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Influence of ghost reflection interface on seismic shooting effect and its application
虚反射界面对地震激发效果的影响及其应用

WANG Yong-Zhuo,DU Gui-Feng,FU Zhao-Kui,Zhou Zhi-Cai,Yu Chun-Ling,
王永卓
,杜桂锋,傅朝奎,周志才,于春玲

地球物理学进展 , 2009,
Abstract: In the process of seismic data acquisition, surface ghost reflection interface will have great influence on the shooting effect of seismic wave; while in the meantime, it is also an important factor for determining the shooting depth of dynamite focus. In this paper, the method for determining the distance between dynamite focus to ghost reflection interface is discussed, and the influence of ghost reflection interface on seismic shooting is analyzed, demonstrating how to select the optimum well depth to minimized various secondary interference caused by focus, obtain relatively good seismic shooting wavelets and collect ideal seismic data.
High resolution reflection seismic profiling over the Tjellefonna fault in the M re-Tr ndelag Fault Complex, Norway
E. Lundberg, C. Juhlin,A. Nasuti
Solid Earth (SE) & Discussions (SED) , 2012, DOI: 10.5194/se-3-175-2012
Abstract: The M re-Tr ndelag Fault Complex (MTFC) is one of the most prominent fault zones of Norway, both onshore and offshore. In spite of its importance, very little is known of the deeper structure of the individual fault segments comprising the fault complex. Most seismic lines have been recorded offshore or focused on deeper structures. This paper presents results from two reflection seismic profiles, located on each side of the Tingvollfjord, acquired over the Tjellefonna fault in the southeastern part of the MTFC. Possible kilometer scale vertical offsets, reflecting large scale northwest-dipping normal faulting, separating the high topography to the southeast from lower topography to the northwest have been proposed for the Tjellefonna fault or the Baeverdalen lineament. In this study, however, the Tjellefonna fault is interpreted to dip approximately 50–60° towards the southeast to depths of at least 1.3 km. Travel-time modeling of reflections associated with the fault was used to establish the geometry of the fault structure at depth, while detailed analysis of first P-wave arrivals in shot gathers, together with resistivity profiles, were used to define the near surface geometry of the fault zone. A continuation of the structure on the northeastern side of the Tingvollfjord is suggested by correlation of an in strike direction P-S converted reflection (generated by a fracture zone) seen on the reflection data from that side of the Tingvollfjord. The reflection seismic data correlate well with resistivity profiles and recently published near surface geophysical data. A highly reflective package forming a gentle antiform structure was also identified on both seismic profiles. This structure could be related to the folded amphibolite lenses seen on the surface or possibly by an important boundary within the gneissic basement rocks of the Western Gneiss Region. The fold hinge line of the structure is parallel with the Tjellefonna fault trace suggesting that the folding and faulting may have been related.
High resolution reflection seismic profiling over the Tjellefonna fault in the M re-Tr ndelag Fault Complex, Norway  [PDF]
E. Lundberg,C. Juhlin,A. Nasuti
Solid Earth Discussions , 2012, DOI: 10.5194/sed-4-241-2012
Abstract: The M re-Tr ndelag Fault Complex (MTFC) is one of the most prominent fault zones of Norway, both onshore and offshore. In spite of its importance, very little is known of the deeper structure of the individual fault segments comprising the fault complex. Most seismic lines have been recorded offshore or focused on deeper structures. This paper presents results from two reflection seismic profiles, located on each side of the Tingvollfjord, acquired over the Tjellefonna fault in the south-eastern part of the MTFC. Possible kilometer scale vertical offsets reflecting, large scale north-west dipping normal faulting separating the high topography to the south-east from lower topography to the north-west have been proposed for the Tjellefonna fault. In this study, however, the Tjellefonna fault is interpreted to dip approximately 50–60° towards the south-east to depths of at least 1.4 km. Travel-time modeling of reflections associated with the fault was used to establish the geometry of the fault structure at depth and detailed analysis of first P-wave arrivals in shot-gathers together with resistivity profiles were used to define the near surface geometry of the fault zone. A continuation of the structure on the north-eastern side of the Tingvollfjord is suggested by correlation of an in strike direction P-S converted reflection (generated by a fracture zone) seen on the reflection data from that side of the Tingvollfjord. The reflection seismic data correlate well with resistivity profiles and recently published near surface geophysical data. A highly reflective package forming a gentle antiform structure was also identified on both seismic profiles. The structure may be an important boundary within the gneissic basement rocks of the Western Gneiss Region. The Fold Hinge Line is parallel with the Tjellefonna fault trace while the topographic lineament diverges, following secondary fracture zones towards north-east.
