on august 26 1883 one of the deadliest
eruptions in human history began
even if you do not live in indonesia
where this occurred you have likely
heard of the volcano which produced it
krakatoa
however this eruption in 1883 was not
the first or last caldera forming
eruption which this mountain has
produced
today the volcano is active once again
this video will discuss
this active volcano and mention what its
future hazards are
the krakatoa volcano can be found in the
indian ocean between the islands of
sumatra
and java specifically it is 158
kilometers west of jakarta
the krakatoa volcano exists in its
current location because it is located
on a destructive plate boundary where
the eurasian plate is colliding with the
indo-australian plate
the subducted crust from this collision
then melts and migrates upwards until it
erupts on the surface
creating a volcano due to the highly
frequent and explosive nature of
krakatoa's eruptions much of its
early geologic history remains a mystery
what we do know is that eruptions
initially began in the indian ocean at a
depth of about 100 meters
over time numerous effusive and
explosive eruptions caused krakatoa to
grow
until it finally reached the surface as
krakatoa was a strata volcano several
different
vents erupted over time and formed a
vast island
around 400 a.d the island had a surface
area of about 84 square kilometers of
which the highest point was 950 meters
then in 535 a.d a massive eruption began
this eruption create a several kilometer
high lava fountain and a tall plume of
ash
eventually the island collapsed into the
ocean in an event similar to its 1883
eruption generating a large tsunami
the caldera left by this eruption
created three distinct islands
afterwards no eruptions were recorded on
the islands for 350 years
then in 850 a.d krakatoa had once again
reached the surface and began erupting
with an intermittent eruption style
over the next several hundred years the
island continued to grow in size until
it was once again connected to ricotta
island which had been separated by the
535 eruption
by 1685 the island had four prominent
peaks the tallest of which was 813
meters in elevation
in early 1883 after 200 years of
dormancy the volcano showed obvious
signs of unrest
numerous large earthquakes originating
beneath the mountain in april
and may were felt as far away as
australia
then on may 20th a medium-sized eruption
began on the island and a plume of ash
was carried six kilometers into the
atmosphere
over the next three months explosions
from this intermittent ongoing eruption
were heard in jakarta
then at 1 pm local time on august 26 the
climactic phase of krakatoa's eruption
began a continuous eruption plume rose
from the island and a rain of hot
ash fell in the vicinity 15 hours later
at 5 30 am a large explosion was heard
it was not known at the time but the
northernmost cone on the island had just
exploded and collapsed into the ocean
this generated a 30 meter high tsunami
which devastated the region
at 6 44 am another large explosion
occurred which once again generated a
tsunami
then at 10 02 am the largest explosion
in human history was witnessed
with an equivalent to 200 megatons of
tnt
the island exploded and created a large
pressure wave
the sound from this explosion was heard
on three continents including areas in
beijing
east australia and east africa
subsequently pyroclastic flows raced
outwards from the island in every
direction
some of these traveled up to 80
kilometers away and reach the east coast
of sumatra
the scope of the eruption which had just
taken place was profound as
more than two-thirds of the island of
krakatoa had disappeared
then in 1927 ana krakatoa once again
reached the surface
thus continuing the violent life cycle
of this volcano
by 2017 the volcano had grown once again
to
338 meters in height then in late 2018
two-thirds of the volcano collapsed into
the ocean creating a large tsunami
since then no additional eruptions have
occurred
krakatoa is truly one of the most
dangerous volcanoes on the planet
its eruptions have produced almost every
single volcanic hazard which i have
covered throughout this series
however the most deadly of its hazards
are tsunamis which will occur again
through either another landslide or
another caldera forming eruption i hope
that you enjoyed this video
if you would like to request a specific
topic please leave a comment below