::Mount Krakatau Trekking - Lampung & Java::
Krakatoa or Krakatau or
Krakatao is a volcanic island in the Sunda Strait
between Java and Sumatra in Indonesia. The name is used
for the island group, the main island (also called
Rakata), and the volcano as a whole. It has erupted
repeatedly, massively, and with disastrous consequences
throughout recorded history. The best known eruption
culminated in a series of massive explosions on August
26-27 1883.
The 1
883
eruption ejected more than 25 cubic kilometres of rock,
ash, and pumice, and generated the loudest sound
historically reported: the cataclysmic explosion was
distinctly heard as far away as Perth in Australia
approx. 1,930 miles (3,110 km), and the island of
Rodrigues near Mauritius approx. 3,000 miles (5,000 km).
Near Krakatoa, according to official records, 165
villages and towns were destroyed and 132 seriously
damaged, at least 36,417 (official toll) people died,
and many thousands were injured by the eruption, mostly
from the tsunamis which followed the explosion.
The eruption destroyed two thirds of the island of
Krakatoa. Eruptions at the volcano since 1927 have built
a new island in the same location, called Anak Krakatau
(child of Krakatoa).
Origin and spelling of the
name
The
earliest
mention of the island in the Western world was on a map
by Lucas Janszoon Waghenaer, who labelled the island "Pulo
Carcata". ("Pulo" is a form of pulau, the Indonesian
word for "island".) There are two generally accepted
spellings, Krakatoa and Krakatau. While Krakatoa is more
common in the English-speaking world, Krakatau (or
Krakatao in an older Portuguese based spelling) tends to
be favored by Indonesians and geologists. The origin of
the spelling Krakatoa is unclear, but may have been the
result of a typographical error made in a British source
reporting on the massive eruption of 1883.
Theories as to the origin of the Indonesian name
Krakatoa include:
* Onomatopoeia, imitating the noise made by cockatoos
which used to inhabit the island.
* From Sanskrit karka or karkata or karkataka, meaning
"lobster" or "crab".
* From Malay kelakatu, meaning "white-winged ant".
There is a popular story that Krakatau was the result of
a linguistic error. According to legend, "Krakatau" was
adopted when a visiting ship's captain asked a local
inhabitant the island's name, and the latter replied "Kaga
tau" — a Jakartan/Betawinese slang phrase meaning "I
don't know". This story is largely discounted; it
closely resembles famous linguistic myths about the
origin of the word kangaroo and the name of the Yucatán
Peninsula.
The name is spelled Karata on a map drawn before 1708.
Pre 1883 history
Before the
1883
eruption, Krakatoa consisted of three main islands: Lang
('Long', now called Rakata Kecil or Panjang) and
Verlaten ('Forsaken' or 'Deserted', now Sertung), which
were edge remnants of a previous very large
caldera-forming eruption; and Krakatoa itself, an island
9 km long by 5 km wide. Also there was a tree-covered
islet near Lang named Poolsche Hoed ('Polish Hat',
apparently because it looked like one from the sea), and
several small rocks or banks between Krakatoa and
Verlaten. There were three volcanic cones on Krakatoa:
running South to North they were: Rakata (823 m), Danan
(445 m), and Perboewatan (also spelled Perbuatan) (122
m). (Danan may have been a twin volcano). Krakatoa is
directly above the subduction zone of the Eurasian Plate
and Indo-Australian Plate, where the plate boundaries
undertake a sharp change of direction, possibly
resulting in an unusually weak crust in the region.
416 AD event
There is no
geological evidence of a Krakatoa eruption of this size
around that time; it may describe loss of land which
previously joined Java to Sumatra across what is now the
narrow east end of the Sunda Strait; or it may be a
mistaken date, referring to an eruption in 535 AD, also
referred to in the Javanese Book of Kings, and for which
there is geological and some corroborating historical
evidence.
535 AD event
David
Keys
and others have postulated that the violent eruption of
Krakatoa in 535 may have been responsible for the global
climate changes of 535-536. Keys explores what he
believes to be the radical and far ranging global
effects of just such a putative 6th century eruption in
his book Catastrophe: An Investigation into the Origins
of the Modern World. Additionally, in recent times, it
has been argued that it was this eruption which created
the islands of Verlaten and Lang (remnants of the
original) and the beginnings of Rakata — all indicators
of early Krakatoa's caldera's size. However, there seems
to be little, if any, datable charcoal from that
eruption, even if there is plenty of circumstantial
evidence.
1600s
At least three
Dutch travelers reported that Danan and Perboewatan were
seen erupting in May 1680 and February 1681.
