The relatively small , 1.731 m tall stratovolcano Kelut has a craterlake that has been the source ofsome of the
most deadly eruptions in Indonesia.
Kelut is on the island of Java, and its excact position is 7°93' S og 112°31' E.




More than 30 eruptions have been recorded from Gunung Kelut since 1000 AD. The ejection of water from the
crater lake during Kelut's typically short, but violent eruptions has created pyroclastic flows and lahars that have
caused widespread fatalities and destruction.

After more than 5000 persons were killed during an eruption in 1919, an ambitious engineering project sought
to drain the crater lake. This initial effort lowered the lake by more than 50 m, but the 1951 eruption deepened the
crater by 70 m, leaving 50 million cubic meters of water after repair of the damaged drainage tunnels.
After more than 200 deaths in the 1966 eruption, a new deeper tunnel was constructed, and the lake's volume
before the 1990 eruption was only about 1 million cubic meters.


The "Anak Kelud" as of December 6, 2007.
© CVGHM, Indonesia.

A team discovered an intense degassing of the lake floor in early July 2007. The echo soundings recorded at that time revealed that almost 70% of the lake floor was degassing.


In blue, the evolution of the total CO2 flux (normalized to the lake area :103,600m2) since 2001.

Lake temperature measured at depth (15 meters) in the middle of the lake is increasing continuously since August 8
as well as the conductivity of the lake waters. The colour of the lake waters changed rapidly in August and September
from the typical green to yellow and bluish.

Views of the successive changes in the color of the lake waters.
Photographs courtesy of Akhmad Solikhin and Khirul Huda (CVGHM).

23.januar 2001

Kelut har vist en økning i aktiviteten siden 19 januar, og alarmberedskapet er satt opp til GUL. Økningen førte bl.a.
til at temperaturen på lavainnsjøen steg og ligger tett oppunder 50°C. Vannstanden har også økt omkring 5 cm,
noe som kan skyldes at toppen er begynt å bule ut, ifølge tiltmetermålingene. 20 tektoniske skjelv forekom siste uke.

Efter det katastrofale utbruddet i 1919 hvor 5.110 mennesker ble drept,
er det laget flere slike tunneler i fjellet, for å holde vannstanden i kratersjøen
så lav som mulig. Ved senere utbrudd har dette ført til ferre dødsfall.

Eksplosjonen i 1990 tømte kraterinnsjøen, og produserte pyroklastiske
flommer som dro mellom 7 og 8 kilometer nedover.

Pyroklastiske flommer under utbruddet fra den 10.februar til
den 17.februar i 1990 ødela store jordbruksområder.

After the last eruption that occurred in February 1990, a new lake rapidly filled the crater of this volcano.
The lake is shallow with a maximum depth of 34 m and a volume of 2.1 million m3. A tunnel was drilled through
the crater wall in 1926 to drain the lake and keep its volume constant.

The composition of the lake is rather unusual for an active volcano and corresponds to a near-neutral pH (6-7)
relatively diluted water with a TDS of a few g.kg-1. Persistent degassing from subaqueous fumaroles and hot springs
discharging into the lake maintain water temperatures between 28-42°C, largely above the ambient temperature of 19°C.
This hot lake can be regarded as the subaerial part of an underground heated aquifer or hydrothermal system

Info after 2001 mostly from
http://www.ulb.ac.be/sciences/cvl/Kelud/cud_Kelut.HTM