The modification of spectral analysis especially intended for studying the disturbing functions of the atmosphere and ocean, as well as the observed polar motion (Wiener–Liouville spectrum), is used. ...The time series of the atmospheric disturbing functions obtained by the U.S. National Centers for Environmental Prediction (NCEP) of the International Earth Rotation and Reference Systems Service (IERS) for the period from January 1, 1980 to June 20, 2014 (
http://www.iers.org/.cs1?pid=43-1100116
) are analyzed. It is shown that the baric disturbing function contains a regular mode with a period of ~16 months; the contribution of this mode in the polar motion is estimated.
The Vp/Vs kinematic parameter for the Kamchatka seismic subduction zone has been long monitored on a regular basis. This has allowed estimating the behavior of the parameter and revealing its ...features during the precursory period and actual rupturing of the March 25, 2020 earthquake which occurred in the Pacific plate at the contact between the Pacific plate and the continental slope of Kamchatka. The March 25, 2020 earthquake with its high magnitude (
M
L
= 7.6,
M
W
= 7.5) is a rare enough event to occur in the Pacific plate. Knowledge of earth structure in the source region of the earthquake was updated based on the results of deep seismic sounding and continuous seismic profiling which was carried out in the area in the past. It was shown that the earthquake source area is at an inflection in the descending Pacific plate. The source area lies in the layer at the boundary between the asthenosphere and the crust and mantle. The layer is at depths of 30‒60 km and has lower Vp and Vs velocities. The inflection region along Kamchatka shows lower Vp/Vs values, which is a sign of extension along the plate. The source area is in the contact between the Pacific plate, which is subducting under the southern end of Kamchatka, and the North Kuril Islands, as well as the Sea-of-Okhotsk plate. The region shows a distinct change in the anomalous values of the parameter from lower to higher, with the latter being typical for compression. Our study has allowed estimating possible regions of tension and compression in the geological medium.
—
The dynamics of the volcanic activity, magmatic feeding system, accumulation, movement, and composition of magmas, and structure of the roots of the Northern group of volcanoes (NGV) in Kamchatka ...are considered. The results of monitoring the field of the ratio of seismic
P
- and
S
-wave velocities, the
V
P
/
V
S
parameter in the region of the Klyuchevskaya volcanic group based on the data of the volcanic earthquakes registered by a network of telemetric seismic stations are presented. The parameter changes in space and time during the periods of volcanic activity development. Each segment of the volcanic structure and period of activity is characterized by the own behavior of the field of
V
P
/
V
S
values. In the intermediate magmatic chamber, low
V
P
/
V
S
values are observed beneath the Klyuchevskoi volcano at a depth of 8 to 10 km and beneath Plosky Tolbachik at a depth of 3 to 5 km, which is related to the state of the substance and temperature in these areas, and the entry of a new melt portion of magma and the fluid-gas component from the crust and the mantle. The relation of volcanic earthquakes and earthquakes in the focal zone of Kamchatka, i.e., the ratio of the subduction zone (the sinking Pacific Ocean Plate) and the feeding source of volcanoes, is considered. It is shown that the Klyuchevskoi peripheral chamber is not the only area feeding the NGV. According to the values of the
V
P
/
V
S
parameter, the volcanoes have different magma compositions, which is determined by the physicochemical and temperature features of the medium. In our opinion, the feeding area of volcanoes from the Northern group is a neutral layer that we have identified.
Based on the seismological, geodynamic, and seismotectonic data on the strongest series of earthquakes in 2009–2017 in Central Italy, which were collected by many researchers, mostly Italian, the ...tectonic position of these events is determined and the seismic history of the region over more than 2000 years of observations of seismic manifestations in Italy is traced in the context of the strong events of the beginning of the 21st century. The aftershock processes of these earthquakes are investigated and, as a result, the possibility of a series of strong aftershocks of the earthquake of October 30, 2016 (
M
W
= 6.6) is predicted in advance of the actual occurrence of these events on January 18, 2017.
Polar motion under anisotropic random load Tsurkis, I. Ya; Kuchai, M. S.; Sinyukhina, S. V.
