Sometimes I browse satellite images on WorldView to see what “my” volcanoes are up to. The other day I noticed a thermal anomaly on “Medvezhia”, Iturup Island, Kuriles. So I went back to look at every day of May and found that a red spot had shown on eight days in May, sometimes two spots, practically on most days the mountain wasn’t covered in thick clouds. Could that be a glowing hot lava dome, degassing, with an eruption to come, or a small one going on already? (As to hot gases: Momotombo has hot fumaroles over 900°C and on the webcams a great bright glow is visible every night. I have often checked on it, but thermal anomalies were only recorded at times of eruptions. Also Turrialba glows brightly but never shows a red spot.)
I checked at SVERT – all listed Southern Kurils’ volcanoes are at a Green alert level. Which is no surprise, because: “[Only] visual observations are used for the volcanoes of Kunashir and Iturup Islands. Surface instrumental observations are absent; there are no seismic networks on any of the volcanoes on the Kurile Islands.” A surprise was to me that neither Medvezhia as a complex nor its active cone Kudryaviy is listed as a monitored volcano at all, in spite of it having erupted in 1999. On a quick scan I found almost nothing about this volcano, so I embarked on a search mission. And by no means did I encounter an “obscure” volcano, rather one that had jumped into the lime light of money power and politics a few years ago… But let’s start on solid ground:
ITURUP (Russ.), or ETOFORU (Jap.) ISLAND
Note: Throughout my post I will stick to Russian names. Not to show a political standpoint but simply because a) Iturup is presently part of Russia, and b) most information I found on the volcano or on the island was written by Russians, very little from the Japanese side.
Iturup (Остров Итуруп) is one of Russia’s Southern Kuril islands which presently are disputed by Japan. With 200 km x 7-27 km it is the largest of the Kuriles and has 7500 or so residents. It also has one volcano for every 375 residents… I mean, there are 20, eight of them being active volcanoes. Medvezhia (Медвежий) is derived from Medvedj (медведь – bear), because bears are frequent visitors; traces of them are found even on the peaks of volcanoes. The Medvezhia (Moyorodake) volcanic complex occupies the NE end of Iturup Island. The rest of the island is beautiful volcanic landscape and ugly remains of Japanese military equipment.
At the Kurile-Kamchatka Trench, the Pacific Plate is subducting beneath the Okhotsk Plate, a microplate. The Kuril Islands consist of a double arc: The Lesser Kuril Ridge, an older inactive arc, begins at the Hokkaido E end and continues to the NE as the submarine Vityaz Ridge. And the younger, volcanic active Greater Kuril Ridge, extends for 1200 km from Hokkaido to the southern tip of Kamchatka.
The Greater Kuril Ridge is divided into three regions, northern, central, and southern on the basis of the submarine topography and the thickness of the crust. The Northern and the Southern Kuril Islands have the greater thickness of continental crust (15~30 km), whereas the thinnest oceanic crust (10~15 km, comparable to that of the oceans) is in the Central part.
The formation of the Kuril Archipelago began approximately 90 ma when the Okhotsk Terrane collided with the Siberian continent. A subduction zone formed along the SE margin of the Okhotsk Terrane. This initiated the formation of the Kuril-Kamchatka Trench and subsequent volcanism.
The Greater Kuril Ridge emerged during the early Pliocene. Some of the Kuril Islands have been above sea level since that time, while others have been formed by more recent volcanic activity. During the past 10 ma, the Greater Kuril Ridge has experienced intense volcanic activity and crustal uplift. Very large explosive eruptions (VEI 6) formed three calderas in the Kuril Islands, one on Onekotan Island, one on Ushishir Island, and Lvinaya-Past on Iturup Island (7,500 y.B.P).
There were at least two major sea-level regressions associated with glacio-eustatic changes in this region. Each time the sea receded by 100(-300) m below present sea level. The islands nearest to the northern and southern end of the Archipelago sit relatively shallow. Therefore, it is highly likely that these southernmost and northernmost islands were connected with each other and to nearby Hokkaido and Kamchatka, respectively, during the sea-level minima of the Late Pleistocene.
The Medvezhia volcanic complex is an E-W trending ridge within two overlapping Pleistocene calderas, 14 x 18 and 10 x 12 km in diameter. The caldera floor contains several lava domes, cinder cones and associated lava fields, and Slavnoe lake. In the eastern part four steep volcanic peaks rise side by side, beginning with the highest, Medvezhiy (1124 m), followed by Sredniy and Tukap/Kudryaviy (991m) volcanoes. Medvezhiy lies to the east, outside the caldera, along the Pacific coast. Sredniy has also produced lava flows that reached the coast.
Somewhat off to the west of the four is Menshoy Brat, a large thermally active lava dome with flank scoria cones.
