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Eruption Story of Rinjani Mountain
Indonesia, 3726m
The
Story of Rinjani Mount Lombok,
3726m asl. Remember the time
before 2013, when the
volcano-interested world was
still guessing at what might
have caused that 1257 indelible
SO2 trace deep in the pristine
Antarctic ice sheet? Well,
scientists didn’t just guess but
worked out (and a paper was
published in 2013) that there
was enough evidence for a
caldera-forming VEI 7 eruption
in Samalas (today Rinjani
Volcanic Complex on
Lombok/Indonesia) to have been
the culprit. Imagine the scale
of that eruption: its magnitude
was 8 times more powerful than
Krakatoa’s and double that of
Mount Tambora, so it was one of
the largest Holocene eruptions
globally. Following the findings
of 2013, extensive studies on
this volcano were conducted by
Indonesian and international
scientists, and it was proposed
to preserve some areas on Lombok
as a geologically important
historic district. Tephra of
this eruption covers much of
Lombok, 35 to 40m high in
places. The ash is said to have
travelled around the world and
caused widespread climate
problems, leading to crop
failures and starvation in the
following years. This assumption
is based on many geological,
geochemical and petrographical
comparative data as well as on
points in history as the
collapse of the Kingdom of
Lombok in the 13th century and
the discovery of bones in a mass
tomb in London which could be
dated to 1258.
1257 – This eruption has
destroyed most of the edifice of
Samalas, leaving a caldera, now
filled with the water of Lake
Segara Anak. With time and
further volcanic activity a new
vent opened in the caldera floor
which became the pyroclastic
cone now called Baru Jari, son
of Rinjani. The cone rises about
370 m above the caldera lake,
and along with flank vents and
lava flows forms now a large
peninsula jutting westward into
the lake. All historical
recorded eruptions since 1847
have been restricted to this
Barujari cone and consisted of
moderate explosive activity and
occasional lava flows that have
entered Segara Anak lake.
1944 – An eruption produced the
Rombongan lava dome on the NW
flank of Gunung Barujari. It was
the source of the lava flow that
extends to the NW into the
Segara Anak caldera lake.
Rumblings and thick smoke with
nighttime incandescence began on
December 25, 1944. There was
heavy ashfall for 7 days,
destroying crops and houses
outside the caldera.
1966 – Following an earthquake
on March 28, explosive eruptions
formed a new small cone that fed
the lava flows, which eventually
covered a 600 x 1700 m area.
This eruption produced the
extensive barren lava flows that
still can be seen extending N
and S from the Bajuwari cone
into the caldera lake.
1994 – This eruption, the only
one marked VEI 3, went from
June-October. A glassy bomb from
this eruption was a basaltic
andesite (55% SiO^2); the two
previous eruptions (1944 and
1966) were basaltic. Lake
temperatures in April 1994 were
31°C close to the active
Barujari cone and 20°C on the W
side; temperatures on 9 October
1994 were 36 and 31°C,
respectively. Declining lake
levels were noted on 9 October
(~3 m drop). On 3 November, a
cold lahar from the summit area
traveled down the Kokok Jenggak
River. Thirty people from the
village of Aikmel who were
collecting water from the river
were killed; one person remained
missing. No damage to the
village was reported. Local
volcanologists noted that
additional lahars could be
triggered by heavy rainfall.
2004-2005 – Fluctuating seismic
activity and visual observation
conditions made it difficult to
determine actual eruptions but
in October 2004 Rinjani clearly
erupted, causing authorities to
immediately raise the hazard
status to Alert Level III.
A 10 June 2009 FLIR thermal
camera image of Rinjani's
Barujari cone and Segara Anak
lake. A thermal plume of hot
lake water was drifting from the
lava entry points. Temperature
scale is for lake waters. Photo
by R. Campion.
A 10 June 2009 FLIR thermal
camera image of Rinjani’s
Barujari cone and Segara Anak
lake. A thermal plume of hot
lake water was drifting from the
lava entry points. Temperature
scale is for lake waters. Photo
by R. Campion.
2009 – During May and June,
although the volcano was
frequently obscured by fog,
people still saw impressive
eruptions from the observation
post at Sembalun Lawang. They
noted continuous eruptions with
ejected glowing material
reaching 200 m in height above
the vent, and thrown laterally
out to a radius of 500 m from
the summit. A great amount of
ash, cinders, and incandescent
material fell into the caldera,
while smaller fragments were
blown away. – Same year, about
the lake: The lake is neutral
(pH: 7-8) and its chemistry
dominated by chlorides and
sulfates with a relatively high
concentration of total-dissolved
solids (TDS: 2,640 mg/L). This
unusually high TDS value and
lake surface temperatures
(20-22°C), well above ambient
temperatures (14-15°C) for this
altitude, reflects a strong
input of hydrothermal fluids.
Numerous hot springs are located
along the shore at the foot of
the Barujari cone. Bathymetric
profiles showed several areas
with columns of gas bubbles
escaping from the lake’s floor.
October-November 2015
Although, officially, the
eruption began on 25 October,
this photo (right) is labelled
“The first eruption of Mount
Baru Jari (23/10)”, which, if
true, would indicate that the
eruption had already begun at an
earlier time. In an later
article of that newspaper it was
said: “Together with some of the
photographers and other
climbers, Imran was in the last
group of the day (Friday 23/10)
who climbed Mount Rinjani“. –
Another indication that the
eruption might have begun
earlier is, IMHO, in the PVMBG
report: “In the span of 1 to 22
October 2015: Recorded 17 events
Tremor with maximum amplitude of
2-12 mm and quake length of
10-120 seconds, 13 events
Earthquake Low Frequency (LF), 3
events volcanic earthquake
Shallow (VB), 3 events Volcanic
Earthquake In (VA), 4 Local
Tectonic earthquake occurrence
(TL) and 10 events Far Tectonic
earthquake (TJ)”.
