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.

Preliminary applications of a land surface temperature retrieval method to IASI and AIRS data

Abstract: Land surface temperature LST is one of the key state variables for many applications. This article aims to apply our previously developed LST retrieval method to infrared atmospheric sounding interferometer IASI and atmospheric infrared sounder AIRS data. On the basis of the opposite characteristics of the atmospheric spectral absorption and surface spectral emissivity, a ‘downwelling radiance residual index’ DRRI has been recalled and improved to obtain LST and emissivity. To construct an efficient DRRI, an automatic channel selection procedure has been proposed, and 11 groups of channels have been selected within the range 800–1000 cm−1. The DRRI has been tested with IASI and AIRS data. For the IASI data, the radiosonde data have been used to correct for atmospheric effects and to retrieve LST, while the atmospheric profiles retrieved from AIRS data have been used to perform the atmospheric corrections and subsequently to estimate LST from AIRS data. The differences between IASI-and Moderate Resolution Imaging Spectroradiometer MODIS-derived LSTs are no more than 2 K, while the differences between AIRS-and MODIS-derived LSTs are less than 5 K. Even though an exceptionally problematic value occurred –12.89 K, the overall differences between AIRS-estimated LST and the AIRS L2 LST product are no more than 5 K. Although the IASI-derived LST is more accurate than the AIRS-derived one, the convenient retrieval of AIRS atmospheric profile made this method more applicable. Limitations and uncertainties in retrieving LST using the DRRI method are also discussed.

High-frequency seismic noise: Results of investigation in Kamchatka

Abstract: The investigation of seismic noise in Kamchatka is carried out for the control of the medium stress condition and search of the strong earthquakes precursors. The main directions of this research are modulation of high-frequency seismic noise (HFSN, frequency range of the first tens of Hz, amplitudes about 10−9–10−12 m) by the Earth tides and temporal variations of HFSN parameters connected with the strong earthquake preparation. For reception of the statistically significant characteristics of HFSN and tides connection it was necessary to carry out long-term HFSN observations in points free from anthropogenous influence as far as possible. The station of HFSN observation was organized in the settlement Nachiky. The sensor is a narrow-band (Q = 100) piezoelectric seismometer, tuned to frequency 30 Hz. Signal envelope is recorded and analyzed. The continuous HFSN registration was begun in 1990 and proceeds till now. In 2000 the second station was established in the complex geophysical observatory “Karymshina”. The HFSN sensor is set up in the borehole at the depth of 30 m. The research of HFSN structure gave the opportunity to allocate HFSN components connected with the Earth tides. Besides it was revealed that the tidal response is not stable in time: the intervals of the tidal component existence are replaced by intervals of its absence, correlation between tide and HFSN varies in time, while tides have constant parameters. We propose a hypothesis about the connection of variations of the tidal components in HFSN data with the tectonic conditions in region, and consequently, about an opportunity to use this phenomenon for the prediction of strong earthquakes. The phase of the HFSN component connected with a tidal wave O1 (T = 25.8 h) was chosen as a parameter. The choice of wave O1 is connected with its greatest hindrance-immunity. It was shown that the stabilization of this phase is observed before earthquakes with M > 6.0, occurred at distances up to 250 km from the HFSN registration point, within time from several weeks to several months. Since 1996 such an analysis of the HFSN response to tides is conducted in an operative mode, and only in 1 case out of 19 the large earthquake precursor was not shown in any way.

CRInSAR for landslide deformation monitoring: A case in threegorge area

Abstract: Landslide in threegorge area is a severe geohazard threatening many people. Conventional differential SAR interferometry (DInSAR) and Persistent Scatterers for SAR interferometry (PSInSAR) technique are unsuitable for landslide deformation monitoring in this area due to temporal and lack of natural phase stable point targets. The method of DInSAR using corner reflectors (CRInSAR) is a powerful tool in the vegetation area. The procedure of DInSAR using corner reflectors (CRInSAR) used by this paper is briefly introduced. Using ENVISAT ASAR time series data, the deformation of 12 corner reflectors (CR) in Shuping landslide are analyzed. As to the CR with slow creep deformation, the CRInSAR results are reliable. But as to the CR with nonlinear accelerated deformation, our CRInSAR method still needs to be enhanced.

Object Recognition of Ground Penetrating Radar in Karst Regions Using Wavelet Energy Spectral Analysis

Abstract: The frequency and amplitude characteristics derived from the Ground Penetrating Radar (GPR) data have been widely applied to object recognition in karst areas, but still meet some limitations. Here we present a new method using wavelet energy spectral analysis. First we analyze the GPR signals of typical samples in karst areas and obtain their wavelet energy spectra, which consist of the energy eigenvectors on different scales and frequency bands. Then the object recognition is achieved by comparing the characteristic energy spectra with those of studied object. Both the data analysis and experiments demonstrate that the wavelet energy spectrum can directly show characteristics of object signals, which is very effective for the object recognition in karst regions from the GPR survey.

Contouring gravity anomaly maps by digital plotter

Abstract: Contouring gravity anomalies by digital plotter given values at points on a square grid is achieved by two-way polynomial interpolation so that the interpolated values fit exactly at the grid points. Contours are drawn for one grid square at a time using the 2n × 2n array of grid values surrounding the square. The method of polynomial interpolation is designed to ensure continuity in the gradients of the contours across the boundaries of each square.