ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01984.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTThis paper gives an interpretation of a specific type of refracted‐diffracted waves. The solution is supported by the good accord of data in seismic and magnetic interpretation. Beyond solving the problem of the phenomenon, the interpretation of such events shows that in the exploration of dykes and intruded formations the refracted‐diffracted waves can—under favourable conditions—also render some useful info

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01985.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTIn designing as well as in the construction of hydro‐electric power plants and water‐supply projects in karst, the knowledge of the location of groundwater flows is invaluable. Attempts made so far in this direction have not produced the desired results and all the methods known so far have shown to be more or less ineffective, especially with respect to deep‐seated underground flows.An interesting suggestion on the possible determination of the groundwater flow location by using a specific geophysical prospecting procedure is based on the studies and knowledge of groundwater flows in the karstland of Yugoslavia. The procedure is as follows: a time‐bomb thrown down a swallow‐hole travels down to the groundwater flow and explodes at a predetermined moment. Elastic waves generated by the explosion propagate reaching the surface, where they are detected by properly arranged geophones that are connected with a standard seismic apparatus. By a specific graphical or arithmetical method the coordinates of the epicentre and hypocentre of the underground explosion can be worked out, and thus the location of the groundwater flow determined. By successive repetition of the experiment, i.e. by different time activation of underground explosion of the time‐bomb, the location of the groundwater flow can be defined over longer paths.The success of the experiment depends upon a number of factors all of which must be met. If only one of them is overlooked, the experiment will not succeed. All this calls for great care both in preliminary work and in the course of the experiment. Substantial funds invested in and considerable time required in executing the experiment are multiply recompensed by the success of the experiment. The information obtained about the location of groundwater flows will directly affect the maximum operating pool adopted for hydro‐electric power projects and the most favourable point in cutting off groundwater flows and bringing them to the surface for water‐

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01986.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTStudies made on head waves in a large number of two‐dimensional horizontal and inclined layer seismic models are described. The assumption that the amplitude of head wave decreases exponentially with distance is found to be valid in horizontal layers. For the correct estimation of the head wave decay coefficient, the decrease of amplitude due to the divergence of wave energy should always be considered.The variations of head wave amplitude at large distances from the source appear to follow the theory of Heelan (1953). It is, however, concluded that the theory can only be verified from the measurements in models which have large velocity contrast and thick layer at the top.A prominent interference phenomenon between the direct and head wave has been observed near the critical distance. This is more marked for up‐dip profile in the case of inclined layer models. The rate of head wave amplitude decrease with distance beyond the zone of interference is found to depend on dip angle, direction of the dip, and velocity contr

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01987.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTVelocity Spectra which were originally developed for the optimum stacking of seismic data have been found to give considerable information concerning lithologic and stratigraphic changes in the geologic section. In the Gulf of Mexico shale sections and sand bodies have been recognized on the Velocity Spectra display, and in the Caribbean last year a first attempt was made to utilize Velocity Spectra information for the determination and mapping of lithology. Since that time, a new program has been developed which takes dip into account when computing the interval velocity. This program has been applied to a seismic section in the North Sea which has resulted in a geologic model derived from interval velocities which were found to be quite consistent. Such a model can be of great value in geological interpretation.

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01988.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractResistivity surveys including surface measurements and electric well logging are at present carried out as routine techniques by a Groundwater Project of the United Nations Special Fund in arid valleys of the Argentine eastern Andes.The aims of the Project are the evaluation of ground water supplies in 5 pilot areas and the training of Argentine professionals in modern techniques of groundwater investigation.In Zonda and Tulüm Valleys, one of the five pilot areas, the groundwater body is essentially represented by alluvium of San Juan River and upper Tertiary gravels lying upon impervious clayey Tertiary sediments.Profiles of electrical soundings—spread in the valleys normal to the structural trends—were completed as a broad reconnaissance type investigation. In the outwash plain, a thick clayey overburden sometimes covered by saline material produces a masking effect on the deep sands and gravels and makes the evaluation of true resistivities difficult. Under certain conditions, appropriate use of electric well logging results helps solving the ambiguities found in the interpretation of the electrical soundings. Two examples are discussed.Also a typical development of surface resistivity interpretation as a whole is presented. Emphasis is placed upon the significance of the transverse resistance values to better interpret the hydrogeological picture. The last stage in data processing, presented on a map of the resistive fill and the conductive basement, provides evidence of the strong structural control of the valleys and shows the main variations in the ground water body constitu