Eruptions have been documented since the 18th century, all from Kudryavy: 1778/79, 1883 (lava flows), 1946(?), 1958 (minor explosion) and 1999 (phreatic eruption). The Japanese name Moyorodake refers mainly to Kudryavy volcano, although the GVP uses it for the entire complex.
KUDRYAVIY (вулкан Кудрявый, Moyorodake)
Kudryaviy is the part of the complex about everyone in Russia has heard of, probably many Japanese too, and which is the only part to have erupted in historical time. Kudryaviy is an active volcano of basaltic andesite (calc-alkaline) composition, with an elongate summit formed by three merged craters. It is younger than 2000 years, and magmatic eruptions here are of the Hawaiian type. Kudryaviy is almost merged together with Tukap, and both remain fumarolically active. The summit craters are mostly dry but after snow melting and strong rains shallow lakes may appear.
The eastern part is a flattened closed crater with a 20 m high andesitic hot lava dome in the center (that the one producing the thermal hot spot?). Just next to the dome the crater of a 1999 eruption has been blasted out. Numerous thick lava flows blanket the flanks of the cone and extend 2-3 km to the caldera walls. Those are from the last magmatic eruption in 1883 and originated from the third crater, in the western part of the summit. The report of a 1946 eruption was either erroneous or it was just a very weak phreatic explosion, because the ruins of Japanese mining works in the crater can still be seen today.
There are six fumarolic fields with temperatures in the range of 100-940°C and varying fumarole chemistry. Compositions of the Kudriaviy volcano fumarolic gases are typical of arc volcanism. However, the geometry and depth of the magmatic reservoir are still unknown even after seismic and gravimetric measurements. It was thought that the long-term high-temperature degassing at Kudriaviy is caused by a steady-state release of volatiles from the depth of arc magma generation and high heat flow from the mantle. Alternatively, convection and degassing in a stratified magma chamber has been suggested.
Interesting in this context is a description of changes of the surface around fumaroles on Kudryaviy: Volcanic gases, with a total emission rate of about 30000 tonnes per day cause alteration of lava and pyroclastic rocks, and form “fumarolic crusts” owing to rapid changes in the physico-chemical parameters of the venting gas. The thickness of these crusts varies from some centimeters to more than a meter. There are two layers of high- temperature crusts that formed on the basaltic andesites: the upper layer (up to 20 cm) consists of secondary sulfates and oxides with relics of minerals from the original rocks, and the lower layer is dark in color owing to the presence of sulfides. Ore sublimate mineralization forms in gas-release cracks. Most sulfides occur at depths of 10–50 cm.
THE 1999 ERUPTION from KUDRYAVIY
Kudriaviy has been consistently degassing passively at high temperatures since at least 1961, when it was first visited by Russian scientists. These low-pressure fumaroles, some with temperatures up to 950°C, produced hissing to roaring – to deafening – levels of noise. There was more noise and higher flux than at Momotombo, where 950°C-fumaroles were studied through the early to mid-1980s by U.S. and Russian collaboration. At their annual visits during summer field work, the scientists had noted very little change in the behavior of the volcano.
Then, in mid-September 1999, temperature measurements of sediments in the dry crater lakes showed increases by 60-102 degrees.
In spite of the unusually dry weather the water in Hot Lake still covered more than half the area. The lake water close to the hot dome was boiling and seething due to gas emissions. Fumarole gas compositions during the second part of September showed increased hydrogen, oxygen, and fluorine contents. Sulfur ignition was seen in some locations. The number of earthquakes also increased, and although the one-channel seismic station deployed was insufficient to determine any hypocenters, the elevated seismicity was obvious. No doubt – an eruption was imminent! Local authorities were warned that Kudriaviy was unstable and could erupt soon – which it did, three days later, on 7 October 1999.
The eruption created a new crater, 30 x 40 m wide and with over 30 m deep steep walls in the Hot Lake area, and it removed part of the dome. In the lower part of the crater wall was a 6 x 8 m cavity of incandescent rocks. Based on the light intensity, the temperature was estimated to be higher than 1,000-1,100°C. Hot gas rose from this area. Small fiery patches and fragments with burning sulfur were seen on the S, W, and N walls.
No juvenile ash was identified, so the eruption was determined to be phreatic. This eruption was similar to a geyser eruption: periodic vertical ejection of gas, ash and steam. Minor explosions continued from the cave until 13 October. Activity then declined, consisting of gas emissions with some small rock fragments that didn’t reach the crater rim. Observations ended on 2 November.
FOUND SOMETHING… WHAT’S THIS?
