However, back to active volcanoes. In the Soviet Union, the edge of active volcanoes lies in the east, at the very borders of our country. This region illuminated by the lights of eruptions is Kamchatka and the Kuril Islands. There are 129 volcanoes in Kamchatka. They form an almost continuous volcanic belt stretching along east coast peninsula.
29 volcanoes are active or have fallen asleep for a while, the rest are considered extinct.
In the north of the Kamchatka volcanic belt, the Sheveluch volcano rises. To the south of Sheveluch, in the right bank of the Kamchatka River basin, there is the famous Klyuchevskaya group of volcanoes. It also contains the highest volcano in Eurasia - Klyuchevskaya Sopka. Further to the south, a strip of active and extinct volcanoes stretches for several hundred kilometers. In the vicinity of the city of Petropavlovsk, this strip is enclosed by the Avachinskaya Sopka. Finally, in the very south of the peninsula, in the family of dormant and extinct volcanoes, there is another interesting volcano - Ksudach, which has been dormant for more than 50 years. In the past, it seems to have been one of the largest volcanoes in the south of Kamchatka.
In 1935, the Volcanological Station of the USSR Academy of Sciences was built at the foot of Klyuchevskaya Sopka in the village of Klyuchi. Since that time, for more than a quarter of a century, volcanologists have been continuously monitoring Kamchatka volcanoes. Researchers have collected a wealth of material about the nature of eruptions, about changes in the activity of volcanoes, about the temperature and composition of their lavas.
It turned out that the volcanoes of Kamchatka are very diverse. Almost everyone has their own characteristics, shchzh "temper". Sheveluch, by the nature of its eruptions, is a fellow of the Mont Pele volcano in Martinique and the Indonesian Merapi. The closest "relatives" of the Klyuchevskoy volcano, similar to it in behavior, are in Italy. These are Etna and the volcanoes of the vicinity of Naples.
The lavas of Sheveluch, the northernmost of the Kamchatka volcanoes, are very viscous and contain a huge amount of vapors and gases. During eruptions, they do not form streams flowing down the slope of the volcano, but are slowly squeezed out of the crater and piled over it in the form of a dome. During the 1945 eruption, the squeezing of lava was accompanied by the strongest explosions that shook the neighborhood for tens of kilometers around. During the explosions, clouds of hot gases burst out from under the lava dome. These clouds contained an enormous amount of small lava particles. With tremendous speed, they rolled down the slopes of the volcano and burned everything in their path. The eruptions of Sheveluch make themselves felt at a great distance. On a fine September day in 1964, we were at the foot of the Klyuchevskoy volcano. The path passed through flat terrain, in some places cut by the valleys of "dry" rivers. Here and there there were glacial boulders, or even huge blocks, covered with black-gray volcanic ash, born of the eruptions of the Klyuchevskoy volcano. It was a kind of ash-stone desert. Ashes easily rose into the air and clouds of volcanic dust remained behind the traveler. But in the cliff of the Apakhonchich stream valley, among the ash, sand and gravel deposited by the water, something else could be seen. Against the background of this dark gray mass, two layers of yellowish-gray volcanic ash were clearly distinguished (Fig. 23), completely different from the ash of Klyuchevskoy volcano. This is Sheveluch's ashes. The upper layer arose during an eruption in the middle of the last century. The distance the ash was transported from the volcano to the place of its burial in a straight line is about 60-70 km.
Volcanoes of the Klyuchevskaya group behave differently during eruptions. This group consists of twelve volcanic cones. All of them are located on a single lava pedestal, apparently representing the remains of a huge, more ancient volcano. The largest and most active volcano in this group is Klyuchevskoy. It is rightfully considered a handsome volcano. Its tall, regular cone is crowned with a white top that is constantly smoking or illuminated by reflections of fire (Fig. 24). Like a gigantic lighthouse encased in ice, it is visible from the sea at a distance of several hundred kilometers.
At the top of Klyuchevskoy volcano there is a huge bowl-shaped depression - a crater with a diameter of about 0.5 km. In the depths of the crater, deep channels darken, going into the bowels of the volcano. Puffs of dark and white vapors, clouds of ash and red-hot stones rush out of these channels every minute with a roar. When the volcano is calm, ash and stones fly up only to a height of 200-300 m and fall back into the crater.
Employees of the Volcanological Station descended into the crater of Klyuchevskoy Volcano and found that the entire bottom of the crater was covered with loose volcanic ash. Plunging into it knee-deep, volcanologists tried to get to the central channel - the vent. But they did not succeed. Explosions followed one after another, hot stones continuously flew from the vent. I had to stop a few tens of meters from the border of the falling stones. Then the explosions intensified, the "jets" of red-hot stones quickly hit from the depths of the volcano, and the entire bowl of the crater began to quickly become covered with clouds of dark smoke. The researchers had to retreat.
It was possible to climb to the top of Klyuchevskaya volcano and descend into the crater during a period when the volcano was relatively calm. And Klyuchevskaya Sopka is famous for the strength and duration of its eruptions. One of the last major eruptions lasted from the end of 1944 until the summer of 1945. When it began, the walls of houses at a distance of 50 km from the volcano trembled from the roar of explosions. Volcanic ash fell all over the peninsula. Towards the end of the eruption, several large explosion craters formed along the crack stretching from the top of the hill to its foot, and a small slag body grew at the lower end of the crack. The outpouring of lava began from it.
