Velocity Sections Research Articles

Relation of shear wave velocity variations with depth for different lithologies: A contribution towards mitigating the region's seismic risk

The state of Uttarakhand in India lies in a highly seismically active zone, therefore earthquake re- sistant design criteria have been followed for major construction practice in this region. One of the major inputs for earthquake-resistant design is average shear wave velocity (VS ) at 30 m depth. In the present work, at twenty-six different sites, the Horizontal to vertical spectral ratio (HVSR) technique and multichannel analysis of surface wave (MASW) is used for joint analysis to obtain a one-dimensional velocity model that supports both the HV spectrum and dispersion curve obtained from HVSR and MASW methods, respectively. Shear wave profiles obtained at various sites are compared with the bore log data obtained from drilling and it clearly shows that the (VS ) for the same formation have a strong dependence on the depth at which it occurred. Data from twenty- four shear wave profiles have been used to prepare a linear regression relation of (VS ) for different lithological formations with respect to their depth of occurrence. Root mean square error obtained from the developed relationship for various lithologies clearly shows that the results are fairly well within the range of acceptance. The developed relations have been further validated by calculating Vs profile from bore log data obtained at two new location sites that are not included in the data set used for the preparation of regression relations. A comparison of two velocity sections clearly shows that the velocity profile computed from regression relation matches closely with that obtained from the seismic survey and thereby establishing the efficacy of developed regression relationship for its practical implementation. This developed relation allows soil type classification for zoning purposes.

Interactions between the North Brazilian Undercurrent (NBUC) and the Southwest Atlantic Margin. Implications for Brazilian shelf-edge systems

Western boundary currents influence the global ocean circulation and climate, whereas it locally reaches out differently to the continental margins. This study investigates the response of the North Brazilian Undercurrent (NBUC) over their interactions with the eastern and northern margins of the northeastern Brazil. The data set comprises regional bathymetry, in situ current measurements, CTD profiling, and simulations of oceanic currents using a regional model (CROCO). The physical analysis focuses on the months of February (austral summer) and August (austral winter). Horizontal and vertical structure of current velocity, temperature and salinity were correlated using maps and bathymetric profiles along the critical pathways of the NBUC. The eastern and northern margins are narrow and retracted with widths up to 40 km and steep upper continental slopes (14°). These margins are separated by the Touros High, which extends eastward up to 80 km offshore, with a shallow shelf (most parts are < 10 m) of approximately 55 km wide. The vertical sections of velocity show the NBUC shifting onto the Touros shelf in August and show that the strong trade winds during the austral winter handle the alongshore current circulation of this region. In the northern margin, the recirculation of the NBUC disturbs the base of the thermocline and part of these current fluxes toward the outer shelf region. The different patterns of the NBUC affect the sedimentary and ecological characteristics of eastern, Touros and northern outer shelves. Besides, the slope and outer shelf morphology might contribute to events of current-driven nutrient-enrichment and mixing processes at the base of the mixed layer. These results support the evidences that the western boundary current interactions by eddies and jets with the margin control the morpho-sedimentary and environmental conditions of the Brazilian outer shelf ecological system corridor.

Velocity and Density Cross Sections of the Upper Part of the Lithosphere within the North Urals Segment

Velocity and Density Cross Sections of the Upper Part of the Lithosphere within the North Urals Segment

Altai earthquake (2003) fault zone velocity structure - case study

This paper presents the results of seismic surveys in the epicentral zone of the Alaty earthquake (2003), conducted in the summer of 2021. The object of research was a fractured zone, which on the surface manifests itself as a rupture of the earth's surface with a width of 3-5, a depth of up to 1 and a length of about 200 meters. The main objective of the 2021 research was to study changes in the structure of the velocity section in the rupture zone, presumably associated with the degradation of the permafrost. As a result of processing records of refracted waves, a seismotomographic model for P-waves was obtained, and a seismic boundary was identified by the GRM method. As a result of processing surface wave recordings by MASW, one-dimensional S-wave sections were obtained for the left and right parts of the section. Interpretation of the results showed the presence of a huge unfrozen zone with a thickness of about 30 meters, which indicates an active process of degradation of the permafrost in this area.