Izvestiya. Physics of the solid earth,
2014/1, Letnik:
50, Številka:
1
Journal Article
Recenzirano
The probabilistic approach to the description of the Chandler wobble is expanded to the case of anisotropic random load. The polar motion is treated as a two-dimensional (2D) Markov process—the ...solution of the Liouville equation—with discrete time. It is shown that with a sufficiently large time step Δ, the polar motion can be considered as an isotropic process irrespective of the particular ratio between the eigenvalues of the diffusion matrix, which characterizes the right-hand side of this equation (random load). The problem of reaching the boundary of the domain
E
min
,
E
max
by the energy of the pole
E
(
t
) =
x
1
2
+
x
2
2
is considered. With a time step Δ of 1 year and the length of the time series of the observations
N
= 150, the correction for anisotropy to the total probability
P
* of a drop by a factor of five in the amplitude of the Chandler wobble
A
= √
E
does not exceed 10
−2
, and the probability
P
* is above 0.3 (if the
Q
-factor of the mantle is below 500). Thus, it is demonstrated that the observed variations in amplitude
A
(
t
) can be explained in the context of the probabilistic approach without hypothesizing the isotropy of the random load.
To demonstrate a novel and effective surgical technique for the treatment of refractory cerebrospinal fluid rhinorrhoea after skull base surgery. The novel surgical technique is described and the ...findings of a review of relevant world English-language publications are reported.
A 44-year-old woman, otherwise fit and well, presented with more than a 2-year history of right-sided facial pain. A diagnosis of classical trigeminal neuralgia was made. Surgical treatment was undertaken with a retromastoid suboccipital craniotomy. Post-operatively, the patient showed signs of right-sided cerebrospinal fluid rhinorrhoea which was recalcitrant. In light of a continuous leak and several hospital admissions, a novel technique was performed whereby the eustachian tube orifice was obliterated using an endonasal endoscopic approach. The technique proved to be successful, with no further leakage.
Endoscopic obliteration of the eustachian tube using a double seal technique is a simple, safe and effective procedure in the treatment of a refractory cerebrospinal fluid leak.
Tectonophysical studies are conducted in South Sakhalin for identification of temporal–spatial changes in the geodynamic settings of the formation of the local structures. Analysis of the field data ...reveals 11 local stress state (LSS) in the large newest megastructures, which were formed on geological basement of different ages. The parameters of the tectonic stresses are significantly distinct in each LSS, especially the orientations (up to reindexation) of the compression and extension axes in different fault wings. Tectonic stresses of two ages and constant latitudinal and horizontal compression axis are reconstructed. The earlier cofold shear stress field with a horizontal and longitudinal extension axis is post-Miocene and the later stress field of the reversed fault with a vertical extension axis is orogenic. The LSSs reconstructed for the first time by the displacement vectors on slickensides, along with the data on the earthquake mechanisms, substantiate the reindexation of the horizontal extension axis with the vertical intermediate axis of major normal stresses at the postfold orogenic stage of evolution of the territory. These results are in agreement with previous data on the transformation of the dextral to reverse thrust displacements along the longitudinal fault systems. The young stress field is more confidently interpreted in the activation fault zones, which limit the orogenic blocks, whereas the traces of cofold deformations without younger orogenic stress fields better remain inside the blocks which are composed of older and strongly dislocated Mesozoic rocks.
A study on morphology and morphometry of Haemonchus contortus Kuchai, J.A. (University of Kashmir, Srinagar (India). Dept. of Zoology); Ahmad, F. (University of Kashmir, Srinagar (India). Dept. of Zoology); Chishti, M.Z. (University of Kashmir, Srinagar (India). Dept. of Zoology) ...
Pakistan journal of zoology,
12/2012, Letnik:
44, Številka:
6
Journal Article
Recenzirano
Haemonchus contortus has posed a great problem to researchers and has created confusion among them regarding its identification. In this study an attempt has been made to study the morphology and ...morphometry of Haemonchus contortus recovered from the ruminants and to relate it with some parameters like study area, host, intensity, methodology, age and sex of the host. It was observed that all these factors have some minor intraspecific effects on the morphology and morphometry of the parasites. These variations were of minor importance because they were found within the range of similarity and were not good enough to label it as a new species as was expected. Also some of the parameters with regard to morphology and morphometry of this parasite were described for the first time which were not described by the previous authors and these could be of great taxonomic importance for the identification of this parasite which is being confused many times and is being labeled a new species.
The authors comment on features of formulation and structure of input data for the inverse problems used in rock mechanics to estimate state and properties of natural and anthropogenic objects at ...various spatial scales. The article gives examples of using solutions of inverse problems in coal bed degassing monitoring, based on data on changes of pressure in hydraulic props in the overlying bed, and in assessment of deformation parameters of inclusions, based on data of uniaxial compression tests of artificial heterogeneous specimens.
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