Volcanoes like Klyuchevskoy, composed of lava flows and layers of volcanic ash and bombs, are called layered, or stratovolcanoes. Eruptions gradually increase the height of Klyuchevskaya Sopka. They repeat on average after six to eight years, and each eruption increases the volume of the volcanic cone by about 0.5 km 3. Having determined the volume of the cone of Klyuchevskoy volcano, scientists calculated that it was formed in seven hundred eruptions. Thus, it was established that Klyuchevskaya Sopka is a relatively young volcano. Its formation began about 5000 years ago.
In the center of the Klyuchevskaya group is the Bezymyanny volcano, which for a long time was considered extinct. However, in October 1955, he suddenly woke up. The awakening was unusual and terrifying. It started with earthquakes in the vicinity of the volcano. Explosions followed, and the volcano began throwing out ash. The amount of ejected ash gradually increased, it was carried over a distance of 100 km. In places the ash fell so thickly that the sun's rays did not penetrate through its veil. During the day it was getting dark as at night.
Then the eruption began to subside, but suddenly on March 30, 1956, there was an explosion of monstrous force. A cloud of ash soared to a height of 40 km above the volcano. A jet of hot gases burst out of the crater, which burned and knocked down trees even at a distance of 25 km from Bezymyanny. The top of the mountain and the entire eastern part of the cone were blown up. A hot mass of loose material, consisting of volcanic ash and boulders of various shapes and sizes, poured into the resulting gap from the revived volcano. The ejection of a loose stream of incandescent debris was so rapid that it quickly filled the river valley to a depth of 80-100 m. The stream cooled down for several months, and thousands of jets of hot vapors and gases rose from its surface.
As a result of the explosion of Bezymyanny, volcanic ash was blown away at a distance of 400 km in a radius, and the volcano itself dropped by almost a third of a kilometer. At its top, a giant crater appeared in the form of a half-ring, open to the east. Such large depressions, formed during volcanic explosions, are called calderas. After the explosion, viscous lava began to gradually squeeze out from the bottom of the caldera of Bezymyanny volcano after the explosion, which by the end of the eruption formed a dome about 300 m high.
The eruption of Bezymyanny lasted for almost a year and ended only in the fall of 1956. It was calculated that the explosion on March 30, 1956 released a colossal amount of energy, equal to about 4 10 23 erg. This amount of energy is generated by the Kuibyshevskaya HPP throughout the year. Force air wave was monstrously huge, and its initial speed was almost twice the speed of sound. Apparently, the eruption of Bezymyanny was one of the strongest volcanic explosions ever observed by humans.
In subsequent years, the activity of Bezymyanny manifested itself only in summer time, mainly in the growth of the dome and the formation of stone obelisks on it. In the early autumn of 1964, we were able to see for ourselves the intensification of the volcano's activity. On the southeastern slope of the crater, two pointed gray obelisks were squeezed out. A fiery glow could be seen over the obelisks at night. On the slope, landslide and hot pyroclastic avalanches rolled down, which, like a cutter, cut through a deep and narrow hollow-gap on the slope of the volcano. In some places, lava was showing through the cracks. Judging by the color, its temperature was about 900 ° C. On September 9, 1964, Bezymyanny's activity began to decrease, but in the following September days, dark smoky clouds up to 3-4 km high rose above the volcano.
Avachinsky volcano, like Klyuchevskoy, is also layered. Its eruptions are very similar in nature to the eruptions of Mount Vesuvius, located in the vicinity of Naples. The last major eruption of Avacha volcano took place in the winter of 1945. It lasted less than a day. After several violent explosions, a mushroom-shaped black ash cloud several kilometers high rose above the cone of the volcano. It swirled, lit up with crimson reflections, volcanic bombs flew out of it, ash fell. Bombs and hot ash melted snow at the top of the volcano, and rushing streams of hot water and mud rushed from the slopes of the mountain. Then the ash cloud began to dissipate, and the volcano calmed down.
Ksudach, located in the south of Kamchatka, is a volcano-caldera. Once it was a large volcano with a diameter of about 20 km, but during one of the eruptions its cone was destroyed by a strong explosion. A funnel-shaped caldera basin with a diameter of 8 km was formed, surrounded on all sides by a low ring-shaped ridge. There is now a lake inside the ring, along the banks of which pairs of numerous fumaroles rise.
The last eruption of the Ksudach volcano took place in 1907. It began with a strong explosion and the release of a huge amount of ash. Fine volcanic dust rose into the stratosphere and was carried away tens of thousands of kilometers from the volcano. As a result of the explosion, a new funnel appeared inside the caldera itself, with a diameter of about 1.5 km, with almost vertical walls. Soon a lake formed in this smaller, inner caldera.
In addition to volcanoes, there are many geysers in Kamchatka - boiling springs that periodically throw out fountains of hot water. In the valley of the Geysernaya River there are about twenty large and at least a hundred small geysers. The water temperature in them reaches 94-98 ° С. The largest geyser - "Giant" - throws out giant jets of water to a height of 40-50 m every 3-4 hours.
The abundance of vapors released during volcanic eruptions, a huge number of geysers and hot springs indicate that huge reserves of superheated steam and hot water are hidden in the depths of the Kamchatka Peninsula, which can easily be used for human needs. In the land of volcanoes in Iceland and in the vicinity of Naples in Italy, people are already using the volcanic heat of the bowels. Hot steam from hundreds of boreholes turns power plant turbines, heats homes, and drives machine tools in factories. And we have started drilling test wells in Kamchatka to get hot water and steam. They will be used for heating and technical purposes in fish canning factories.
