Applied Aspects of Different Frequency Bands of Seismic and Water Acoustic Investigations on the Shelf

Izvestiya, Atmospheric and Oceanic Physics - This article focuses on the study of the information value of offshore technologies based on the generation of acoustic signals in water in a wide...     

Estimation of Elastic Stress-Related Properties of Bottom Sediments via the Inversion of Very- and Ultra-High-Resolution Seismic Data

Izvestiya, Atmospheric and Oceanic Physics - This paper provides an overview of several seismic inversion approaches and their application to very- and ultra-high-resolution marine seismic...     

The evolution of slump-induced destruction of Kukuy Griva slope (Lake Baikal) revealed on the base of the data of seismic and acoustic surveys

As a result of careful interpretation of the data of recent seismo-acoustic surveys, two major seismic complexes were identified in the structure of the upper sedimentary section of the north-western slope of Kukuy Griva (ridge). They are composed of several inner seismo-facies, which are very characteristic and separated with well-expressed regional reflector. Seismic and acoustic data revealed evidences of numerous landslide processes which were different in age and peculiarities of manifestation. For the first time, detailed schemes of seismo-facies distribution are compiled for major seismic complexes at the area. The boundary between seismic complexes is dated as 150 thousands years. It is shown that sliding was more intensive during Late Pleistocene and Holocene, reflecting activation of tectonic movements in this part of Baikal rift system.     

The Structure of the Sedimentary Cover of the Kandalaksha Gulf,White Sea,from Seismoacoustic Data

The geological structure of water areas adjacent to the White Sea biological research station of Moscow State University (Rugozero Bay and Great Salma Strait; both are parts of the Kandalaksha Gulf, White Sea) was studied for the first time based on the seismoacoustic data. The morphology of the top of the Achaean basement, the structure of the Quaternary sedimentary cover, and the bottom topography were investigated. The sequence of glacial deposits dated back to the last glaciation and the compound sequence consisting of glaciolacustrine, glacial-marine, and marine sediments are distinguished. The spatial locations and changes of their thicknesses are considered. It is shown that the recent bottom topography is controlled by predominantly NW- and NE-striking faults that run through the entire sedimentary sequence, including the Holocene sediments.     

On the focal layer,seismicity and volcanicity of the Kurile-Kamchatka zone

The general relationships of the structure of the Kurile-Kamchatka zone are examined. The chain of volcanoes forms a true arc with the radius of 1884 km. The focal layer of earthquakes along the whole arc extends to depth with an angle of 48° ± 5°, and is a part of the surface of a circular cone. The energy of earthquakes at intervals of depth 0–100 km, 101–300 km, and 301–650 km is on the average distributed equally along the whole arc and in time. The activity of volcanoes of the whole zone in time is also rather evenly distributed. The energy lost from the earth’s interior during the volcanic eruptions is not less than the energy emitted as elastic waves during tectonic earthquakes.     

Forecasting volcanic eruptions from seismic data

An increase in cumulative seismic strain release from volcanic earthquakes prior to eruptions of Bezymyanniy Volcano in 1955–1961 and Sheveluch Volcano in 1964 in Kamchatka, and of Tokachi-dake Volcano on Hokkaido Island in 1962 occurred in accordance with a hyperbolic law. The relationship obtained may be universal for andesite volcanoes. Knowing the law of the increase of cumulative seismic strain and carrying out continueus observations of the seismic regime of andesite voleanoes makes it possible to prediet time and energy of eruptions. By observation of volcanic earthquakes it is also possible to predict the place and time of the occurrence of lateral craters.     

Incoherent radiation from relativistic electrons with power energetic spectrum

It is shown that an incoherent high-frequency radiation from an ensemble of relativistic particles with the power energy distribution is described by a certain general expression which covers practically all the cases of particle radiation in random electromagnetic fields of cosmic radiation sources.     

Helium and other noble gases in gas-hydrate sediments of the Håkon Mosby Mud Volcano

He, Ar, Ne contents and ³He/⁴He, ⁴He/²⁰Ne, and ⁴⁰Ar/³⁶Ar ratios in gas-hydrate bearing sea-floor sediments of the Håkon Mosby Mud Volcano show that Ne, Ar, and part of He are atmospheric. Nonatmospheric, deep He (³He/⁴He=0.9???10^-8) is present in all samples. Helium isotopic composition suggests that its origin is uniform, crustal (radiogenic) and, probably, connected with mud volcano gases. Apparently deep helium is residual gas that remains in isolated volumes after hydrate formation. Measured helium content in hydrate gases is very low: 0.5–10?ppm. but in one particular sample it is very high: 7080?ppm.     

Prediction and characteristics of the 1975 eruption of Tolbachik volcano,Kamchatka

According to a long-term prediction. Tolbachik volcano was expected to erupt with a 0.7 probability, some time in the period 1964–1978. An eruption of Tolbachik commenced at 21.45 GMT on July 5, 1975. It took place on the southwestern Hank of the volcano at an altitude of 880 m a.s.l. about 18 km from the central crater. An earthquake swarm preceded it. The place and time of eruption were predicted three days belore it began on the basis of epicenter locations and characteristics of recorded seismic activity. During the period July 5–28 gases and incandescent magma were continuously ejected to a height of 2,000 m above ground level. Ash clouds rose to a height of 6 to 8 km, with a train of ash extending over a horizontal distance of 300 km. The velocity of jets from the crater was about 200 m/see. During the first days of the eruption the quantity of materials erupted and the eruption power amounted to 1.25 · 10⁵ kg/see and 2.1 · 10¹¹W, respectively. The vertical growth of the scoria cone was consistent with the lawH=2.15³√vt, where the time and height are expressed in seconds and meters, respectively. The mouth of the volcano conduit was estimated to be 12 m in diameter. Lava began to erupt at 22^h23^m on July 28. During the period July 5–31 about 3 · 10¹¹ kg of magmatic material, consisting of ash, scoria and lava, was erupted onto the earth’s surface. The energy released over the period of eruption accounted for 5 · 10¹⁷ J.     

Tommotian (Lower Cambrian) stratigraphy and fossil fauna communities in the Kiya River section (Kuznetsk Alatau)

The lower Ust’-Kundat Formation has been studied in detail in a section along the Kiya River (Kuznetsk Alatau, Altai-Sayan folded area). The section was deposited during the Tommotian stage and is a stratotype for the Lower Cambrian Ust’-Kundat sequence comprising several members of the Ust’-Kundat Formation. Member 2 contains newly discovered and previously known species of archaeocyathids near its top found stratigraphically lower than the oldest known archaeocyathan assemblage of the Nochoroicyathus mariinskii biozone. The found archaeocyaths cannot be dated precisely and may have either Tommotian or Atdabanian ages. Small shelly fossils from the same section cover a large stratigraphic range as well. The findings call for updating the age of the upper Ust’-Kundat sequence and the Tommotian upper boundary in the regional stratigraphy of the Altai-Sayan folded area.