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Masahiro Aoki
Mineral Resources Dept., Geological Survey of Japan, Higashi 1-1-3, Tsukuba 305, Japan,
e-mail: aoki@gsi.go.jp
ABSTRACT: A unique event- an underwater eruption in
the Karymskoe fresh-water lake (in the Academia Nauk caldera)- was studied by
scientists from the Institute of Volcanology. Geomorphologic, hydrological,
hydrochemical and hydrobiological investigations were conducted. This publication
contains the general first results of the investigation of this phenomenon.
1 INTRODUCTION
2 DESCRIPTION OF THE SUBMARINE ERUPTION
3 AN ESTIMATE OF HEAT RELEASE
4 CHANGES IN THE LAKE WATER COMPOSITION
The lake became one of the largest reservoirs of acid water in the world.
The general salt content in the lake water increased significantly. We calculated
the change in overall salt reserves in the lake, using data on water composition
before and after the eruption (table 2). 6 CONCLUSION
7 ACKNOWLEDGEMENTS
REFERENCES
Fazlullin S.M., Shuvalov R.A., Karpov G.A.,
Ushakov S.V. Subaqueous Eruption from
Karymsky Lake (Kamchatka) and its Effects
//Crater Lakes, Terrestrial Degassing and Hyper-
acid Fluids in the Environment. Chapman
Conference. Abstracts. September 4-9, 1996 Crater
Lake, Oregon. 1996. P. 15.
In the beginning of 1996 on Kamchatka a simultaneous eruption from two
volcanic craters, located six kilometers from one another, was observed. One
of them was in the crater of Karymsky volcano, while the other was in the northern
part of Karymskoe caldera lake. As a result of the eruption an accumulated
volcanic structure was formed in the northern part of the lake.
Investigations permitted the determination of the characteristic peculiarities
of the lake's post-eruption morphometry. A map of depth-contours in the lake
and crater, formed in the lake's northern part, was constructed (fig. 1).
Microelement composition analysis of water samples was conducted under the leadership
of Dr. Aoki of the Geological Survey of Japan. Macroelement composition was
determined in the chemical Laboratory of the Institute of Volcanology.
The eruption was proceeded by an increase in seismologic activity, beginning
in April, 1995. On December 31, 1995 at 19:26 local time an earthquake with
magnitude 5.8 occurred in Kronotsky Bay, which is located 50-60 km north-east
of Karymsky volcano. On January 1, 1996 at 20:57 an earthquake of magnitude 5.2
was registered near Karymsky volcano and at 21:57 an earthquake of magnitude 6.9
was registered 25 km to the south of Karymsky volcano (Fedotov S.A., 1996).
Over the next few days an earthquake swarm with magnitude > 5.0 was registered
in this zone. Near midnight on January 2, 1996 an eruption began in the crater
of Karymsky volcano and after 14-15 hours an underwater eruption commenced in
the northern part of Karymskoe lake. According to available information (Fazlullin
et.al, 1996, Karpov et al, 1996) the underwater eruption in the Karymskoe lake
began on January 2, 1996 between 14:00 and 15:40. It has been established that
the surface of the lake was free of ice at midday on January 2, while one week
earlier an ice layer was observed.
Aerial observations were conducted at a distance of 5-7 km between 15:40
and 16:20. A gas-ash trail rose up to 3 km and spread to the south-east, in the
direction of the Pacific ocean. Ash fall from the trail covered hundreds of
square kilometers. Simultaneously, in the northern part of the Academia Nauk
caldera, steam and gas loaded with a dark material (presumably, volcanic ashes
and lake sediments) rose in columns above the lake with a frequency averaging
once every 5-6 minutes(Karpov, 1996). In the process of the volcanic expulsions
a cupola-like cloud with a diameter of 200-300 m formed. Over the course of
several seconds the cloud changed its form. A basic wave in the form of a
taurus-shaped cloud spread to all sides from the eruptive center. Its top edge
was approximately 100m high. At the same time, a white gas-steam plume extended
upward 7-8 km from the eruptive center. Each series of underwater explosions was
accompanied by the formation of waves on the surface of the lake, some of which
reached several meters in height. The energy of one explosion, as calculated
by S.A. Fedotov (Fedotov 1996) according to the maximum height of the gas-ash
clouds, reached 1014 J. As a result of the eruption, a flood occurred in Karymsky
River, which flows out of the lake. A significant part of the caldera of Karymsky
volcano, adjacent to the river valley, was covered in a mud flow.
On January 3, explosive activity in the lake stopped. According to our
calculations, the activity lasted a total of 12-14 hours. The entire surface
of the lake steamed, and the steam reached a height of 800-1000m. In the northern
part of the lake, a beach of erupted material was formed, creating a new coast
line. Plumes of fumarolic gas rose from several vents on the surface of this beach.
Characteristics of the lake, based on observations of Sept.,1996
----------------------------------------------------------------
Length, m 4050
Maximum width, m 3750
Average depth, m 47
Maximum depth, m 61-62
Area of the water surface, km2 9.8
Coast line, km 12.5
Volume of the lake water, million. m3 460.6
Volume of water in the new crater, million. m3 5.1
Volume of the new volcanic structure, million. m3 60.1
Angle of the lake sides, degree 12-15
Average angle of the crater, degree 12
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Water level in the lake changed by several meters. The flow of the
Karymsky river from the lake was blocked by a dam, formed from erupted material.