The continuation of the belt of Kamchatka volcanoes are volcanoes Kuril Islands... The Kuril arc stretches for 1200 km between the southern tip of Kamchatka and the Japanese island of Hokkaido. The underwater ridge, the peaks of which are the islands of the Kuril arc, serves as the border separating the Sea of Okhotsk from the endless expanses of the Pacific Ocean. There are 61 extinct and 39 active volcanoes on the islands of the Kuril arc. The most active of them are Alaid, Ebeko, volcanoes Krenitsin, Mendeleev, etc.
The largest of Kuril volcanoes- Alaid. Its summit, crowned with a small glacier, rises to 2300 m above sea level. People have repeatedly observed the eruptions of this volcano. The last eruption of Alaid was in 1932. It did not occur through the main crater, but through a crack in the underwater part of the volcano. As a result of this eruption, a smoking island appeared in the sea, which turned out to be a side cone of Alaid. The cone had its own crater. A few years after the end of the eruption, the island was connected by sand bars with the parent island and turned into the Alaid Peninsula.
In the fall of 1952, after a long sleep, the Krenitsina volcano, located on the Onekotan Island, one of the northern Kuril Islands, awakened. The volcano is located in the southern part of the island in an ancient caldera. The cone of Krenitsin volcano rises from the blue waters of the lake, which fills the wide funnel-shaped bowl of the caldera. The eruption began with a roar, which was heard at a distance of 100 km from the volcano. Out of the waters blue lake clouds of vapor rose, then a cloud of ash rose over the island and covered the volcano with an impenetrable curtain. Ashes fell throughout the day, thickly covering the island. At night, a fiery glow appeared over the crater. Ash clouds, illuminated by the reflections of the eruption and bright flashes of lightning, were carried by the wind into the ocean. From a distance, from the passing steamers, it seemed as if a fiery whirlwind burst from the depths of the ocean. After a few days, the eruption gradually began to weaken, and a week after awakening, the volcano again calmed down and has been sleeping for more than ten years.
The volcanoes of Kamchatka and the Kuril Islands are associated with huge faults in the earth's crust. An entire belt of such faults borders the Pacific Ocean. Molten masses of sub-crustal matter - magma - rise from the depths of the Earth along the cracks of the faults. In places of their emergence volcanoes, Sheveluch, Klyuchevskaya Sopka, Bezymyanny, Ksudach, Alaid, Krenitsina volcano and the remaining 233 extinct, dormant and active volcanoes of the Kuril-Kamchatka arc appear, represent only a small part of the Great Fiery Pacific Ring, numbering hundreds of submarine and surface volcanoes. The amazing cluster of volcanoes around the Pacific Ocean and at its bottom is one of the many mysteries of geology. To solve this mystery, geologists of future generations will have to penetrate to the bottom of the greatest ocean on Earth. And when the ocean floor is studied at least with the same detail with which geologists have now studied the earth's continents, the mystery of the Pacific Ring of Fire, which contains more than two-thirds of the Earth's volcanoes, will probably be close to resolution.
Volcanoes of the Kuril Islands
Volcanic activity is observed exclusively in the Great Kuril Ridge, the islands of which are mainly of volcanic origin, and only the northernmost and southernmost ones are composed of sedimentary rocks of the Neogene age. These rocks serve here as the foundation on which volcanic structures arose.
The volcanoes of the Kuril Islands are confined to deep faults in the earth's crust, which are a continuation of the faults of Kamchatka. Together with the latter, they form one volcanic and tectonic Kuril-Kamchatka arc, convex towards the Pacific Ocean. There are 25 active volcanoes on the Kuril Islands (4 of them are underwater), 13 are dying and more than 60 are extinct. The volcanoes of the Kuril Islands have been studied very little. Of these, the Alaid volcanoes, Sarychev peak Fuss, Snow and Milia are distinguished by their increased activity. Alaid volcano is located on the first northern island (Atlasov Island) and is the most active of all the Kuril volcanoes. It is the highest (2239 m) and rises beautifully in the form of a regular cone directly from the sea surface. At the top of the cone in a small depression is the central crater of the volcano. By the nature of the eruptions, the Alaid volcano belongs to the ethno-Vesuvian species. For the last 180 years, eight eruptions of this volcano and two eruptions of willows of the Taketomi side cone, formed during the period, have been known. eruption of Alaid in 1934. Volcanic activity on the Kuril Islands is accompanied by numerous hot springs with temperatures ranging from 36 to 100 C. The sources are diverse in form of manifestation and salt composition and are even less studied than volcanoes.
Underwater volcanic group "Paramushirskaya"
Within this volcanic group, the underwater volcano Grigoriev, an underwater volcano located to the west of about. Paramushir and underwater lava cones at about. Paramushir.
Grigoriev's underwater volcano. The flat-topped submarine volcano Grigoriev, named after an outstanding Russian geologist, is located 5.5 km north-west of the island. Atlasov (Alaid volcano) (Fig. 17).
It rises from a depth of 800-850 m, and its base has grown together with the base of the Alaid volcano. Grigoriev volcano is located on the general line of the north-north-western direction of the location of the side cones of the Alaid volcano.
