A vertical array method for shallow seismic refraction surveying of the sea floor

Geophysics ◽  
1990 ◽  
Vol 55 (1) ◽  
pp. 92-96 ◽  
Author(s):  
J. A. Hunter ◽  
S. E. Pullan
Keyword(s):  
Seismic Refraction ◽  
Research Interest ◽  
Seismic Velocities ◽  
Vertical Array ◽  
Sea Floor ◽  
Site Investigations ◽  
Shallow Seismic ◽  
Continental Shelves ◽  
Defense Research ◽  
Research Studies

In recent years, specific requirements of offshore geotechnical site investigations, as well as detailed defense research studies, have stimulated research interest in methods for measuring seismic velocities of sea‐floor sediments on the continental shelves. Investigations have used wide‐angie subbottom reflection measurements (McKay and McKay, 1982), bottom‐laid refraction cables (Hunter et al., 1979), and towed refraction arrays, both on the surface (Hunter and Hobson, 1974) and at depth (Fortin et al., 1987; Fagot, 1983).

Experience with the generalized reciprocal method of seismic refraction interpretation for shallow engineering site investigation

Geophysics ◽  
1986 ◽  
Vol 51 (2) ◽  
pp. 255-265 ◽  
Author(s):  
P. J. Hatherly ◽  
M. J. Neville
Keyword(s):  
Seismic Refraction ◽  
Site Investigation ◽  
Complex Environments ◽  
Site Investigations ◽  
Shallow Seismic ◽  
South Wales ◽  
Refraction Method ◽  
Close Cooperation ◽  
Processing Techniques ◽  
Reciprocal Method

The shallow seismic refraction method has been used routinely during the initial investigation at many dam sites in New South Wales. By using computer processing techniques and advanced interpretational features of the generalized reciprocal method, it has been possible to derive a picture of the subsurface layering from the refraction results even in geologically complex environments. Close cooperation between the geophysicist and geologist is necessary to ensure proper use of the seismic results. The results may be used to guide subsequent drilling programs and to aid design and construction. This approach to engineering site investigations is demonstrated with results from two recent investigations.

scholarly journals Engineering Site Investigations using Surface Seismic Refraction Technique

2021 ◽  
Vol 655 (1) ◽  
pp. 012098
Author(s):  
O. O. Adewoyin ◽  
E.O. Joshua ◽  
M. L. Akinyemi ◽  
M. Omeje ◽  
T.A. Adagunodo ◽  
...  
Keyword(s):  
Seismic Refraction ◽  
Site Investigations

Thermal regime of the lithosphere in the Canadian ShieldThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (4) ◽  
pp. 389-408 ◽  
Author(s):  
Claire Perry ◽  
Carmen Rosieanu ◽  
Jean-Claude Mareschal ◽  
Claude Jaupart
Keyword(s):  
Heat Flow ◽  
Heat Generation ◽  
Seismic Refraction ◽  
Surface Heat ◽  
Canadian Shield ◽  
P Wave ◽  
Seismic Velocities ◽  
Flow Measurements ◽  
Surface Heat Flow ◽  
Mantle Heat Flow

Geothermal studies were conducted within the framework of Lithoprobe to systematically document variations of heat flow and surface heat production in the major geological provinces of the Canadian Shield. One of the main conclusions is that in the Shield the variations in surface heat flow are dominated by the crustal heat generation. Horizontal variations in mantle heat flow are too small to be resolved by heat flow measurements. Different methods constrain the mantle heat flow to be in the range of 12–18 mW·m–2. Most of the heat flow anomalies (high and low) are due to variations in crustal composition and structure. The vertical distribution of radioelements is characterized by a differentiation index (DI) that measures the ratio of the surface to the average crustal heat generation in a province. Determination of mantle temperatures requires the knowledge of both the surface heat flow and DI. Mantle temperatures increase with an increase in surface heat flow but decrease with an increase in DI. Stabilization of the crust is achieved by crustal differentiation that results in decreasing temperatures in the lower crust. Present mantle temperatures inferred from xenolith studies and variations in mantle seismic P-wave velocity (Pn) from seismic refraction surveys are consistent with geotherms calculated from heat flow. These results emphasize that deep lithospheric temperatures do not always increase with an increase in the surface heat flow. The dense data coverage that has been achieved in the Canadian Shield allows some discrimination between temperature and composition effects on seismic velocities in the lithospheric mantle.

A Measurement of Seismic Anistropy in the Northeast Pacific

1971 ◽  
Vol 8 (9) ◽  
pp. 1056-1064 ◽  
Author(s):  
C. E. Keen ◽  
D. L. Barrett
Keyword(s):  
Seismic Refraction ◽  
Maximum Velocity ◽  
Mean Value ◽  
Ocean Basin ◽  
P Wave ◽  
Sea Floor ◽  
P Wave Velocity ◽  
The Pacific ◽  
Magnetic Lineations ◽  
Sea Floor Spreading

A seismic refraction experiment was conducted in the Pacific Ocean basin, off the coast of British Columbia, Canada. The purpose of these measurements was to obtain an estimate of the anisotropy of the mantle P-wave velocity in the area and to relate this parameter to the direction of sea floor spreading. The results show that the crustal structure is similar to that measured elsewhere in the Pacific basin. Significant anisotropy of the mantle rocks is observed; the direction in which the maximum velocity occurs being 107° and the change of velocity, about 8% of the mean value, 8.07 km/s. The direction of maximum velocity does not coincide exactly with the direction of sea floor spreading, 090°, inferred from magnetic lineations.

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