Особенности оценки сплошности свай методом сейсмоакустической дефектоскопии

Introduction. The authors present the results of pile continuity studies conducted using seismoacoustic defectoscopy. Tests were conducted in the Rostov region and Moscow. Reflectograms of tested piles, as well as the subsequent interpretation and confirmation of the design length and continuity of the pile shaft are provided. Materials and methods. The research results were obtained using Spektr 4.3, whose operating principle is based on the theory of elastic wave propagation. This device is used for the recording of the pile response to external impacts with the preset pulse parameters. The signal is recorded by means of an accelerometer sensor, connected to a special computer with the software for the digitization and interpretation of incoming information. Data processing results are presented in the form of computer graphic images (reflectograms), which show the pile length, continuity, damages (if any) and their location. Results. The dependence between soil homogeneity and signal purity has been identified. At the interface between two types of soils that are different in density, the sound wave was reflected and partially passed further, creating characteristic peaks of false defects. To eliminate false defects, studies of layered soils are necessary. Conclusions. The results confirm the effect of the soil homogeneity on signal purity. The higher the heterogeneity of the soil structure, the bigger the number of false peaks that the reflectogram demonstrates. A prerequisite for the correct interpretation of the results of pile continuity testing is the study of the geological section and preliminary instrumental identification of the ultrasound propagation velocity for each individual pile.

Algorithm for accurate velocity analysis of 1D acoustic reflection and transmission responses by projection constrained multi-physics inversion

Velocity analysis is critical in seismic data interpretation. In sedimentary environment, 1D geometry is a reasonable assumption. Velocity analysis under such assumption has been done through the interpretation of either reflection or transmission responses. Recently, Marchenko method has also been applied to provide 1D velocity model from reflection data. However, none of the previous researchers attempted to invert the velocity model from combined physics from the reflection and transmission data with a projection constraint. The projection constraint is computed from the determinant of matrices of dot products of the velocity models. Although, the MATLAB code for the forward responses is given, the algorithm for performing the multi-physics inversion of 1D reflection and transmission data, with projection constraint, is presented. The concept is tested on two different velocity model examples with varying overburden thicknesses and layer thicknesses. Results are consistent even with up to 5% random noise. It is also worthy of note that while the near-surface velocity section remains less affected in the reflection response data, the deep-subsurface velocity values are equally resilient from the transmission response. This presents a much-desired complementary benefit for velocity analysis from a multi-physics interpretation.

Efficient Recurrent Neural Network for Classifying Target and Clutter: Feasibility Simulation of Its Real-Time Clutter Filter for a Weapon Location Radar

The classification of radar targets and clutter has been the subject of much research. Recently, artificial intelligence technology has been favored; its accuracy has been drastically improved by the incorporation of neural networks and deep learning techniques. In this paper, we consider a recurrent neural network that classifies targets and clutter sequentially measured by a weapon location radar. A raw dataset measured by a Kalman filter and an extended Kalman filter was used to train the network. The dataset elements are time, position, radial velocity, and radar cross section. To reduce the dimension of the input features, a data conversion scheme is proposed. A total of four input features were used to train the classifier and its accuracy was analyzed. To improve the accuracy of the trained network, a combined classifier is proposed, and its properties are examined. The feasibility of using the individual and combined classifiers as a real-time clutter filter is investigated.

Microtremor Survey Method: A New Approach for Geothermal Exploration

Geothermal resources are a type of sustainable and green energy, which can play an important role in emission peaks and carbon neutrality. Determining the best development target area is key to resource development and geophysical methods are commonly used for this purpose. Owing to serious human and industrial interference, the microtremor survey method is often adopted for geothermal exploration in urban areas. It is a passive source method, which is non-invasive and environmentally friendly. In this method, the Rayleigh wave dispersion curve is extracted using spatial autocorrelation based on the vertical component signal at the observation station. A genetic algorithm is used to invert the dispersion curve of one survey point to obtain strata parameters such as layer thickness, S-wave velocity, and density. It provides critical parameters for the cap layer and reservoirs for geothermal exploration. For a chain microtremor measurement, a two-dimensional (2D) apparent S-wave velocity section can be generated. The apparent S-wave velocity is calculated from the phase velocity using the following empirical method: the 2D apparent S-wave velocity section helps to identify the buried channel for heat flow and track the irregular shapes of the reservoirs or cap layers. It has been verified that the microtremor survey method is reliable and accurate compared with borehole materials. As a newly developed non-invasive geophysical method, it can be widely used in geothermal exploration.