Joint inversion of magnetotelluric and seismic data based on random resistivity and velocity distributions
电阻率和速度随机分布的MT与地震联合反演

YU Peng,DAI Ming-Gang,WANG Jia-Lin,WU Jian-Sheng,
于鹏

地球物理学报 , 2009,
Abstract: On the basis of existing research results, we develop a model construction method based on common gridded model with random resistivity and velocity distributions to meet the needs of joint inversion and the complicated model with large variations of physical properties. The forward modelings for magnetotelluric (MT) field using finite element method and the seismic travel-time computing using improved ray-tracing method, are both suitable based on this kind of unified gridded media with random resistivity and velocity distributions. Incorporating with the improved very fast simulated annealing algorithm, we fulfill the synchronous joint inversion of MT & seismic data based on this kind of common gridded model. The test of the complicated model with uneven terrain and uncommon interface and large variations of resistivity and velocity, shows the effects of joint inversion in accurately determining the resistivity and velocity structures. It improves the limitation of former studies confined in simple models of joint inversion. Moreover, the joint inversion of the observed data in an area with low-quality surveyed seismic data, proves it is practicable in improving inversion accuracy with constrained prior information.
Multiresolution analysis applied to interpretation of seismic reflection data  [PDF]
D. E. Rivera-Recillas,M. M. Lozada-Zumaeta,G. Ronquillo-Jarillo,J. O. Campos-Enríquez
Geofísica internacional , 2005,
Abstract: We have developed a method of seismic multiresolution analysis based on the discrete wavelet transform. We illustrate the potential use in petroleum exploration of the joint application of multiresolution analysis and seismic attributes for a real case study. Three major reflections at the base of the seismic window are associated with oil-bearing Lower Cretaceous geologic formations. These major reflections seem to be continued towards the left by less clear and lower amplitude reflections. On the strength of multiresolution analysis from the seismic data or from envelope amplitude, instantaneous phase and frequency could not be discarded, the possible continuations as a stratigraphic continuation was suggested in both data sets. Improved resolution at different scales provided by multiresolution analysis of the seismic attributes enabled a finer analysis, and continuity was no longer fully supported. It was possible to distinguish the high amplitude continuous reflections from their continuations. Higher resolution improved discrimination. The joint use of multiresolution and seismic attributes has potential applications in the field of seismic reflection. We use successfully the discrete wavelet transform as an alternative to the continuous wavelet transform.
Electrical resistivity imaging of a seismic region in northern Baja California, Mexico
Carpio, Ricardo Antonio;Romo, José Manuel;Frez, José;Gómez-Trevi?o, Enrique;Suárez-Vidal, Francisco;
Geofísica internacional , 2011,
Abstract: magnetotelluric (mt) observations collected at 17 sites along a 45-km profile were used to investigate the electrical conductivity structure in the ojos negros seismic zone, in northern baja california, mexico. in this region, seismic activity registered by a local network consists mainly of micro-earthquakes that occur at depths between 13 to 15 km. epicenters mapped at the surface show that seismic activity is not aligned with known faults but is scattered over the ojos negros valley. we interpret the mt data using 2-d inversion codes applied to series and parallel invariant responses, and also to traditional groom-bailey's te and tm responses. the resistivity models obtained for both approaches are similar. the models reveal a high conductivity anomaly closely correlated with the distribution of hypocenters at depth. most of the seismic events cluster in a zone of maximum resistivity gradient located at the rim of the high-conductive anomaly. the shape of the conductivity anomaly and the spatial attitude of the seismic events suggest that ojos negros fault is a major listric structure accommodating normal and dextral strike-slip movement. the large resistivity contrast across the fault-plane is probably related to a compositional contrast between metamorphic rocks in the footwall and plutonic rocks in the hanging wall of the fault. the fault-plane at depth seems to separate ductile, highly conductive metamorphic rocks from more brittle, mid-resistivity shattered granitic rocks. the mt resistivity model and the earthquake data together yield an explanation that either technique could not provide alone, throwing light on the physical conditions of the rocks in the middle crust.
Reflection Symmetry and Quantized Hall Resistivity near Quantum Hall Transition  [PDF]
D. N. Sheng,Z. Y. Weng
Physics , 1998, DOI: 10.1103/PhysRevB.59.R7821
Abstract: We present a direct numerical evidence for reflection symmetry of longitudinal resistivity $\rho_{xx}$ and quantized Hall resistivity $\rho_{xy}$ near the transition between $\nu=1$ quantum Hall state and insulator, in accord with the recent experiments. Our results show that a universal scaling behavior of conductances, $\sigma_{xx}$ and $\sigma_{xy}$, in the transition regime decide the reflection symmetry of $\rho_{xx}$ and quantization of $\rho_{xy}$, independent of particle-hole symmetry. We also find that in insulating phase away from the transition region $\rho_{xy}$ deviates from the quantization and diverges with $\rho_{xx}$.
