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.

Techniques of UAV system land use changes detection application

Abstract: The unmanned aerial vehicle( UAV) was able to acquire remote sensing images with low cost, precise and high spatial resolution information needed by management of Land use at desired time. The aim of this paper was to present an overview of the ongoing research on the potential and techniques of low-altitude UAV system for land use applications. The development of crucial subsystems consisting of the UAV platforms, multiple camera system, camera calibration and photogrammetric production, was introduced together. A procedure of images acquisition and photogrammetric processing was proposed. To detect land use changes, methods based on DSMs and DLG were discussed and adopted in this paper. Finally, analysis of land use research based UAVs was realized on real flight experiments of two study areas. The results of this study show that UAVs can be used successfully for land use change detection.

Correlation Fractal and Multifractal Characteristics of Seismic Activity in the Taiwan Area, China

Abstract: Based on the analysis of newly collected data of plate tectonics, distribution of active faults and crustal deformation, the Taiwan area is divided into two seismic regions and six seismic belts. Then, correlation fractal dimensions of all the regions and belts are calculated, and the fractal characteristics of hypocenteral distribution can be quantitatively analyzed. Finally, multifractal dimensions Dq and f(α) are calculated by using the earthquake catalog of the past 11 years in the Taiwan area. This study indicates that (1) there exists a favorable corresponding relationship between spatial images of seismic activity described with correlation fractal dimension analysis and tectonic settings; (2) the temporal structure of earthquakes is not single but multifractal fractal, and the pattern of Dq variation with time is a good indicator for predicting strong earthquake events.

Prestack migration velocity analysis based on simplified two-parameter moveout equation

Abstract: Stacking velocity VC2, vertical velocity ratio γ0, effective velocity ratio γeff, and anisotropic parameter χeff are correlated in the PS-converted-wave (PS-wave) anisotropic prestack Kirchhoff time migration (PKTM) velocity model and are thus difficult to independently determine. We extended the simplified two-parameter (stacking velocity VC2 and anisotropic parameter keff) moveout equation from stacking velocity analysis to PKTM velocity model updating and formed a new four-parameter (stacking velocity VC2, vertical velocity ratio γ0, effective velocity ratio γeff, and anisotropic parameter keff) PS-wave anisotropic PKTM velocity model updating and process flow based on the simplified two-parameter moveout equation. In the proposed method, first, the PS-wave two-parameter stacking velocity is analyzed to obtain the anisotropic PKTM initial velocity and anisotropic parameters; then, the velocity and anisotropic parameters are corrected by analyzing the residual moveout on common imaging point gathers after prestack time migration. The vertical velocity ratio γ0 of the prestack time migration velocity model is obtained with an appropriate method utilizing the P- and PS-wave stacked sections after level calibration. The initial effective velocity ratio γeff is calculated using the Thomsen (1999) equation in combination with the P-wave velocity analysis; ultimately, the final velocity model of the effective velocity ratio γeff is obtained by percentage scanning migration. This method simplifies the PS-wave parameter estimation in high-quality imaging, reduces the uncertainty of multiparameter estimations, and obtains good imaging results in practice.

The coastline remote sensing survey for Zhao Shu Island in Xisha Islands based on WorldView-2

Abstract: Due to diastrophism, tide action and human activities, the coastline is always in flux. There are lots of coral islands in the south sea of China. Remote sensing survey for the coastline not only can reassert the necessity and importance of coral protection, but also can provide basic data and scientific basis for island ecologic protection, reasonable utilization of land resources. The study area named Zhao Shu Island lies in Jintong Islands of Xisha. It is a coral island which has people inhabited. Using WorldView-2 satellite remote sensing images as data sources we carry out three phases of coastline investigation and monitoring. The satellite data phases are 2002, 2010 and 2013. Firstly, affirm the bands valuable for color composition on the basis of spectral and correlation analysis. Then extract the coastline by a series of image process, such as image correction, fusion, waterline extraction and coastline revision. Finally determine the coastline types and length by artificial interpretation. The results show that the island length is gradually smaller, which means the island area is reducing. The beach bedrock coast in northern island was eroded seriously especially during the period between 2010 and 2013. In addition, the shoal head shape in the western island changed a lot.

CO2 Monitoring by Using VSP-FWI-Synthetic Study on CO2-saturation and pressure-buildup differentiation

Abstract: Synthetic study on CO2-saturation and pressure-buildup differentiation by using VSP-FWI is conducted in a virtual CCS site. Geophysical and Reservoir simulation works are first implemented to create geophysical models before and after CO2 injection. Virtual VSP-FWI monitoring experiment is then implemented on the models. In parallel with this, simple linear equations to estimate CO2-saturation and pressure-buildup are derived. Inverted P- and S-wave velocities through the VSP-FWI are found to be highly accurate, and used in the derived equation. As a result the saturation change and reduction of differential pressure are estimated consistently with the values after reservoir simulation. This result indicates that CO2-saturation and pressure-buildup can be differentiated around the well, if both P- and S-wave velocities are accurately inferred by applying VSP-FWI and relevant rock-physics model is known.