The 1883 eruption
In the years
before the
1883
eruption, seismic activity around the volcano was
intense, with some earthquakes felt as far distant as
Australia. Beginning 20 May 1883, three months before
the final explosion, steam venting began to occur
regularly from Perboewatan, the northernmost of the
island's three cones. Eruptions of ash reached an
altitude of 6 km (20,000 ft) and explosions could be
heard in Batavia (Jakarta) 160 km (100 miles) away.
Activity died down by the end of May. Also, to help the
eruption along, water seeped into the magma chamber and
created vast amounts of super-pressured steam. It had
been thought Krakatoa was 3 different volcanoes, but it
was actually just one with a huge magma chamber.
The volcano began erupting again around 20 July. The
seat of the eruption is believed to have been a new vent
or vents which formed between Perboewatan and Danan,
more or less where the current volcanic cone of Anak
Krakatau is. The violence of the eruption caused tides
in the vicinity to be unusually high, and ships at
anchor had to be moored with chains as a result. On 11
August larger eruptions began, with ashy plumes being
emitted from at least eleven vents. On 24 August,
eruptions further intensified. At about 1pm (local time)
on 26 August, the volcano went into its paroxysmal
phase, and by 2pm observers could see a black cloud of
ash 27 km (17 miles) high. At this point, the eruption
was virtually continuous and explosions could be heard
every ten minutes or so. Ships within 20 km (11 nautical
miles) of the volcano reported heavy ash fall, with
pieces of hot pumice up to 10 cm in diameter landing on
their decks. A small tsunami hit the shores of Java and
Sumatra some 40 km (28 miles) away between 6pm and 7pm.
Cataclysmic stage
On August
27,
the volcano entered the final cataclysmic stage of its
eruption. Four enormous explosions took place at 5:30
a.m., 6:42 a.m., 8:20 a.m., and 10:02 a.m., the last of
which was worst and loudest. Each was accompanied by
very large tsunamis believed to have been over 30 meters
(100 ft) high in places. A large area of the Sunda
Strait and a number of places on the Sumatran coast were
affected by pyroclastic flows from the volcano. The
explosions were so violent that they were heard 2,200
miles (3,500 km) away in Australia and the island of
Rodrigues near Mauritius, 4,800 km away; the sound of
Krakatoa's destruction is believed to be the loudest
sound in recorded history, reaching levels of 180 dBSPL
100 miles (160 km) away.[4] Ash was propelled to a
height of 50 miles (80 km). The eruptions diminished
rapidly after that point, and by the morning of August
28 Krakatoa was quiet.
"The Burning Ashes of
Ketimbang"
Around
noon on August 27, a rain of hot ash fell around
Ketimbang in Sumatra. Around a thousand people were
killed, the only large number of victims killed by
Krakatoa itself, and not the waves or after-effects.[5]
Verbeek and later writers believe this unique event was
a lateral blast or pyroclastic flow (perhaps traveling
over the floating pumice rafts), similar to what
happened in 1980 at Mt. St. Helens. The region of the
ashfall ended to the northwest of Ketimbang, where the
bulk of Sebesi Island offered protection from any
horizontal surges.
After eruptions
Small eruptions
continued through October, and continued to be reported
through February 1884 (although any after mid October
were discounted by Verbeek). In the aftermath of the
eruption, it was found that the island of Krakatoa had
almost entirely disappeared, except for the southern
half of Rakata cone cut off along a vertical cliff,
leaving behind a 250-meter-deep caldera.
Effects
The combin
ed
effects of pyroclastic flows, volcanic ashes and
tsunamis had disastrous results in the region. There
were no survivors from 3,000 people located at the
island of Sebesi, about 13 km from Krakatoa. Pyroclastic
flows killed around 1,000 people at Ketimbang on the
coast of Sumatra some 40 km north from Krakatoa. The
official death toll recorded by the Dutch authorities
was 36,417 and many settlements were destroyed,
including Teluk Betung and Ketimbang in Sumatra, and
Sirik and Semarang in Java. The areas of Banten on Java
and the Lampung on Sumatra were devastated. There are
numerous documented reports of groups of human skeletons
floating across the Indian Ocean on rafts of volcanic
pumice and washing up on the east coast of Africa, up to
a year after the eruption. Some land on Java was never
repopulated; it reverted to jungle and is now the Ujung
Kulon National Park.
