(共16张PPT)
Unit
4
UNIT
4
NATURAL
DISASTERS
Watch
the
video
to
know
about
tsunami.
To
talk
about
the
safety
instructions
about
tsunami.
Discuss
on
the
relief
work
after
tsunami.
Tsunami
waves
can
strike
out
of
nowhere
and
cause
a
lot
of
destruction.
Scientists
study
and
track
tsunamis
in
order
to
warn
people
and
minimize
deaths.
Tsunami:
Killer
waves
What
is
tsunami?
A?tsunami?is
a
series
of
ocean
waves
that
sends
surges
(急剧上升)
of
water,
sometimes
reaching
heights
of
over
100
feet
(30.5
meters),
onto
land.
These
walls
of
water
can
cause
widespread?destruction?when
they
crash
ashore.
What
Causes
a
Tsunami?
These
waves
are
caused
by
large,
undersea
earthquakes
at?tectonic
plate
boundaries.
When
the
ocean
floor
at
a
plate
boundary
rises
or
falls
suddenly,
it
displaces
the
water
above
it
and
launches
the
rolling
waves
that
will
become
a
tsunami.
It
may
also
be
caused
by
underwater
landslides
or
volcanic
eruptions.
What
should
we
do
when
a
tsunami
hits?
Do
you
know
some
safety
instructions?
If
you
hear
tsunami
warning,
evacuate
at
once.
Go
as
high
and
as
far
as
you
can
–
at
least
to
a
spot
30
meters
above
sea
level
or
2
miles
away.
Take
your?emergency
kit.
Drop,
cover,
and
hold
on
to
protect
yourself
from
the?possible
earthquake.
Avoid
downed
power
lines
and
stay
away
from
buildings
and
bridges
from
which
heavy
objects
might
fall
during
an
aftershock.
Read
the
sentences
about
the
formation
and
effects
of
tsunamis.
Then
match
each
sentence
with
the
correct
picture.
A.
Tectonic
plates
push
together.
B.
A
series
of
waves
expands
in
all
directions.
C.
Whole
sections
of
cities
are
destroyed.
Decide
whether
the
statements
are
true
(T)
or
false
(F).
1.
There
are
few
warning
signs
just
before
a
tsunami
hits.
2.
A
tsunami
breaks
just
like
an
ordinary
wave
but
is
bigger.
3.
Scientists
at
the
Pacific
Tsunami
Warning
Center
monitor
the
earth’s
movements
24
hours
a
day
in
order
to
track
tsunami.
T
F
T
A
tsunami
wave
doesn’t
break
like
an
ordinary
wave.
Circle
the
correct
word(s)
in
each
sentence.
1.
An
earthquake
occurs
when
plates
below
the
earth’s
surface
push
together/pull
apart.
2.
Tsunami
waves
deep
at
sea
move
fast
and
rise
only
a
few/hundreds
of
feet.
3.
As
these
killer
waves
enter
shallow
waters,
their
speed
is
reduced/raised.
4.
Most
tsunami
damage
is
caused
when
the
waves
come
in
from/move
back
out
to
the
sea.
What
have
you
learnt
about
tsunamis?
I’ve
learnt
that
they
are
dangerous/
that
they
aren’t
noticeable
or
strong
until
they
hit
the
coast.
What
kind
of
help
do
you
think
people
who
have
suffered
from
a
tsunami
need?
They
need
food,
water,
shelter,
etc.
They
may
also
need
medical
help
and
emotional
help
if
they
have
lost
loved
ones.
Work
in
pairs.
Discuss
the
questions.
Let’s
watch
another
video
about
tsunami.
Write
a
passage
in
70
words
about
how
to
help
the
people
who
have
suffered
from
a
tsunami.
