Geophysical Survey

About: Geophysical Survey is a facility organization based out in Obninsk, Russia. It is known for research contribution in the topics: Geology & Seismology. 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.

Signature of remnant slabs in the North Pacific from P‐wave tomography

Abstract: SUMMARY A 3-D ray-tracing technique was used in a global tomographic inversion in order to obtaintomographicimagesoftheNorthPacific.ThedatareportedbytheGeophysical SurveyofRussia(1955‐1997)wereusedtogetherwiththecataloguesoftheInternational SeismologicalCenter(1964‐1991)andtheUSGeologicalSurveyNationalEarthquake Information Center (1991‐1998), and the recompiled catalogue was reprocessed. The final data set, used for following the inversion, contained 523430 summary ray paths. The whole of the Earth’s mantle was parametrized by cells of 2°◊2° and 19 layers. The large and sparse system of observation equations was solved using an iterative LSQR algorithm. Asubhorizontalhigh-velocityanomalyisrevealedjustabovethe660kmdiscontinuity beneaththeAleutiansubductionzone.Thishigh-velocityfeatureisobservedatlatitudes of up to~70°N and is interpreted as a remnant of the subducted Kula plate, which disappeared through ridge subduction at about 48Ma. A further positive velocity perturbation feature can be identified beneath the Chukotka peninsula and Okhotsk Sea, extending from~300 to~660km depth and then either extending further down to~800km (Chukotka) or deflecting along the 660km discontinuity (Okhotsk Sea). This high-velocity anomaly is interpreted as a remnant slab of the Okhotsk plate accreted to Siberia at~55Ma.

Geophysical surveying system employing electromagnetic impulses

Abstract: A geophysical survey system is disclosed for determining the character of the subterrain by analysis of reflections from electromagnetic pulses radiated into the ground. The system repetitively radiates into the ground a short duration electromagnetic pulse having a rise time in the order of 1 nanosecond. The antenna which radiates the pulse into the ground is employed to receive the reflections of the pulse. The received signals are coupled through a transmit-receive network to a receiver which permits the input signal waveform to be reconstructed from a sequence of samples taken by the receiver. The system is capable of generating a profile chart indicating the magnitudes of the reflected signals and the depths at which the reflections occurred.

The Seismotectonic Characteristics of Slovenia

Abstract: Slovenia with its neighbouring areas lies at the junction of the Alps, the Dinarides and the Pannonian basin. These belong to the three plates: Europe, Adria and Tisza. On the Slovenian territory itself converge the External Dinarides NW-SE oriented right lateral strike-slip faults, the Transdanubian Range NE-SW oriented left lateral strike-slip faults, and the Southern Alps E-W oriented thrusts. The direction of the principal stress σ1, (azimuth = 6°, dip = 8°) is determined under the assumption of uniform stress throughout the region. Dip of the least principal stress σ3 of 5° is consistent with the regional strike-slip regime. Listed structures form a pure shear structural mechanism on a regional scale.

Scattering analysis of ground-penetrating radar data to quantify railroad ballast contamination

Abstract: This paper will evaluate ground-penetrating radar (GPR) as a non-destructive method to rapidly, effectively, and continually assess the conditions of railroad ballast. Compared to uniformly graded, clean ballast, fouled ballast has a finer, well-graded particle size with fewer air voids. Ballast under different conditions generates various GPR electromagnetic scattering patterns. A field GPR survey with multiple sets of 1 and 2 GHz air-horn antennae was conducted in summer 2005 at the Transportation Technology Center, Inc. (TTCI) in Pueblo, Colorado. The 2 GHz antenna was found to be more sensitive to the change in scattering pattern. Appropriate data processing was used to remove the effects of the rails to obtain clear GPR images of the subsurface layers. From the image analysis, ballast thickness, ballast fouling condition, and trapped water can be assessed.