.
In
the
summer
of
1952,
local
inhabitants
reported
an
increase
in
the
output
of
steam,
an
increased
smell
of
sulfur,
and
a

8. series
of
small
earthquakes.
The
first
eruption
was
a
single
explosive
burst
that
lasted
about
three
hours
and
that
was
accompanied
by
clouds
of
ash
that
rose
kilometers
into
the
air.

9. Heavy
ash
fell
around
the
volcano,
and
a
light
dusting
of
ash
was
reported
on
adjacent
islands
up
to
20
kilometers
away.
The
eruption
melted
snow
and
ice
high
on
the

10. crater,
forming
a
mudflow
that
moved
along
stream
channels
and
inundated
many
areas
in
valleys
downstream
from
the
volcano.
After
the
main
eruption
a
lava
dome
started
growing
in
the
crater.

11. All
subsequent
eruptions
have
been
smaller
and
of
a
different
style.
They
have
been
similar
to
one
another.
In
each
eruption,
a
cloud
of
ash
and
rocks
moves
rapidly
downhill.

12. After
each
eruption,
geologists
noted
that
one
side
of
the
dome
in
the
crater
had
collapsed
into
a
pile
of
ash
and
rocks.

13. 2
Instructions
Write
your
answers
on
the
map
where
appropriate.
Other
answers
should
be
recorded
on
the
back
of
the
map.
You
may
use
your
notes
and

14. the
textbook.
A. (5
pts)
Read
the
newspaper
account
of
this
volcano’s
eruption
history.
On
the
diagram,
put
the
eruption
events
in
order
from
first
to
last:
• Lava

15. dome
growth
• Lava
dome
collapse
and
pyroclastic
flows
• Steam
eruptions
• Lahar
• Sub-­‐Plinian
eruption
• Small
earthquakes
accompanied
with
sulfuric
fumaroles
(gas
emissions)
B. (1
pt)
What
type
of
volcano
is
this?

16. (write
on
the
map)
C. (3
pts)
Label
the
parts
of
the
volcano
on
the
diagram.
• Crater
• Lava
dome
• Flank
(the
sides
of
the
volcano)
D. (3
pts)
Label
the

17. rocks
1,
2,
&
3
with
the
proper
rock
types
• Dacite
• Old
pyroclastic
flow
deposits
• Young
pyroclastic
flow
deposits
E. (3
pts)
Assess
how
each
volcanic
feature
contributes
to
the
hazard
potential

18. in
different
parts
of
the
island.
On
the
map,
draw
boundaries
around
and
label
those
areas
that
have
high,
medium,
or
low
hazard
potential
compared
to
the
rest
of
the
island.

19. The
differences
between
the
three
hazard
zones
will
be
fairly
subjective.
Use
your
best
judgment
and
be
consistent.
a. To
draw
boundaries,
divide
the
island
into
three
parts
emanating
from
the
summit

20. of
the
volcano
(like
slicing
a
pie).
Label
each
part
with
its
hazard
risk
–
high,
medium,
or
low.
F. (3
pts)
Write
a
statement
that
supports
your
choices
of
high,
medium,

21. and
low
hazards.
G. (1
pt)
Identify
the
area
you
consider
to
be
the
safest
place
to
live
with
an
X
on
the
map.
When
choosing
between
two
sites
that
are

22. equally
safe,
you
may
consider
other
factors,
such
as
the
scenery,
whether
the
sites
are
level
enough
to
build
on
safely
or
easily
accessible,
and
whether
they
are
subject
to
storms,
landslides,
floods,

23. and
other
natural
hazards.
H. (1
pt)
Write
a
statement
that
supports
your
choice
of
the
safest
place.
Name: ______________________________ Sec: ________
Rock 2 is hard igneous rock
that contains pumice and
ash
Rock 3 is composed of loose
pumice and as deposited in
a low lying area
Rock 1 is composed of

24. F1. High hazard zone explanation:
F2. Medium hazard zone explanation:
F3. Low hazard zone explanation:
H. Safest Place (marked with an X on your map):