25 Okt. 2015 – Gunung Rinjani
National Park Authority
suspended the activity of
climbing Mount Rinjani on Sunday
around 10:45 pm. The
volcanologist at the Post
Rinjani said that the eruption
of Mount Barujari was still
relatively small. The alert
level has been raised from 1 to
2 (alert) later that day, and a
restriction zone of 3 km from
the caldera was implemented.
Officers of Mount Rinjani
National Park evacuated hundreds
of hikers and climbers of Mount
Rinjani to a safe place clear of
poisonous gas from the eruption.
Forest fires in the southern
caldera area 23/10.
26 Oct. 2015 – That day, Hindus
gathered at the temple
Jagadnata, solemnly sang a song
of Earth Atonement, and recited
prayers and sacred dance to the
world Dewanata. This ritual is
the beginning of the Cultural
and Natural Pekelem Sudha, a
Hindu prayer procession with
participants arriving from Bali,
Java, and Borneo as well. This
big ceremony for Hindus is
conducted every five years on
the island of Lombok. For three
days they will climb Mount
Rinjani to reach Lake Segara
Anak, which is believed to be
the spiritual center in the Land
Sasak.
The sanctity of Mount Rinjani
was believed by Hindus since the
sixteenth century: At that time,
faced with a long drought that
resulted in deaths and disease,
the King Anglurah got the
whispers to perform Yajna Earth
Sudha and Pekelem on Fifth Month
Moon at Lake Segara Anak Gunung
Rinjani. Miraculously, after the
ritual was held, it rained on
the earth and brought back the
blessings of health for the
local community. Since then, the
Hindus in Lombok continued this
ceremony until now. – What a
nice background to such a
ceremony an erupting volcano is!
31 Okt. 2015 – Activity has
increased again on Saturday
morning, with at least ten
explosions and plume hights up
to 700m, moving N.
3 Nov 2015 – Authorities have
prepared several scenarios for
evacuation, there are 40,000
residents living around the
mountain! Also, the previous day
first reports came in from
pilots of local aircraft that
the heat from the eruption and
first ash particles disturbed
the air space over Lombok. Since
this morning activity of Rinjani
is increasing, accompanied by
tremors which tend to rise to
amplitude of 22.5mm, dominant 12
mm. A total of seven villages in
North Lombok are affected by
volcanic ash, with the ash
plumes going now up to a hight
of 1300m. Face masks have been
distributed and extra personnell
is making sure that nobody
enters the restriction zone of
3km.
4 Nov. 2015 – The ash plume from
Rinjani is travelling west and
closing one airport after the
other on the neighboring
islands. According to Dr. Devy
Syahbana Kamil, since November
2, seismic tremor was recorded
continuously and the eruption
energy increased significantly.
Visual observations indicate
strombolian explosive eruptions
and lava flows from the crater.
Height of the eruption column
was at a maximum of ~2,000 m
above the crater or 3400 m
a.s.l.
Eruption of #Rinjani volcano as
photographed by PVMBG team near
the caldera's rim early morning
of Nov. 4, 2015
5 Nov. 2015 – Dr. Surono, expert
for Disaster mitigation,
estimates that the eruption of
Mount Rinjani will not be very
explosive. “Mount Rinjani no
longer has significant power to
make an explosive eruption,” he
said in Yogyakarta on Thursday,
because “after the latest
eruptions the magma plumbing
system is already open. In
addition, the volume growth of
the lava dome of Mt. Rinjani
also tends to lower the maximum
flow rate which reaches 18 m^3/s
(3 Nov. 2015), unlike in Mt.
Merapi where the growth of the
lava dome reached 38 m^3/s in
2010”.
The results of MODIS data
processing showed that the magma
heat flux increased since two
days ago to the present. The
maximum rate of discharge of
lava to the surface ranges from
1-18 m^3/s with a rising trend.
The primary potential hazard at
this time is in the form of lava
flows and pyroclastic fallout
within a radius of 3 km and in
all areas in the Rinjani
caldera. Indirect hazards may
include flash floods in the
river if pyroklastic materials
and lava flows fill up the lake
as happened in the eruption of
2009.
06 Nov. 2015 – The latest report
for 12:00 to 18:00 pm:
Visual: The weather was
overcast, winds calm, clear
mountain-0III fog. Air
temperature 26°C, humidity 84%.
Thick white to gray plume,
height ± 2500 m leaning to the
south. Earthquake: Tremor
constantly Amax: 3-44 dominant
16 mm.
Conclusion: G. Rinjani Level 2
(Alert). Recommendation: No
public activity in all areas in
Rinjani caldera and in a 3 km
radius of the crater G.
Barujari. Communities are to
prepare masks in anticipation of
volcanic ash. Communities that
are around the river to be aware
of potential flooding [White
crowing Floods] if an increase
in the water level of the lake
occurs due to eruption material
filling in. source by
https://volcanohotspot.wordpress.com/2015/11/06/baru-jari-son-of-rinjani-and-samalas-a-time-line/
Lombok Rinjani Trekking
Fax Number : 0370 - 692035
Whatshapp : +62
081339522032
Mobile Number : +62
081803684982
Website :
http://www.lombokrinjani.com
e-mail address :
lombokrinjani@gmail.com
Jl.Tenggiri no.15 BTN
Green Valley Senggigi - Lombok, Indonesia
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