MODERN DEVELOPMENTS IN SHALLOW SEISMIC REFRACTION TECHNIQUES

Geophysics ◽  
1962 ◽  
Vol 27 (2) ◽  
pp. 198-212 ◽  
Author(s):  
J. C. Stam
Keyword(s):  
Seismic Refraction ◽  
Seismic Surveys ◽  
Shallow Seismic ◽  
Engineering Problems ◽  
The One

A brief review is given of the development of seismic refraction equipment applicable to engineering problems. Specific aspects of the one‐channel and the multi‐channel equipments are compared and their relative usefulness discussed. Examples of some seismic surveys are presented.

Determination of depths to an irregular interface in shallow seismic refraction surveys using a pocket calculator

Geophysics ◽  
1979 ◽  
Vol 44 (12) ◽  
pp. 1987-1998 ◽  
Author(s):  
David Cummings
Keyword(s):  
Seismic Refraction ◽  
Residual Soil ◽  
Rapid Reduction ◽  
Seismic Surveys ◽  
Shallow Seismic ◽  
Bedrock Surface ◽  
Reducing Costs ◽  
Irregular Interface ◽  
Adequate Data

Engineering geologic problems commonly involve the determination of depth to bedrock where it is overlain by residual soil or dry and saturated alluvium. The buried bedrock surface is commonly irregular and the nature of such irregularities must be known, for example, in (1) foundation studies where irregularities on the bedrock surface could indicate faults, or (2) groundwater studies where low areas in the bedrock may indicate channels for groundwater flow which may be targets for drilling. Seismic refraction surveys have proven to be a simple and accurate means of providing adequate data for describing irregularities on the bedrock surface, especially when the data are analyzed by the “plus‐minus” method of the wavefront approach. The method can be programmed readily for a Hewlett‐Packard HP-45 hand calculator, enabling rapid reduction of the data in the field. On‐site data reduction and interpretation result in greater efficiency by allowing immediate recognition of those areas where more detailed information may be needed, thereby precluding repeat surveys and reducing costs. For this purpose, suitable computer programs for the two‐ and three‐layer cases are developed, as well as programs for elevation and weathered zone corrections commonly needed in such shallow seismic surveys.

Use Of Shallow Seismic Surveys In The Exploration Of Nearshore Placers Off Maharashtra Coast, India

1988 ◽  
Author(s):  
V.G. Rajamanickam ◽  
V.M. Ramanna ◽  
A.R. Gujar
Keyword(s):  
Seismic Surveys ◽  
Shallow Seismic

scholarly journals Delineation of Weathered Layer Using Uphole and Surface Seismic Refraction Methods in Parts of Niger Delta, Nigeria

2021 ◽  
Vol 26 (1) ◽  
pp. 58-66
Author(s):  
Mfoniso Aka ◽  
Okechukwu Agbasi
Keyword(s):  
Niger Delta ◽  
Average Velocity ◽  
Seismic Refraction ◽  
Low Velocity ◽  
Engineering Structures ◽  
Experimental Proof ◽  
Seismic Surveys ◽  
Shot Point ◽  
Weathered Layer ◽  
Velocity Zone

Uphole and surface seismic refraction surveys were carried out in parts of the Niger Delta, Nigeria, to delineate weathering thickness and velocity associated with aweathered layer. A total of twelve uphole and surface seismic refraction surveyswere shot, computed and analyzed. The velocity of the uphole seismic refraction ranged from 344.8 to 680.3 m/s with a thickness of 5.45 to 13.35 m. Surface seismic refraction ranged from 326.6 to 670.2 m/s and 4.30 to 12.0 m, respectively. The average velocity and thickness ranged from 559.6 to 548.0 m/s and 9.43 to 8.63m with differences of 11.6 m/s and 0.83 m respectively. The VW/VS ratios ranged from 0.955 to 1.059. This indicates that the uphole velocity is higher than the surface refraction velocity leading to low VW/VS values. This is a direct experimental proof of a low velocity zone, confirming the weathered nature of the area. The results of both refraction methods are reliable; the differences in surface refraction values are due to shot point offsets. Based on these findings, it is recommended that shots for seismic surveys should be located above 15.0 m in the area to delineate the effects associated with weathered layers to ensure that will be competent to withstand engineering structures.  

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