Merge-Optimization Method of Combined Tomography of Seismic Refraction and Resistivity Data  [PDF]
Andy A. Bery
ISRN Geophysics , 2012, DOI: 10.5402/2012/293132
Abstract: This paper discussed a novel application called merge-optimization method that combines resistivity and seismic refraction data to provide a detailed knowledge of the studied site. This method is interesting because it is able to show strong accuracy of two geophysical imaging methods based on many of data points collected from the conducted geophysical surveys of disparate data sets based strictly on geophysical models as an aid for model integration for two-dimensional environments. The geophysical methods used are high resolution methods. The resistivity imaging used in this survey is able to resolve the subsurface condition of the studied site with low RMS error (less than 2.0%) and 0.5 metre electrodes interval. For seismic refraction method, high resolution of seismic is used for correlation with resistivity results. Geophones spacing is 1.0 metre and the total number of shot-points is 15, which provides very dense data point. The algorithms of merge-optimization have been applied to two data sets collected at the studied site. The resulting images have been proven to be successful because they satisfy the data and are geometrically similar. The regression coefficient found for conductivity-resistivity correlation is 95.2%. 1. Introduction The characterization of the subsurface requires a detailed knowledge of several properties of the composing rocks and fluids. Whereas some of these properties can be measured directly (seismic and borehole methods), other properties have to be estimated by indirect measurement methods such as resistivity, TEM, and magnetic. However, it is not uncommon that the geophysical data yield models of limited accuracy which may not contribute significantly to our understanding of the subsurface condition or may show incompatibilities. Thus, a new technique needs to be produced not only for better interpretation by geophysics but also for nongeophysical background people such as engineers and architects. The distribution of uncorrelated physical properties seems to be controlled by common subsurface attributes, when taken into account, able to improve and resolve the accuracy of the geophysical imaging results. An outstanding feature of the subsurface that is common to the geophysical data is the geometrical distribution of the physical properties which can be measured by the physical property changes. This condition of commonality can be incorporated in the process of estimation to obtain meaningful and more reliable subsurface imaging results. 2. Methodology for Merge-Optimization Method In this paper, seismic
Modeling the Specific Seismic Risk Considering the Weight of Determining Variables
Liber Galbán Rodriguez, Elio Quiala Ortiz
Open Access Library Journal (OALib Journal) , 2015, DOI: 10.4236/oalib.1101157
Abstract: The seismic risk determination for any country is a vital tool in the process of physical planning, construction and reduction of disasters caused by earthquakes. In recent years, there have been several studies on the subject, however, different methodologies could be improved from the design of a set of basic criteria, which using the advantages of Geographic Information Systems (GIS), could help to establish greater clarity in the seismic risk determining. To meet this goal, in this study, the authors propose a new allocation methodology based on levels of importance of variables that influence the specific seismic risk assessment and propose a new formula for mathematical determination through modeling with GIS.
Integrated interpretation of seismic and resistivity images across the Val d'Agri graben (Italy)
S. Morandi,E. Ceragioli
Annals of Geophysics , 2002, DOI: 10.4401/ag-3510
Abstract: Val d'Agri is a recent SSW - NNE graben located in the middle of the Southern Apennines thrust belt chain and emplaced in Plio-Pleistocene.The recent sedimentation of the valley represents a local critical geophysical problem. Several strong near surface velocity anomalies and scattering degrades seismic data in different ways and compromises the seismic visibility. In 1998, ENI and Enterprise, with the contribution of the European Community (ESIT R & D project - Enhance Seismic In Thrust Belt; EU Thermie fund) acquired two experimental seismic and Resistivity lines across the valley. The purpose of the project was to look for methods able to enhance seismic data quality and optimize the data processing flow for thrust belt areas. During the work, it was clear that some part of the seismic data processing flow could be used for the detailed geological interpretation of the near subsurface too. In fact, the integrated interpretation of the near surface tomography velocity/depth seismic section, built for enhancing the resolution of static corrections, with the HR resistivity profile, acquired for enhancing the seismic source coupling, allowed a quite detailed lithological interpretation of the main shallow velocity changes and the 2D reconstruction of the structural setting of the valley.
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