Geophysical Survey

About: Geophysical Survey is a facility organization based out in Obninsk, Russia. It is known for research contribution in the topics: Geology & Fault (geology). The organization has 308 authors who have published 256 publications receiving 3067 citations. The organization is also known as: Federal State Institution of Science Geophysical Survey of the Siberian Branch of the Russian Academy of Sciences.

Seismic hazard assessment for Adria

Abstract: The Adriatic region was chosen as one of the test areas in the GSHAP program and, consequently, its seismic hazard was computed. The standard hazard map chosen by GSHAP represents PGA with a 475-year return period. Some other parameters, as the spectral acceleration and the uniform hazard response spectra for the main Adriatic towns, have been computed for a better representation of the regional hazard. The most hazardous area remains identified in the Cephalonia zone, where strong earthquakes frequently occur. The Southern Apennines are characterised by a slightly lower hazard, while the Adriatic Sea itself, the Poplain and the Apulian peninsula are almost aseismic.

Determining the condition of a concrete structure using electromagnetic signals

Abstract: Ground penetrating radar (GPR) is a technique that may be used to image the inside of a structure by collecting the echoes (or reflections) resulting from electromagnetic signals such as, for example, electromagnetic waves of typically high frequency, being radiated into the structure. Typically, the rebars inside of a reinforced concrete structure are strong radar wave reflectors. Locating deteriorated areas within a reinforced concrete structure may be accomplished by analyzing the reflections, particularly the amplitudes of the reflections, from the rebars in the reinforced concrete structure. Furthermore, the extent of deterioration of these located areas may be determined from such analysis. Significantly, the system and method described herein, when applied to determine the extent of deterioration of one or more areas of a reinforced concrete bridge deck, is effective even if a layer of asphalt is laminated to the surface of the reinforced bridge deck. A method and system for determining a condition of a substantially concrete structure is provided. One or more computer-readable data signals is received, where each data signal represents an electromagnetic signal detected from an area of the concrete structure. One or more of the detected electromagnetic signals include electromagnetic energy reflected from the concrete structure as a result of an electromagnetic signal transmitted into the concrete structure. An extent of deterioration of one or more areas of the substantially concrete structure are determined from the one or more computer-readable data signals.

Prestack Kirchhoff depth migration of shallow seismic data

Abstract: Prestack Kirchhoff depth migration is applied successfully to shallow seismic data from a waste disposal site near Arnstadt in Thuringia, Germany. The motivation behind this study was to locate an underground building buried in a waste disposal. The processing sequence of the prestack migration is simplified significantly as compared to standard common (CMP) data processing. It includes only two parts: (1) velocity-depth-model estimation and (2) prestack depth migration. In contrast to conventional CMP stacking, prestack migration does not require a separation of reflections and refractions in the shot data. It still provides an appropriate image. Our data example shows that a superior image can be achieved that would contain not just subtle improvements but a qualitative step forward in resolution and signal-to-noise ratio.

Development of a time–frequency approach to quantify railroad ballast fouling condition using ultra-wide band ground-penetrating radar data

Abstract: This paper discusses the use of ground-penetrating radar (GPR) to assess railroad track substructure conditions. An ultra-wide band (UWB) GPR system, having a centre frequency at or higher than 2 GHz, can be used to detect the scattering pattern and to predict air void volume in railroad ballast. A time–frequency technique was implemented to characterise the signal in time and frequency domains simultaneously. Because electromagnetic energy attenuation is highly frequency dependent, the frequency sub-bands of the reflected UWB GPR signal can be analysed separately to quantify the fouling material and quantify moisture content. Additionally, to validate the GPR system capability, a ground truth field survey was conducted. Using ballast samples collected from the field for validation, this paper shows that a time–frequency analysis may provide a new method to measure the thickness of clean ballast, detect the trapped water and assess the ballast fouling and moisture content along the track.