The dimensions of the base of the volcano along the 500 m isobath are 11.5 8.5 km, and the volume of the edifice is about 40 km 3. The steepness of the slopes reaches 10o-15o.
The summit of the underwater volcano Grigoriev was cut off by abrasion and leveled to a level of 120-140 m (Fig. 18), which practically corresponds to the sea level in the Late Pleistocene. In the southern part of the summit, there are rocky ledges rising to a depth of 55 m. Apparently, these rocky ledges represent a prepared neck.
Continuous seismic profiling records indicate that the volcanic edifice is composed primarily of dense volcanic rocks.
An intense magnetic field anomaly with a magnitude of more than 1000 nT is confined to the underwater volcano Grigoriev (see Fig. 18). All rocky outcrops, marked in the southern part of the flat top, are clearly recorded in the magnetic field by the presence of local anomalies. The volcanic edifice is magnetized in the direction of the current magnetic field.
During the dredging of the underwater volcano, basalts were raised, varying in composition from very low-siliceous to high-siliceous varieties. The remanent magnetization of these basalts varies in the range 7.3-28.5 A / m, and the Koenigsberger ratio - in the range 8.4-26.5.
The data of echo sounding, continuous seismic profiling, hydromagnetic survey and measurements of the magnetic properties of dredged samples suggest that the entire edifice of the Grigoriev submarine volcano is composed of dense basalts.
The presence of a pre-Holocene 120-140 m terrace and the magnetization of the volcanic edifice in the direction of the modern magnetic field makes it possible to estimate the age of the volcano's formation in the range of 700-10 thousand years ago.
Underwater volcano to the west of the island. Paramushir. In 1989, on the 34th and 35th cruises of the R / V Vulkanolog in the rear part of the Kuril arc, 80 km west of the island. Paramushir was discovered and studied in detail a previously unknown underwater volcano.
This underwater volcano is located at the intersection of the Atlasov Trough with the continuation of the transverse structure of the 4th Kuril Trough. Like the underwater volcanoes Belyankin and Edelstein, it is located far in the rear of the Kuril island arc and is 280 km away from the axis of the Kuril-Kamchatka trench.
The volcano is located on a gentle slope of the trough, towering 650-700 m above the surrounding bottom of the Sea of Okhotsk (Fig. 19). Its base is slightly elongated in the northwest direction and measures ~ 6.5 7 km. The top of the mountain is complicated by a number of peaks. The negative form of the relief encircles the base of the volcano in an almost closed ring.
In the vicinity of the volcano, there are no extended scattering horizons in the sedimentary section. Only at the very base is sometimes a non-extended “acoustically turbid” wedge, caused, apparently, by the accumulation of detrital material and slumped sediments. The position in the section of this "acoustically turbid" wedge corresponds to the estimated time of the volcano's formation, which, according to the NSP data, is 400-700 thousand years.
The structural features of the sedimentary cover indicate that the breakthrough of magma to the bottom surface here was not accompanied by a large-scale accumulation of volcanic-sedimentary material, and, most likely, ended with the formation of one or a series of volcanic extrusions. Most likely, the entire structure is composed of volcanic rocks.
At a distance of 5-10 km from the volcano, according to the NSP data, three small (apparently magmatic) bodies were identified that did not reach the bottom surface. The overlying sediments are crumpled into anticlinal folds.
The anomalous field (T) a in the area of the underwater volcano is characterized by positive values. Only in the northwestern part of the study area are negative field values with an intensity of up to -200 nT. The areas of positive and negative values of the magnetic field are separated by a linear zone of high gradients with a northwest strike. The horizontal field gradient in this zone reaches 80-100 nT / km. A positive magnetic field anomaly with an intensity of up to 400-500 nT is confined directly to the volcanic edifice. Near the summit part of the edifice, a local maximum with an intensity of up to 700 nT was noted. The maximum of the anomaly is displaced south of the summit of the volcano. The noted magmatic bodies that have not reached the bottom surface are not expressed as independent anomalies in the anomalous magnetic field.
The observed pattern of the anomalous magnetic field indicates the direct magnetization of the underwater volcanic edifice.
Most likely, the age of the volcano formation is no older than 700 thousand years, which is in good agreement with the NSP data.
When dredging the summit of the mountain, mainly amphibole andesites were raised, with a subordinate amount of pyroxene andesite-basalts and plagiobasalts. Fragments of granitoids, andesitic pumice, slags, pebbles of sedimentary rocks, iron-manganese formations and bottom biota are present in small quantities.
The data of echo sounding, NSP, HMS and geological sampling suggest that the bulk of the volcanic edifice is composed of rocks of andesite-basaltic composition.
Underwater lava cones at about. Paramushir. On a number of cruises of the R / V Vulkanolog and on cruise 11-A of the R / V Akademik Mstislav Keldysh, a study of underwater gas-hydrothermal activity on the northwestern slope of the island was carried out. Paramushir. On cruise 11-A of the R / V Akademik Mstislav Keldysh, either 11 dives of the Paysis VII and Paysis XI manned underwater vehicles (PAS) were carried out in the study area, or 13.
