Active volcanoes / Aktive vulkaner:

Rinjani, Indonesia  



The 2,376 m high Barujari pyroclastic cone, the most prominent post-caldera featur of Rinjani volcano,
was formed at the easter end of the oval-shaped Segara Anak caldera lake. This 1993 view from the
NE caldera rim shows a peninsula at the right formed by lava flows that entered the caldera lake in 1944 from
a vent NW of Barujari. The dark-colored lava flows on the left side of Barujari flowed north and south into
the lake during an eruption in 1966.

 

Rinjani volcano on the island of Lombok, Lesser Sunda Islands, rises to 3,726 m, second in
height among Indonesian volcanoes only to Sumatra's Kerinci volcano. Rinjani has a steep-
sided conical profile when viewed from the east, but the west side of the compound volcano
is truncated by the 6x8,5 km, oval-shaped Segara Anak caldera.

The western half of the caldera contains a 230 m deep lake whose crescentic form results from
growth of the post-caldera cone Barujari aqt the east end of the caldera. Historical eruptions at
Rinjani dating back to 1847 have been restricted to Barujari cone and consist of moderate
explosive activity and occasional lavaflows that have entered Segara Anak lake.

Thursday, October 7th, 2004
A new explosion happened to day and sent an ashcolumn 4.500 m up in the air.
Hikers are banned from climbing on the volcano, but no evacuation of villages yet.
From visual observations on 2-4 October 2004 ash explosions still continues and are sending
sent ash columns that rose to ~ 300-800 m above the summit. A grey, thick ash column drifted
to the North. Point of explosion was in North-East slope of Baru Jari volcano. Light material
from the peak felt down around the Baru Jari volcano. Every explosion was accompanied with
detonation sounds. No visible change over the Segara Anakan Lake meant that no water was
entering to the caldera. Interval time between explosions was in range between 5 to 160
minutes.

Saturday, October 2nd, 2004
The Volcanological Society of Indonesia (VSI) reported that the Rinjani volcano erupted
yesterday at 05:30 am.

Since the increasing of volcanic quakes on 5 September 2004, volcanic activities on Rinjani
continue increasing, and finally Rinjani was erupted on 1 October 2004 at 5.30 WITA

Activity volcanic visually was not detected from the post monitoring at Sembalun Lawang
cause of covered by caldera’s wall. Seismicities activities in Rinjani volcano prompted
increasing in volcanic quakes since 5 September 2004. There fluctuated in the range of 0-7
events per day. Increasing of tectonic quakes that tended to be increased since the last of
18 August 2004.

Tremor quakes were registered since 23, 24, 25 and 26 September 2004, in number of 6-36
per day with range of amplitude between 12 mm - 14 mm, duration between 94 - 1450 mm.

Based on increasing of hazards at Rinjani after explosion, the authoritieshas risen the Alert
level to III (Orange) since 1 October 2004 at 06.00 WITA.

As a result of the explosion, it’s recommended to stop climbing activities to Rinjani until
the situation going back to normal again. - whichs sound quite reasonable....



A 2 km high, double-topped eruption column rises above Barujari cone at Rinjani volcano on June 9, 1994,
in this veiw looking south across the steaming caldera lake with the Segara Anak caldera wall in the
background. A small pycoclastic flow can be seen descending from the crater, and the flanks of the cone
are steaming from still-hot deposits of a previous explosion. The 1994 eruption began on June 3 and lasted
until at least November.
Photo courtesy of Volcanological Survey of Indonesia, 1994



An ash-bearing eruption plume rises on June 30, 1994 above the summit crater of Barujari,
a pyroclastic cone on the floor of Rinjani's Segara Anak caldera. Steam rises at
the lower right from a lava flow that began erupting during the earlier stages of the eruption,
which began on June 3.
Photo courtesy of Volcanological Survey of Indonesia, 1994

 
The June 1994 eruption.
At 02:00 on June 3rd, 1994, Barujari cone
began erupting by sending an ash plume 500 m
high. On June 8th, press report described
emission of "smoldering lava" and "thick smoke",
as well as ashfallin nearby villages from an ash
cloud rising 1,500 m above the summit. Between
3rd and 10th of June, up to 172 explosions could
be heard each day from the Sembalun Lawang
volcano observatory (~15 km NE). During this
period, seismic data indicated a dramatic increase
in the number of explosions per day, from 68 to
18,720 (!). Eruptions were continuous at least
through 19th of June, with maximum ash plume
heights of 2,000 m on 9th to 11th.

The ash plume generally drifted SE, depositing up to 30 mm of ash on the island. Strombolian eruptions
ejected pyroclastic material > 2m in size as high as 600 m above the vent; this material fell in a restricted
proxiamal area around the cone and in the lake. Lava flows began on 8th of June and partially covered
previous lavaflows from Rombongan (in 1944) and Barujari (in 1966).

A series of aircraft warnings based on pilot reports and weather satellite images indicated much larger
plumes than suggestede by the ground observations. First an eruption at about 12:00 on June 7th
produced a long plume that caused a large number of aviation warnings. The plume, located on satellite
imagery, extended 120 km S of Rinjani and was beginning to disperse by 15:30. A pilot report at 16:45
indicated a "smoke" plume to 13,500 m altitude moving ESE, but by 23:45 the plume was indistinguish-
able on satellite imagery. The imagery showed a plume around 06:33 on the 8th of June, which extended
at least 83 km SE of the volcano. Aircraft were advised to avoid this area to an altitude of 10,500 m asl.

In apparent conflict with ground observations and satellite imagery observed by Australia meeorologists,
a GOES satellite image at 18:31 on June 9th, revealed a N-directed plume. This straight distinct plume
originationg from Lombok Island trailed N for 800 km (!) over SE Borneo, where it merged with a
dense cloud bank. The plume widened from ~59 km across at a point 100 km N of the island to 100
km across where it met the Borneo coast.

Pilot reports at ~12:00 on June 18th again confirmed an ash cloud SW of the volcano for a distance
of 80 km and an altitude of 10 km. The plume was consistently observed on the imagery during the
night of 18-19 June, but remained thin.

The eruption continued at least into early July.

 

 

 

 

 

 

 

 

 

 


Photograph of Barujari cone (left) and Rombongan dome (right) on November 21st, 1994,
with Segara Anak lake in the foreground. View is looking approximately SW from the NE caldera rim.

Courtesy of P.M.Vincent.



Text and photos on this page mainly from
Kimberly, P., Siebert, L., Luhr, J.F., and Simkin, T. (1998). Volcanoes of Indonesia, v. 1.0 (CD-ROM).
Smithsonian Institution, Global Volcanism Program, Digital Information Series, GVP-1.

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ANIMALS

over 250

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BIRDS

over 500

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FLOWERS

over 225
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SEALIFE
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