Tsunamis
Ships as far away
as South Africa rocked as tsunamis hit them, and the
bodies of victims were found floating in the ocean for
weeks after the event. The tsunamis which accompanied
the eruption are believed to have been caused by
gigantic pyroclastic flows entering the sea; each of the
five great explosions was accompanied by a massive
pyroclastic flow resulting from the gravitational
collapse of the eruption column. This caused several
cubic kilometers of material to enter the sea,
displacing an equally huge volume of seawater. In the
town of Merak, a Tsunami 46 metres high destroyed the
little town. Some of the pyroclastic flows reached the
Sumatran coast as much as 25 miles (40 km) away, having
apparently moved across the water on a "cushion" of
superheated steam. There are also indications of
submarine pyroclastic flows reaching 10 miles (15 km)
from the volcano.
On a recent film and documentary, a research team at
Kiel University of Germany conducted tests of
pyroclastic flows moving over water. The tests revealed
that hot ash traveled over the water on a cloud of
superheated steam with the heavy matter precipitating
out of the flow, shortly after initial contact with the
water, to create a tsunami due to the precipitate mass.
Geographic effects
As a result of the huge amount of material deposited by
the volcano, the surrounding ocean floor was drastically
altered. It is estimated that as much as 18-21 km³ of
ignimbrite was deposited over an area of 1.1 million
km², largely filling the 30-40 m deep basin around
Krakatoa. The land masses of Verlaten and Lang were
increased, and volcanic ash continues to be a
significant part of the geological composition of these
islands. Poolsche Hoed ("Polish Hat") disappeared. A new
rock islet called Bootsmansrots ('Bosun's Rock', a
fragment of Danan) was left.
Two nearby sandbanks (called Steers and Calmeyer after
the two naval officers who investigated them) were built
up into islands by ashfall, but the sea later washed
them away. Seawater on hot volcanic deposits on Steers
and Calmeyer caused steam which some people mistook for
continued eruption.
The fate of Krakatoa itself has been the subject of some
dispute among geologists. It was originally proposed
that the island had been blown apart by the force of the
eruption. However, most of the material deposited by the
volcano is clearly magmatic in origin and the caldera
formed by the eruption is not extensively filled with
deposits from the 1883 eruption. This indicates that the
island subsided into an empty magma chamber at the end
of the eruption
sequence, rather than having been destroyed during the
eruptions.
Global climate
In the year following the eruption, average global
temperatures fell by as much as 1.2 degrees Celsius.
Weather patterns continued to be chaotic for years, and
temperatures did not return to normal until 1888. The
eruption injected an unusually large amount of sulfur
dioxide (SO2) gas high into the stratosphere which was
subsequently transported by high-level winds all over
the planet. This led to a global increase in sulfurous
acid (H2SO3) concentration in high-level cirrus clouds.
The resulting increase in cloud reflectivity (or albedo)
would reflect more incoming light from the sun than
usual, and cool the entire planet until the suspended
sulfur fell to the ground as acid precipitation
Legacy of the 1883 eruption
The 1883 eruption
of Krakatoa is among the most violent volcanic events in
modern times (a VEI of 6, equivalent to 200 megatonnes
of TNT — about 13,000 times the yield of the Little Boy
bomb which devastated Hiroshima, Japan). Concussive air
waves from the explosions travelled seven times around
the world.[8] The sky was darkened for days afterwards.
Sea waves caused by the eruption were recorded as far
away as the English Channel.[9] The explosion is
considered to be the loudest noise ever recorded to be
heard by humans
MOUNT CRACATOA - VOLCANO
TREKKING
Duration: 03 DAYS / 02 NIGHTS
Start / Finish: JAKARTA
Grade: Easy - Moderate
DAY 01: JAKARTA - CARITA BEACH
Upon arrival at Jakarta Airport, you will have drive to
Carita beach on the western overcoast Jakarta.This land
journey will takes 6- 7hours drive in normaly traffic
road condition. Stay Overnight at simple hotel in Carita
beach. (D)
DAY 02: CARITA BEACH - SERTUNG ISLAND "CAMPSITE"
Transfer to Sertung island by speedboat from Carita
beach. You will enjoy cross the sunda strait for about 3
- 4 hours through the Cracatoa island. You will have
stay overnight in tents at Sertung island as our
campsite. (B, L, D)
DAY 03: SUMMIT MOUNT CRACATOA - CARITA BEACH -
JAKARTA
On this morning, you will leave campsite by
speadboat across to the opposite island of the Sertung
island which "Sun of Cracatoa" situated, for trek to
summit. Return to Carita beach and transfer to Jakarta.
Stop at local restaurant in Carita enroute to Jakarta. (B,L)
Come and Discover Indonesia Islands with us!