The signal for such a close study of this area was a radiogram sent on March 20, 1982 by the captain of the fishing vessel "Pogranichnik Zmeev" to the newspaper "Kamchatskaya Pravda" that near about. Paramushir "an active underwater volcano was discovered at a depth of 820 m, an extreme height of the outburst of 290 m ...". In April of the same year, during the 13th cruise of the R / V "Vulkanolog" at the indicated point, acoustic interference was detected, clearly manifested in the echo sounder records. Similar records were repeatedly recorded during research on board research vessels in the area of active volcanoes and were associated with the action of underwater fumaroles. In its shape, the detected interference resembled a torch. Subsequently, when conducting research at this point, acoustic interference on the records of various echo sounders installed on board the R / V "Vulkanolog" was noted up to 1991, when the last specialized voyage No. 40 of this vessel was carried out within the RCD.
Before the start of the research in the area of the "torch" there were no signs of manifestation volcanic activity... To establish the nature of the "torch" of anomalous water, so many studies were carried out. They made it possible to establish that the "torch" was formed by underwater gas hydrothermal vents (GHTV), similar to underwater fumaroles, but not directly associated with any volcanic center. Therefore, it would be wrong to apply the term "underwater fumarole" to it.
PGTV is located on the west-northwestern slope of about. Paramushir is in the rear of the KKOS, approximately in the middle between the Alaid and Antsiferova volcanoes. Its coordinates are 50o30.8 "N and 155o18.45" E. It is confined to a weakly manifested transverse volcanic zone, represented by almost completely buried extrusive domes or small volcanic cones extending from the Chikurachki volcano in the west-northwest direction. On the NSP records, these structures are similar to the side cinder cones of the Alaid volcano, which also have a transverse orientation with respect to the KOD. Most of the buried structures are 0.5-3 km in size at the base and 50-400 m in height. Taking into account that these dimensions are less than the inter-gall distance, excluding a small area around the PGTV itself, it can be assumed that the number of buried structures in the described area is somewhat larger. It should be noted that the buried structures in the KOD area during volcanological expeditions from the R / V Vulkanolog were found only in two places: in the PGTV area and near an underwater volcano to the west of the island. Paramushir.
According to the HMS data, not all volcanic buried structures have the same structure. Some of them are not expressed in any way in the magnetic field, but are only recorded on the NSP tapes, distinct positive or negative magnetic field anomalies are associated with others, and they are, most likely, lava domes or cones, frozen mainly in the thickness of the sediments. Non-magnetic cone-shaped structures can be composed of cinder cones or felsic rocks.
The largest lava cone is located at the northeastern end of the detailed study area. It is almost entirely located within the sedimentary stratum, here with a thickness of more than 1500 m.Only its summit part rises above the bottom surface, forming a hill 100-120 m high.The fixed depth above the summit is 580 m. The dimensions of this structure in its lower part at a depth of 800 -1000 m from the bottom surface reach 5-6 km. The size of the building along the buried base is 7.5 11 km, the area is ~ 65 km 2, the total height is 1600 m. The steepness of the slopes of the building is 5o-8o. A smaller cone with a base size of ~ 3 km adjoins it from the south-southwest. Both of these structures are magnetic and form an anomaly, within which two extrema with intensities of 370 and 440 nT are noted (Fig. 4). The buildings are magnetized in the direction of the modern magnetic field, and the age of their formation is not older than 700 thousand years.
The performed two-dimensional modeling showed that the effective magnetization of the northern cone is 1.56 A / m, and that of the southern one is 3.7 A / m. Based on the average values of the effective magnetization for submarine volcanoes, it can be assumed that the northern cone is composed of andesites, and the southern one - andesite-basalts.
Plagioclase-hornblende andesites and prevailing homogeneous basalts were sampled during the PLA dives on the northern cone.
Comparison of the results of geomagnetic modeling with the data of geological sampling suggests that the upper part of this cone is composed of basalts, and the deeper parts are composed of andesites.
Estimates of the age of the northern cone, given in various works, vary within the Neogene-Quaternary.
A small cone located in the southern part of the detailed work area has a base size of ~ 1.5 km in diameter. It is associated with a negative magnetic field anomaly with an intensity of -200 nT (see Fig. 4). The effective magnetization of this cone is 1.3 A / m, which corresponds to the magnetization of andesite volcanoes. The negative character of the magnetic field suggests that the age of the formation of this cone is not less than 700 thousand years.
It should be noted that the PGTV is located in a zone of increased fracturing with a large number of small faults.
The submersions of the PAD in the zone of the HWP showed that the most characteristic relief forms in the zone of the HWP are chaotically located sinkholes and pits. The size of the pits varies from 1 to 10 m in diameter and is up to 3 m deep. The distance between the pits is 0.5-2 m.
PGTV is associated with the deposits of solid gas hydrates.
The staff of the Institute of Oceanology of the Russian Academy of Sciences believe that the investigated outlets are gaseous and not hydrothermal.
The studies carried out have shown that the PGTV are located within the weakly expressed volcanic zone of the Quaternary (Neogene-Quaternary?) Age. They are confined to the zone of increased fracturing and are not directly associated with any volcanic center. The nearest non-magnetic (slag?) Cone is located ~ 2 km east-southeast of the point of acoustic interference.
Underwater volcanic group "Makanrushi".
Within this volcanic group, contrasting underwater volcanoes Belyankin and Smirnov, named after prominent Russian geologists, were studied. These underwater volcanoes are located in the rear of Onekotan Island (see Fig. 17). The underwater volcano Belyankin is located 23 km north-west of the island. Macanrushi (fig. 21). On the navigational charts, prior to the work from the R / V Vulcanolog, two distinctive depths were shown in this area, which could be the depths marked above the peaks of this underwater volcano. Our studies have unequivocally shown that the underwater volcano Belyankin has only one peak.