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01989.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTDuring the years from 1965 until 1967, a German/Afghan team carried out a number of geoelectrical resistivity measurements according to the “Four‐Point‐Method” within the framework of Technical Assistance to Afghanistan.On two selected objects of investigation, i.e. Kabul (69°10 E, 34°30′N) and Zarkašan (67°40′E, 32° 54.5′N), the possibilities and limits of the resistivity method in the exploration of useful groundwater resources, of the geological structure, and in the treatment of problems pertaining to mineral deposits in Afghanistan are demonstrated. In connection with geological mapping these geophysical investigations provided certain conceptions on the structure and the stratigraphy of the intramontane basins in the region south of the Hindukush mountains. Field interpretations are checked by boreholes and by com

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01990.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTThis paper deals with electromagnetic fields in the so called “Transient Induced Polarization Technique”. Field equations are integrated in the case of a polarizable sphere inbedded in a sterile overburden. The existence of a remanent polarization vector P which slowly decays once the charging current has been cut off is taken as the initial condition. When the surface between the air and overburden is (as a first step) disregarded, the Laplace transform of the EM fields is given. The integral of the electric field (which is fairly often the result of prospection work) is independent of the various time constants related to electrochemical processes, but it stands as a good measurement of the total electrostatic dipole created by the charging current.We investigate the geometrical circumstances that can bring negative values of I.P. signal. Such negative values can be found in two cases: 1. The discharge currents are. distorted by the ground surface. 2. The I.P. signal is picked up by electrodes inside the polarizable material.The last part is dedicated to an account of experimental work performed on models and of an actual case history.The mathematical derivations are included in an appen

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01991.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

摘要:

ABSTRACTRecordings were made with three types of detector of the primary compressional (P) and shear (S) wave pulses generated by explosions in boreholes. Charge weights varied from 0.08 kg to 9.5 kg and detector distances varied from about 3 m to about 80 m. Scaling by the simple factorW1/3whereWis the charge weight, enabled observations from different sized charges to be fitted to a single expression.Experiments were carried out in the Bunter sandstone and the London clay and both fluid and solid tamping were used. This variation in tamping had no significant effect on the P‐waves but it may have affected the generation of SV‐waves. In both media the P‐wave energy carried at 30 m from the shot by frequencies less than 100 Hz decreased rapidly with depth and was usually 1–2 % of the available chemical energy for a shot depth of 15 m. The S‐wave energy was much less than this, but was highly directional.The P‐wave pulse had the appearance of a damped sinusoid in very good agreement with the predictions of the ‘equivalent radiator’ hypothesis. However, the surface of this radiator should be identified not with the blown cavity but with the surface at which the tensile stresses associated with the stress wave become less than the tensile strength of the rock.The predominant frequency for a 1 kg charge at a depth of 15 m was 24 Hz in the clay and 52 Hz in the sandstone. In these and similar media, therefore, an effort should be made to keep individual charges less than 1 kg in reflection shooting and less than 10 kg in refraction shooting.The value ofQwas about 50 in clay and about 25 in the sandstone. These estimates are rather uncertain because of the small distances over which the pulses were observed.TheZ‐transforms of the sampled pulses indicated that they were all of minimum phase, o

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01992.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY

ISSN:0016-8025    

DOI:10.1111/j.1365-2478.1969.tb01993.x

出版商:Blackwell Publishing Ltd    

年代:1969

数据来源: WILEY