КОРРЕЛЯЦИЯ АКУСТИЧЕСКИХ ХАРАКТЕРИСТИК И ВОЗРАСТА БАЗАЛЬНЫХ ГОРИЗОНТОВ КАЙНОЗОЙСКОГО ОСАДОЧНОГО ЧЕХЛА ЯПОНСКОГО МОРЯ

Velocity sections and acoustic characteristics of the sedimentary cover of the Central (Japan), Yamato (Honshu), Tsushima basins and the Kita-Yamato trough of the Sea of Japan, as well as the rocks of the basement and Cenozoic cover of the Yamato Upland were studied. A comparative analysis of similar characteristics of the Cenozoic basins of the South China and East China marginal seas was carried out. The relationship between the acoustic properties (P-wave velocity - Vp) of the basal horizons and the age of the Cenozoic cover in the above basins were analyzed. It has been substantiated that the values of Vp = 3.0-3.6 km/s are an acoustic characteristic of Paleocene-Eocene sedimentary strata. According to the studies performed, the basal layers in the inferred depocenters of the Sea of Japan basins (Central, Yamato, Tsushima) have Vp = 3.0-3.3 km/s, which indicates the Paleocene-Eocene age of the beginning of their formation.

Mantle gravity anomaly and recent activation in the territory of Ukraine

The study of the zones of modern activation on the territory of Ukraine for a long time was carried out using a complex of geological and geophysical methods. Each of them is not without its drawbacks. The results obtained allowed us to assume that the determination of the mantle anomaly of the gravitational field can be eliminated their significant part and serve as a unified criterion for identifying the zones of modern activation. For this, it is necessary to improve the methodology for calculating the effect of the earth’s crust, supplementing it with taking into account the degree of catagenesis of part of the rocks of the sedimentary layer, the effect of increased concentrations of ore minerals in the depths of regional magnetic anomalies, etc. Thus, a more accurate calculation of the effect along the DSS profiles can be achieved. In addition, it is necessary to ensure the determination of the gravitational effect of the crust in the area between the profiles. Kriging technology was used to solve this problem. It allows you to calculate the predicted values of the parameter using those known in other points and to estimate the error of the result. In our case, the usual kriging option was sufficient. To determine the errors, instead of the commonly used variograms, a comparison of data on one of the DSS profiles with those calculated by kriging from information on adjacent profiles was used. The resulting error turned out to be quite understandable, taking into account the errors of the initial data, and acceptable for using the results for mapping the mantle gravity anomaly, and, consequently, the zones of modern activation of Ukraine. The constructed map demonstrates some difference in the location of the anomaly (and, accordingly, the recent activization — RA zones) from the previously established one. In particular, the anomaly is absent in the Desnyanskiy basin of the Dnieper-Donetsk depression. Actually, the gravitational mantle anomaly was absent there before, the spread of the RA zone into the basin was indicated by other criteria of low reliability. It is possible to record the presence of an anomaly in the territory between the Azov and Donbas regions, where it was not previously diagnosed. This result still needs to be supported by additional data. First of all, due to the observed significant discrepancies between different variants of velocity sections along the DSS profiles.

Terrain Effects on Regional Precipitation in a Warm Season over Qinling-Daba Mountains in Central China