Volcano Belyankina has the shape of an isometric cone and rises above the surrounding bottom to an altitude of about 1100 m. The sharp summit of the volcano is located at a depth of 508 m. Belyankina volcano is located not only outside the mountain structure of the Kuril-Kamchatka island arc, but even on the other side of the Kuril Basin - on its northwestern slope. The maximum size of the base of a volcanic edifice is 9 7 km with an area of about 50 km 2. The volcano has steep slopes. Their steepness increases in the direction from the base to the top from 15o-20o to 25o-30o. The slopes of the volcano rising above the bottom of the basin are devoid of a sedimentary cover. The base of the volcano is overlapped by a thick layer of sediments. On the seismograms of the NSP, they correspond to the picture of the seismoacoustic image, which is generally typical for the sedimentary strata of the given region of the Sea of Okhotsk. The volume of the volcanic edifice, taking into account the part covered by sediments, is ~ 35 km 3. The thickness of sedimentary deposits near the volcano exceeds 1000 m. With the available estimates of the rate of sedimentation in the Sea of Okhotsk (20-200 m / million years), the formation of this stratum would take from 1 to 10 million years.
The underwater volcano Belyankina is clearly manifested in the magnetic field. It is associated with a magnetic field anomaly with a range of 650 nT, the extremum of which is shifted to the southeast of the summit (see Fig. 21). The volcanic edifice has direct magnetization.
Dredging of the underwater volcano Belyankin raised homogeneous olivine basalts. Based on the study of dredged rocks, some authors believe that the volcanic eruptions occurred in underwater conditions, while others - that in overland conditions.
Measurement of the magnetic properties of the dredged samples showed that their remanent magnetization varies within 10-29 A / m, and the Koenigsberger ratio - within 5.5-16.
To interpret the HMS data, a 2.5-dimensional modeling was carried out according to the methodology proposed in the work. As a priori information, we used the materials of echo sounding measurements and NSP. One of the most realistic models, in which the best coincidence of the curves of the anomalous and model magnetic fields is observed, is shown in Fig. 6.
It follows from the simulation results that the anomalous magnetic field in the volcano area is mainly due to its construction. The role of the deep roots of the volcano is very insignificant. The rocks composing the volcanic edifice have direct magnetization and are rather homogeneous in composition, which is in good agreement with the data of geological sampling. Simulations carried out with two other independent techniques gave similar results.
Comparing the modeling results with the NSP and echo sounding data, and taking into account the freshness of the dredged material, it can be assumed that, most likely, the sedimentary stratum was breached during the formation of the volcanic edifice. The base of the volcano apparently began to form in the Pliocene, and the bulk of the edifice was formed in the Pleistocene.
The underwater volcano Smirnov is located 12 km north-north-west of the island. Macanrushi (see fig. 21). Its base at a depth of about 1800 m merges with the base of Makanrushi Island. Slopes about. Macanrushi are covered with a thick (up to 0.5 s) cover of "acoustically opaque", probably volcanic and volcanic-sedimentary, sediments. The same deposits overlap the southern part of the base of the Smirnov volcano and, as it were, "flow around" it from the southwest and southeast. From the north, the foot of the volcano is covered by sedimentary deposits with a thickness of at least 1000 m, usual for this region of the Sea of Okhotsk. According to the available estimates of the rate of sedimentation in the Sea of Okhotsk, the formation of this stratum would take at least 5 million years.
The flat summit of the volcano is located at a depth of 950 m and is overlain by horizontally layered sediments with a thickness of 100-150 m. The maximum size of the base of the volcano is 8-11 km, with an area of ~ 70 km 2, and the flat top is 2? 3 km. The relative height of the volcanic edifice is 850 m, and the volume is about 20 km 3.
The underwater volcano Smirnov is also clearly manifested in the magnetic field, and an anomaly of the magnetic field with an amplitude of 470 nT is confined to it (see Fig. 21). The volcanic edifice has direct magnetization.
During the dredging of Smirnov volcano, a variety of rocks were raised, varying in composition from basalts to dacites.
Dredged andesite-basalts have a remanence of 1.5-4.1 A / m and a Koenigsberger ratio of 1.5-6.9, and andesites have 3.1-5.6 A / m and 28-33, respectively.
To interpret the HMS data, 2.5-dimensional modeling was performed using the methodology proposed in the work. One of the most realistic models, in which the best coincidence of the curves of the anomalous and model magnetic fields is observed, is shown in Fig. 6. The discrepancy at the beginning of the profile of the observed and calculated curves of the anomalous magnetic field is due to the influence of the nearby island of Makanrushi. It follows from the simulation results that the anomalous magnetic field in the area of the volcano is caused by its construction, and not by deep roots. Despite the heterogeneity of the dredged material, the overwhelming part of the structure is rather homogeneous in the composition of its constituent rocks, which have direct magnetization. Based on the magnitude of the effective magnetization, such rocks can be high-K amphibole-bearing andesites typical of the rear zone of the Kuril-Kamchatka island arc.