So, why in the name of the marmot did the Russians start extensive research on one of the remotest, rarely erupting, island volcanoes of their country? Of course there was a reason, seemingly more important than “just” getting to know the behaviour of a volcano to protect the small local population:
One day in 1992 Russian scientists G. Steinberg and colleagues were doing field work near the fumaroles with their shovels and thermometers. When they looked at a piece of rock with some blackish crystals it seemed at first to be the common mineral molybdenite, but hmm… it appeared to be ever so slightly different… The rock was sent to the laboratory, and HEY! They had discovered, for the first time, a very rare mineral at the Kudryaviy crater: Rhenium disulfide (ReS2). Also called Rheniite, it precipitates in the high-temperature fumaroles as an unusual subsurface sublimate. There it crystallizes in the form of needles and plates directly from volcanic gas. It is the only known mineral with rhenium as its primary metallic constituent (i.e. as the only cation). So far, Re was believed to only exist in trace amounts on the Earth’s surface, but this was the first example of macroscopic rhenium mineralization. The condensation of pure rhenium disulphide from this fumarole gas requires both enrichment of rhenium by eight orders of magnitude as well as remarkable selectivity. These findings demonstrated that Re can be readily mobilized, dispersed and concentrated by degassing magmas.
Rhenium is also a strategically valuable metal that is used mainly in the military industry; high-strength superalloys for space and aviation equipment with 4 to 10% rhenium can withstand temperatures of 2000°C and more without loss of strength. In 2014, the world’s rhenium production was about 44 t, the price being some $ 3000 per kg, or higher, depending on purity.
In 2003, Russian scientists successfully carried out experimental work on the extraction of rhenium from the disulfide emitted by the fumaroles. The intention was then to build a concrete dome over one of the fumarolic fields and directly catch the hot gas, lead it through a bed of natural zeolites (porous, high surface area) where it would condense, depositing the precious mineral. This way, Kudryaviy volcano could produce 20 t of rhenium annually. Half of that would cover all Russia’s needs for the rare metal and leave the rest for export… do the calculations!
That sounded like a very futuristic idea, to say the least. To be sure, the volcano will not deliver the goodies easily, one “minor” obstacle (of the many) being the risk of eruption. But, wouldn’t you know, they are working on it… a plan is made, spanning to 2020, some funds are allocated, investors were found. In 2015 scientists managed to extract the first 17 kg of rhenium from the crater in a pilot project. The latest news (4/2017) is that preparatory work is underway to create an infrastructure for the installation and operation of the plant. A prefab spherical dome was already delivered last year, but it could not be mounted before winter – new plan is for this year. Just imagine that – building a road and transporting a factory up the rugged slopes of that fuming mountain, labouring under gas masks, hampered by rough weather and frightened by a roaring volcano…
This seems to be not only a matter of economy but also – a matter of perseverance and principle. And of politics of course… no longer can anyone call the Kuril islands “some useless empty pieces of land that Russia probably doesn’t really have any use for”…
The above description of the 1999 eruption was given at the time by the head geologist G.S. Steinberg (Biography, transl.), and a translation appeared as GVP Bulletin. Originally, he concluded with an important thought:
“Unfortunately, the use of the seismic part of the automated telemetry system of the operational eruption forecast, first deployed on Iturup in 1995, has been frozen for three years, since the [authorities] do not have the resources necessary to ensure its operation.
There are decisions, programs, contracts, resolutions, on federal and regional levels, but there is no money; and according to the Russian tradition, it probably never will be… until the “eruption with consequences” happens… The cost of work to ensure the safety of the population of the southern Kuriles in terms of Per Capita is about 8 rubles – per month – slightly more expensive than the cost of a ticket in a city bus. Maybe we’ll ‘overcome ourselves’ without waiting for ‘thunder to break out’, and find these funds. Or is ‘the Kuril’s soul’ not worth the money?” (Transl. Google)
I guess, with the Rheniite being so precious, there are at this very moment workers up there in the sulfurous hell. I further guess (see SVERT statement at the top of this post) they’ll get no warning whatsoever concerning upcoming eruptions… and I hope I am wrong. Are there reasons why Kudryaviy is not even listed as a volcano? With the Red Dots on Kudryaviy in the satellite images, I am getting a bit worried for them. There’s been another one today.
Disclaimer: I am not a scientist, all information in this (and any of my other posts) is gleaned from the www and/or from books I have read, so hopefully from people who do get things right! 🙂 If you find something not quite right, or if you can add some more interesting stuff, please leave a comment.
Enjoy! – GRANYIA
SOURCES & FURTHER READING
– GVP, Moyorodake
– Hydrogen isotope geochemistry and heat balance of a fumarolic system: Kudriaviy volcano (paywalled)
– Active Volcanoes in Japan, Moyorodake (1974, PDF)
– Minerals of the System ZnS-CdS from Fumaroles of the Kudriaviy Volcano (paywalled)
– Geology of the Kuril Islands
– Factory on a Volcano (article, 2000)
– Article in “Regnum” (2014, News))
– Discovery of a pure rhenium mineral at Kudriaviy volcano (1994)
– Remarkable Biography: G.S. Steinberg (in Russian)
– Video: G.S. Steinberg on rheniite from Kudryaviy (Russian)
– Extraction of rhenium […] will begin in 2019 (2917, News)