The terrain effects of Qinling–Daba Mountains on reginal precipitation during a warm season were investigated in a two-month day-to-day experiment using the Weather Research and Forecasting (WRF) model. According to the results from the terrain sensitivity experiment with lowered mountains, Qinling–Daba Mountains have been found to have an obvious effect on both the spatial-temporal distribution and diurnal cycle of reginal precipitation from July to August in 2019, where the Qinling Mountains mainly enhanced the precipitation around 34° N, and the Daba Mountains mainly enhanced it around 32° N at the time period of early morning and midnight. Horizontal distribution of water vapor and convective available potential energy (CAPE), as well as cross section of vertical velocity of wind and potential temperature has been studied to examine the key mechanisms for these two mountains’ effect. The existence of Qinling Mountains intercepted transportation of water vapor from South to North in the lower troposphere to across 34° N and caused an obvious enhancement of CAPE in the neighborhood, while the Daba Mountains intercepted the northward water vapor transportation to across 32° N and caused an enhanced CAPE nearby. The time period of the influence is in a good accordance with the diurnal cycle. In the cross-section, the existence of Qinling Mountains and Daba Mountains are found to stimulate the upward motion and unstable environment effectively at around 34° N and 32° N, separately. As a result, the existence of the two mountains lead to a favorable environment in water vapor, thermodynamic, and dynamic conditions for this warm season precipitation.

Experimental investigation on effect of stratification of bimodal settling slurry on slurry flow friction in pipe

Pipe flows of bimodal aqueous slurries of two fractions of sand (coarse sand of particle mass-median size of 1.56 mm and fine-to-medium sand of mass-median size of 0.22 mm) are tested in a laboratory loop (pipe internal diameter of 100 mm) to study the frictional loss reduction due to the presence of the finer fraction in the bimodal slurry. The tested bimodal slurry flows (mean solids volumetric concentrations of 0.23, 0.30, 0.45 respectively) are compared with their coarse slurry counterparts (flows of one-species slurry at solids concentrations of 0.17, 0.24, 0.34 respectively, without the finer fraction) in tests which include measurements of solids distribution in a pipe cross section and measurements of local velocity of solid particles at the bottom of the pipe. The tests reveal a presence of a sliding bed in the bimodal slurry flow and a development of a thin fine-particle layer at the interface between the bottom of the sliding bed and the pipe wall. The measured difference in local velocities of fine particles and coarse particles at the bottom of the pipe indicates that the fine-particle layer effectively separates the sliding bed from the pipe wall hence it is responsible for the reduction of sliding friction at the wall and reduction of the overall frictional loss in bimodal flow compared to its coarse slurry counterpart. The identified loss reducing mechanism can improve modelling of stratified settling slurry flows composed of solids fractions of different sizes interacting with each other in a pipe.

Building a geothermal formation model using microtremor array measurement

A comprehensive understanding of the internal structure and construction of a geomechanical formation model play an important role in developing and using geothermal resources. Formation models help in identifying the channel and cycling modes of the heat flow. Due to urban sprawl and development, constructing a formation model of geothermal resources based on data from traditional geophysical methods is challenging. The microtremor survey method (MSM) is adopted to obtain critical information in Jimo, which is famous for rare seawater geothermal resources in China. Three microtremor survey lines are deployed to identify subsurface structures up to 2 km into the ground. Dispersion curves of Rayleigh waves with frequencies from 0.4 to 10 Hz are extracted using the spatial autocorrelation method. An empirical equation is adopted to obtain the apparent shear wave (S-wave) velocity of each survey point and to plot the apparent S-wave velocity sections. The obtained sections reveal the development of two interacting faults, which form a channel for the heat-flow cycle. Two conceptual models are established to depict the formation and cycling modes of seawater geothermal resources in Jimo, based on the results and analysis. Our model will help verify the geothermal system and scientifically guide the development of unique geothermal resources. Moreover, the developed model verifies that MSM is effective and dependable for identifying fracture zones and strata.