The flat top of the volcano indicates that it once rose to sea level, and then experienced significant subsidence. Extensive underwater terraces about. Makanrushi are located at depths of about 120-130 m. This practically corresponds to the sea level in the Late Pleistocene, i.e. since the late Pleistocene, no significant subsidence has occurred in this area. Therefore, we can assume that the sinking of the flat summit of Smirnov Volcano to a depth of 950 m occurred before the beginning of the Late Pleistocene. The nature of the relationship between the edifice of Smirnov Volcano with sedimentary deposits of the bottom of the Sea of Okhotsk and deposits of the underwater slopes of Island. Makanrushi suggests that this volcano is one of the most ancient parts of the massif about. Macanrushi. Its age is at least Pliocene.
The Kuril Islands is a 1200-kilometer chain of 56 islands, stretching from the Kamchatka Peninsula to Japanese island Hokkaido. They form two parallel ridges, which are called the Big Kuril and Small Kuril.
All islands are part of the Sakhalin Region of the Russian Federation. Many of them have rich and picturesque nature. There are many volcanoes here.
There is evidence of battles with the Japanese in 1945. The economy of a few settlements is associated mainly with fishing and fish processing. These places have a huge tourist and recreational potential. Several islands in the South Kuril Islands are disputed by Japan, which considers them part of Hokkaido Prefecture.
In the northern part of Iturup Island, on the coast of the Sea of Okhotsk, there are extraordinary volcanic phenomena called White Rocks. They are composed of pumice or glass-like porous mass and stretch for 28 kilometers.
The ridges created by nature are of a fantastic appearance, cut by beautiful canyons. The coast near them is a beach covered with white quartz and black titanomagnetite sand. A view so extraordinarily beautiful natural object leaves a lasting impression.
On one of the islands there is an unusually beautiful bay called Craterna. It is a biological reserve. Its uniqueness lies in the isolation of flora and fauna from the surrounding nature. Here, along with those living at the bottom sea urchins several new species of animals have been discovered.
South-facing bay deep 56 meters away has a shallow entrance of 300 meters wide and juts out into the island for a kilometer. There is a 388-meter volcano in the bay Ushishir, the picturesque slopes of which are covered with dense vegetation, descending directly to the water.
This volcano island is the highest of the active volcanoes on the islands. Its height is 2339 meters and the correct cone shape, which is often compared with the outlines Japanese volcano Fuji.
At the base and on the slopes there are more than three dozen cinder cones. The volcano is located 70 kilometers from the Kamchatka coast and 30 kilometers from the largest North Kuril island, Paramushir. It is classified as a double stratovolcano, at the top of which there is an explosive crater 200 m deep and up to 1300 m in diameter.
The city of Severo-Kurilsk, located on the island of Paramushir, is its administrative center. It is home to 2587 people. After the war, on the basis of former Japanese enterprises, fish processing plants operated here.
Dwelling houses, schools, hospitals, etc. were built. In 1952, a tsunami with a wave height of 10 meters that arose as a result of an earthquake destroyed the city and adjacent settlements. In the 60s of the last century, the city was restored.
In 1982, on some of the islands belonging to the Lesser Kuril Ridge, a federal nature reserve was founded. Its purpose is to increase the number and preserve rare birds and marine animals.
Among them are the Red Book birds, as well as the local sea otter, seal, sea lion, northern fur seal, killer whale, gray dolphin and humpback whale. Most of the reserve is occupied by coniferous and deciduous forests. On its territory, there are nesting sites for seabirds and a rookery of a seal listed in the Red Book.
In the south of the island Iturup a natural reserve has been created, where there are two volcanoes, three mountain ranges, isthmuses, large picturesque lakes and many rivulets. The spruce and mixed forests covering the island are extraordinarily beautiful. They contain a huge amount of mushrooms and berries, there are thickets of bamboo.
There are unique plants like the huge Sakhalin champignon. Salmon fish spawn in Lake Krasivoe, which is 48 meters deep. You can get to the reserve through small airport and a pier in the Kasatka Bay.
This unique place on the planet got its name due to its ring-shaped form, which surrounds the Krenitsyn volcano, which is considered one of the largest in the world.
A lake with a volcano is located on a quiet and calm uninhabited island of Onekotan. The depth of the reservoir does not exceed a meter. This is an ideal place for connoisseurs of unspoiled nature who admire the surrounding landscapes while climbing a huge volcano.
This small volcano island with a constantly smoking upper cone is square in shape with a side of 3.7 kilometers.
The island is almost inaccessible due to its rockiness, it is possible to moor to it only by boat in one place in the absence of wind and waves. In this case, you need to focus on a beautiful 48-meter rock. The vegetation is sparse, there are mosses and grasses, alder bushes. Hundreds of thousands of birds gather here for bird colonies.
This is the name of the borderline and southernmost of the Kuril Islands. It is separated from Japan by two straits. The city of Yuzhno-Kurilsk is its main locality... In fact, the island consists of a chain of volcanoes, which are named after Golovin, Mendeleev and Tyat.
They are connected by reclaimed sandstone. The island has a rich flora and fauna. There are many thermal springs, unique volcanic lakes. One of them - Boiling, is considered the main South Kuril attraction.
This island is the largest in the northern part of the Kuriles. Its length about 120 kilometers, width about 30. It has a rich relief, consisting of mountain ranges, which are a chain of volcanoes, some of which are active. There are many forb meadows, many rivers, streams and lakes.
The forests are mostly willow. Wild rosemary and rhododendrons bloom beautifully, a lot of lingonberries, blueberries and other berries. The large river Tukharka is home to salmon fish. You can find brown bears, hares, rodents, sea otters, sea lions and seals.