Several tens of square kilometers of land about the lake was covered by material
brought by polluted rain, formed from lake water and eruption products. At a
distance of several hundred meters from the center of the underwater eruption,
impressions of various size, formed by falling bombs and other material, were
noted in the snow (Karpov, 1996). The waves created by the eruption removed the
snow cover on the shoreline, in places up to 15-20m above its surface. In many
places on the coast land slides and an absence of top soil were noted. The
inner slope of the Academia Nauk caldera, adjacent to the zone of the eruption,
suffered most of all. Tens of thousands of cubic meters of soil were eroded by
water. Intensive influence of materials from the underwater eruption damaged
plant cover over an area of several square kilometers, covering everything with
a layer of mud. The underwater eruption was a catastrophe for the lake’s biota.
The enormous waves, along with the sharp change in chemical composition and
water temperature, lead to the death of practically all life in the lake.
In order to calculate the amount of heat energy released during the course
of the underwater eruption, we used the vertical temperature distribution and
hydrochemical characteristics of early May, 1996. Persistent stratification
existed in practically the whole lake, excluding the new, water-filled crater.
An analysis of the particularities of the vertical temperature distribution and
mineralization in the lake showed that the water layer below the thermocline
formed as a result of the January eruption, and has undergone little change
since then. According to our calculations, the underwater eruption released
more than 11.8x1015 J of heat over the first two days of the eruption.
As a result of the underwater eruption, the hydrochemical characteristics
of Karymsky Lake changed drastically over the course of several hours
(table 1).
Table 1. Water composition in Karymsky Lake in various years (before and after the eruption) in mg/l
-----------------------------------------------------------------
elements 1 2 3 4 5 6 7
H+ 0,58 0,6 0,62 0,64
NH4 0,2 0,2 0,2 0,2 0,0 0,0 0,05
Na 65,3 64,4 73,0 64,6 14,2 10,4 322,0
K 6,6 6,7 6,6 6,6 1,7 1,6 23,5
Ca 64,0 64,0 63,2 63,2 3,6 1,6 4,8
Mg 18,9 19,3 18,4 18,4 3,16 0,5 0,2
Mn 1,94 1,94 1,92 1,92
Fe3+ 6,1 6,1 6,1 6,1
Al3+ 4,9 4,9 4,9 4,9 d.l.
Cl 40,5 39,0 38,3 37,6 12,0 8,5 422
SO4 374,0 374,0 374,0 374,0 5,4 3,8 11,5
HCO3 34,2 35,1 95,8
F 1,7 1,76 1,74 1,84 no det.
H3BO3 2.42 2.29 2.00 2.17 1,2 ** 52,4
H4SiO4 ð 190,0 194,0 192,0 192,0 57,6 45,0 208,0
pH 3,28 3,25 3,22 3,20 7,2 7,05 9,45
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notes: water samples from the lake (1- surface, 2- bottom) and in the new crater (3- surface, 4- bottom) taken in May 1996, 5- water from the lake (09.10.85), 6 - (19.06.85), 7- (20.08.93);
In samples 1- 4 Fe2+ concentration was less than 0.5 mg/l, and in the other samples none was detected.
(n.d. - not detected, d.l. - detection limit)
Table 2. Total reserve of chemical elements in the water of Karymsky Lake before
and after the eruption (in tons).
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Year Ñl SO4 HCO3 Na K Ca Mg Al Fe Mn Zn Cu
1993 11228 2530 11598 7380 442 3163 316 0.1 1.17 0.3 2.32 0.01
1996 24460 216730 no 40910 8350 38412 8381 3232 5629 992 32.6 26.8
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The underwater eruption in the Academia Nauk Caldera Jan.2-3, 1996
was a unique event, seen by specialists for the first time. As a result of
this natural event, the hydrological regime of the lake, along with its composition,
changed completely. This can be classified as a natural ecological catastrophe.
The results of the first year’s investigations into the consequences of the
eruption allow us to construct the long-term evolution process of the lake back
to its original state.
We would like to think Ya.D. Muravyev, V.I. Andreev, I.A. Markov for
taking regular samples, as well as monitoring the temperature and level in the
lake.
Our work was supported by the Russian Government Committee on Science and
Technology, the Russian Fund for Fundamental Research, and the INTAS fund
(project 94-3129).
Fedotov, S.A. The simultaneous eruption of two
volcanoes on Kamchatka in January 1996. «Zemlya
i vselennya». 1996. N3. P.60-65. (in Russian)
Karpov G.A., Muraviev Ya.D., Shuvalov R.A.,
Fazlullin S.M., Chebrov V.N. More details about
the early January eruption //Bulletin of Global
Volkanism Network. 1996. V 21. N 3. P. 9-10.
Karpov G.A., Muraviev Ya.D., Shuvalov R.A.,
Fazlullin S.M., Chebrov V.N. A subaqueous
eruption from the caldera of Akademii Nauk
volcano on January 2-3 1996 //Newsletter of the
IAVCEI Commission on Volcanic Lakes. 1996.
N9. P.14-17.