VOLUMETRIC AND SPATIAL SEGMENTATION OF THE TIEN SHAN LITHOSPHERE ACCORDING TO GEOPHYSICAL DATA

This article consolidates the results of studying the deep structure of the lithosphere of the Central Tien Shan, which aimed to identify the main tectonic elements in its geophysical models. We have compared the structural and geological data with the information on the deep structure obtained by geophysical methods and from the positions of earthquake hypocenters in the study area. According to geological concepts, the Tien Shan orogenic belt is characterized by longitudinal and transverse segmentation. The boundaries of the Northern, Middle, Southern Western and Eastern segments of the Tien Shan are deep-seated fault structures. In deep faults and channels of heat and mass transfer, endogenous processes are localized. High-velocity, geoelectrical and thermal models consider such faults and channels as contrasting objects that can be referred to as indicators of these processes.Our analysis of the locations of earthquake hypocenters from NNC, KNET, CAIIG, KRNET, SOME catalogues shows that seismic events are strongly confined to the fault zones and the boundaries of large blocks. A correlation between the anomalies of geophysical fields suggests the degree of inheritance of tectonic structures and the boundaries of the main tectonic segments of the Tien Shan. To compare the crustal and upper mantle heterogeneities reflected in different geophysical fields, we have analyzed seismic tomographic sections based on volumetric seismotomographic models geoelectric and velocity sections along profiles across the main tectonic elements of the study area. The sections are used to identify the zones with relatively low (i.e. reduced) seismic wave velocities and detect the deep-seated longitudinal segmentation of the folded belt. Objects showing anomalous seismic wave velocities are found in the seismotomographic sections at all the depths under consideration. The most contrasting differences in the velocities of P- and S-waves are typical of the depths of 0-5 km and 50-65 km, showing the most clearly observed Northern, Southern and Western segments of the Tien Shan. In general, the velocities of P- and S-waves at the Northern Tien Shan are higher than those at the Middle and Southern segments. We have analyzed the distribution of geoelectric heterogeneities identified from magnetotelluric sounding data in order to determine the boundaries of the main tectonic elements that are considered as the zones of increased electrical conductivity confined to the boundaries of the fault structures. The distribution of earthquake epicenters clearly reflects the segmentation of the Tien Shan into the Northern, Middle and Southern segments and shows the Western and Eastern Tien Shan relative to the Talas-Fergana fault. Ourstudies of the crust and the upper mantle of the Tien Shan have confirmed that the abovementioned tectonic segments have differences in their deep structures Based on a comprehensive analysis of the study results, we can qualitatively identify a relationship between the distribution of the velocity and geoelectric heterogeneities in the crust and upper mantle, seismicity and the stress-strain state of the crust.

Lifetime measurement in picoseconds for the excited states of 129Cs

The high-spin states of 129Cs were populated using the fusion-evaporation reaction 124Sn(11B, 6n)129Cs. We have studied the nuclear structure properties – signature splitting and reduced transition probabilities (B(E2)) – of many excited states in 129Cs. Lifetimes in picoseconds were measured using the Doppler Shift Attenuation Method (DSAM). We employed two gating procedures, Gating on transition above (GTA) and Gating on transition below (GTB), to obtain the experimental results consistently. We carefully analyzed the data by incorporating the effects related to nuclear reaction, e.g., change in the velocity and cross section of residues when moving in a medium. Theoretical investigations were carried out for two yrast bands – a positive-parity based on πg7/2, and another negative-parity based on πh11/2 – using the single quasi-particle rotor model (PRM). For both bands, we found the same deformation parameter values ϵ≃0.14, |γ|=18∘ (Lund convention) by simultaneously matching the experimental and theoretical results for the signature splitting and B(E2) values. Most of our results are new and reasonably well understood theoretically.

Hydraulic Modelling of Different Working Regimes in Water Pipeline. Case Study: Mihaliq – Water Treatment Plant “SHKABAJ”

In the flow through the pipes, we have unstable movements when, due to the closing or opening of the valve or other hydraulic equipment, the speed of movement of the liquid changes. The change in velocity causes inertial forces to arise in the liquid which cause pressure changes in the flow. The phenomenon characterized by these pressure changes is called hydraulic water hammer.&#x0D; The hydraulic shock can be called the increase or decrease of the flow pressure in the pipe caused by the change in time (in any section) of the flow velocity.&#x0D; The objective of this paper is to provide information and resources to assist water company management and their staff in identifying and implementing opportunities to reduce energy use. Case study is Pumping Station in Milloshevo managed by Regional Water Company “PRISHTINA”.