This North Kuril island was an important military facility for the Japanese army. There was an 8,500-strong garrison with planes, tanks, guns, mortars, underground fortifications.
This 15-kilometer strait connects the Sea of Okhotsk with By the Pacific Ocean... He received the name of the Russian naval officer I.F. Kruzenshtern, who first crossed it in 1805 on the sailing ship "Nadezhda".
The strait is picturesque, along it there are uninhabited rocky and precipitous islands, and in the center there are Lovushki rocks, which are dangerous for seafarers. At its narrowest point, it is 74 kilometers wide. At maximum depth 1764 meters there are two 150-meter shallows.
On the slopes of the Baransky volcano there are unique thermal springs and reservoirs. On a rocky plateau, there is a geothermal station that generates electricity.
There are geysers, lakes, sulfur streams, baths with boiling mud. In the lake with the name "Emerald Eye" the temperature reaches 90 degrees. It feeds the picturesque four-kilometer rapids river Boiling with hot and sour water.
In one place, it breaks off with an incredibly beautiful 8-meter waterfall, the water temperature in which is 43 degrees.
Volcano! How much fear and excitement is contained in this word. Everyone knows that Russia is rich in the presence of active and extinct volcanoes on their territory. Most of them are located on the Kuril Islands and Kamchatka, 28 are active.
5 most famous volcanoes of Kamchatka
1) Undoubtedly, Klyuchevskaya Sopka takes first place due to its height, equal to 4750 m, and the diameter of the crater is about 500 m. This volcano is famous for the correctness of its shape (cone-shaped). The age is about 5000 years. Scientists have found that the volcano has erupted more than 50 times over the past 270 years. It is not surprising that he is considered to be the most active. Smoke or flashes of lava above it became commonplace for residents.
2) Volcano Tolbachik belongs to the Klyuchevskaya chain of volcanoes. It belongs to the kind Hawaiian volcanoes... It has two equal peaks - Ostry Tolbachik (3600 m) and Plosky Tolbachik (3100 m). As for the type of cone, it belongs to stratovolcanoes. Not so long ago, this place attracted tourists, and many people came here, but on November 27, 2012, an eruption occurred, after which travelers bypass Tolbachik. Much more interesting information about this and other volcanoes you will find on the website.
3) In the east of Kamchatka is located Kronotskaya Sopka- an active volcano (although it erupts quite rarely). Its height is 3550 m. The dimensions of the volcano are really impressive. For such a powerful creation of nature to be born, powerful eruptions had to happen. However, it was so in the past. One gets the impression that the volcano is divided into two zones: the top is covered with ice, and the bottom is covered with forest. Near the volcano there is Kronotskoye Lake, as well as the famous Valley of Geysers.
4) Active Avachinskaya Sopka, which is called Avacha among themselves, stands not far from Russian city Petropavlovsk-Kamchatsky. It would seem that it is a high and impregnable volcano (2700 m), but many comers gladly conquer it in the summer. The diameter of the crater is 400 m. In 1991, this volcano erupted for the last time, which caused significant damage to the surrounding area.
5) Shishel volcano is located in the northern part of the Kamchatka ridge and has a height of 2500 m. By its type, it belongs to the group of shield. It resembles an ellipse in shape. The volcano is not active, therefore it is classified as extinct.
6) Karymskaya Sopka is perhaps one of several volcanoes that can compete with Klyuchevskoy in terms of the number of eruptions. Scientists have recorded 20 eruptions over the past 50 years. The height of the volcano is 1536 m. It is located in the central part and belongs to the young.
The volcanoes of Russia are harsh giants who have repeatedly proved their great power, sweeping away everything in its path. In the eastern part of the country, echoes from recent eruptions can still be heard. Extinct or active volcanoes- they will always attract the eyes with their majesty and indescribable picturesque landscape.
Alaid is the highest of the Kuril volcanoes, the peak of which rises above the ground at 2339 m. It is located on the Atlasov Island, which stands alone in the north of the ridge and erupts every 30 to 40 years. The Alaid peak can be seen from the shores of Kamchatka in cloudless clear weather, it is believed that it was it in the 17th century that the discoverer of the peninsula Vladimir Atlasov described in his report.
Krenitsyn volcano
One of the most wonderful places in the world is the North Kuril island Onekotan in the Sakhalin region with its Krenitsina volcano (1325 m.) In the Tao-Rusyr caldera. This is the most big volcano in a volcano on the globe. Few manage to see this unique pearl of the Kuriles, especially after border guards left the island in 2005. And on the volcano itself, standing in the middle of a caldera filled with water, even fewer people have visited.
Kudryavy volcano
The world-famous Kudryavy Volcano (986 m.) Is located in the northeastern part of the Kuril island of Iturup, in the very center of the most beautiful Medvezhy ridge. The volcano has several craters. In calm weather, the height of vertical columns of gas and steam above them reaches 1000 m. This place is also known for the fact that a deposit of terribly expensive and little-studied metal with amazing properties has been discovered here. We are talking about rhenium, the last of the discovered non-radioactive chemical elements.
Volcano Tyatya
Tyatya is the most high volcano O. Kunashir is its unofficial symbol. It is located in the northeastern uninhabited territories, which were depopulated after the volcanic eruption in 1973. The eruption was so strong that volcanic ash reached the coast of about. Shikotan, located 80 km. from the scene of the giant mountain.