Hydraulic Modelling of Different Working Regimes in Water Pipeline. Case Study: Mihaliq – Water Treatment Plant “SHKABAJ”

In the flow through the pipes, we have unstable movements when, due to the closing or opening of the valve or other hydraulic equipment, the speed of movement of the liquid changes. The change in velocity causes inertial forces to arise in the liquid which cause pressure changes in the flow. The phenomenon characterized by these pressure changes is called hydraulic water hammer.&#x0D; The hydraulic shock can be called the increase or decrease of the flow pressure in the pipe caused by the change in time (in any section) of the flow velocity.&#x0D; The objective of this paper is to provide information and resources to assist water company management and their staff in identifying and implementing opportunities to reduce energy use. Case study is Pumping Station in Milloshevo managed by Regional Water Company “PRISHTINA”.

Evaluating the Earth Subsurface for Civil Engineering Site Characterization in Agege, Southwest Nigeria Using Integrated Geoelectrical and Multichannel Analysis of Surface Wave (MASW)

A geophysical investigation involving 1D Vertical Electrical Sounding (VES), 2D Electrical Resistivity Imaging (2D ERI) and Multichannel Analysis of Surface Wave (MASW) has been carried out at Agege, Lagos, Nigeria with a view to delineating the subsurface stratigraphy and locate some competent strata/stratum for founding civil engineering structures. Six (6) 200 m long traverses were established within the study area. Along these traverses, 2D ERI were carried out adopting Wenner electrode configuration. Vertical Electrical Sounding (VES) adopting Schlumberger electrode array were carried out at selected points along profiles 1, 2 and 3 to determine the lithological sequence at depth. MASW data also were acquired along traverses 1, 2 and 3. The data were processed and the result yielded interpretable 2D resistivity structure and geoelectrical parameters (layer resistivity, thicknesses and depth) from the VES. The interpreted VES results were used to generate geoelectric section while the MASW resulted in 2D velocity sections. Three subsoils including topsoil, clay and clayey sand/sand were delineated beneath the study area. The resistivity and thickness range of the layers are; topsoil (34.0-54.6 ohm-m, 0.9 – 1.7 m), clay (10.3 – 17.7 ohm-m, 8.9 – 12.3 m) and clayey sand/sand (48.9 – 323 ohm-m) while the S-wave velocity range for the subsoil falls between 40 – 500 m/sec.

Methods for online measurement and control of section deviations during hot rolling of wire rod and bars

In the joint project PIREF, the metal forming group of the University of Duisburg-Essen has collaborated with the University of Applied Sciences Ruhr-West Mülheim (Ruhr), the University of Siegen, EMG Automation GmbH and SMS group GmbH to develop sensors, for an online measurement of material velocity and cross section as well as control models for the rolling process of wire rod and bars. The University of Duisburg-Essen provided a metal forming process model for the rolling process to assess the influencing parameters on the rolled section precision. A technique was found to segregate height- from width- influencing parameters from a measured cross-sectional area and actual roll gap. With this measuring technology and with help of the process model, rules for control of the rolling process to achieve close tolerances were obtained. The modelling was accompanied by rolling trials on a laboratory rolling mill at the University of Duisburg-Essen, where a typical Round-OvalRound pass sequence was used for validation of the rolling model concerning lateral spread, inlet and outlet velocity as well as rolling force and torque calculation. The present paper shows how the material flow and the distribution of the velocity in the roll gap can be described. In subsequent rolling of bar and rod in a continuous rolling mill the dimensions can be influenced by application of longitudinal stresses and screwdown. The application of stress can be achieved by an inter-stand velocity mismatch. With the developed models the necessary velocity mismatch can be calculated.

Application of Velocity Analysis Picking for 2D Seismic Data Processing in West An-Najaf Are

In the current study, 2D seismic data in west An-Najaf (WN-36 line) were received after many steps of processing by Oil Exploration Company in 2018. Surface Consistent Amplitude Compensation (SCAC) was applied on the seismic data. The processing sequence in our study started by sorting data in a common mid-point (CMP) gather, in order to apply the velocity analysis using Interactive Velocity Analysis Application (INVA) with Omega system. Semblance of velocity was prepared to preform normal move-out (NMO) vs. Time. Accurate root mean square velocity (VRMS) was selected, which was controlled by flatness of the primary events. The resultant seismic velocity section for the study area shows that the velocity analysis became smother and provided an accurate seismic section.