scholarly journals Field comparison of shallow seismic sources near Chino, California

Geophysics ◽  
1992 ◽  
Vol 57 (5) ◽  
pp. 693-709 ◽  
Author(s):  
Richard D. Miller ◽  
Susan E. Pullan ◽  
Don W. Steeples ◽  
James A. Hunter
Keyword(s):  
Water Table ◽  
Seismic Source ◽  
Test Site ◽  
Single Site ◽  
Seismic Sources ◽  
Near Surface ◽  
Shallow Seismic ◽  
Site Characteristics ◽  
Weight Drop ◽  
Different Sources

Data from a shallow seismic‐source comparison test conducted in an area with a water‐table depth in excess of 30 m and near‐surface velocities less than 330 m/s were acquired from 13 different sources at a single site near Chino, California. The sources included sledgehammer, explosives, weight drop, projectile impacts, and various buffalo guns. A possible reflecting event can be interpreted at about 70 ms. At this particular test site, the lowly sledgehammer is among the best sources to provide data to see the possible reflection. Our previous work and that of our colleagues suggests that any source could dominate the comparison categories addressed here, given the appropriate set of site characteristics.

Field comparison of shallow seismic sources

Geophysics ◽  
1986 ◽  
Vol 51 (11) ◽  
pp. 2067-2092 ◽  
Author(s):  
R. D. Miller ◽  
S. E. Pullan ◽  
J. S. Waldner ◽  
F. P. Haeni
Keyword(s):  
Water Table ◽  
Seismic Source ◽  
Single Site ◽  
Seismic Sources ◽  
Shallow Seismic ◽  
Site Characteristics ◽  
Amplitude Spectra ◽  
Different Characteristics ◽  
Magnitude Difference ◽  
Selection Of

Choosing a seismic source for a shallow reflection survey can be the most pivotal decision for the engineering geophysicist. The intent of this paper is to present data that will assist in selection of a shallow seismic source best meeting the goals within the constraints of specific projects, particularly in areas where the water table is near the surface. The data were collected (and displayed as seismograms and amplitude spectra) for 15 different shallow seismic sources in October, 1985, at a single site in New Jersey; they show the different characteristics of each source. Considering the almost three orders of magnitude difference in total source energy between the largest and smallest source, we chose a display format that presented the data as objectively as possible, while still allowing direct source‐to‐source comparisons. Two strong reflections at about 100 and 130 ms probably mark the top and bottom of a clay unit 80 m below the surface at this site. Our previous work and that of our colleagues suggests that, given a specific set of site characteristics, any source could dominate the comparison categories addressed here.

scholarly journals Field comparison of shallow P‐wave seismic sources near Houston, Texas

Geophysics ◽  
1994 ◽  
Vol 59 (11) ◽  
pp. 1713-1728 ◽  
Author(s):  
Richard D. Miller ◽  
Susan E. Pullan ◽  
Don W. Steeples ◽  
James A. Hunter
Keyword(s):  
Water Table ◽  
Seismic Source ◽  
Dominant Frequency ◽  
P Wave ◽  
Near Surface ◽  
Site Characteristics ◽  
Water Well ◽  
Local Water ◽  
A Site ◽  
Different Sources

A shallow P‐wave seismic source comparison was conducted at a site near Houston, Texas where the depth to the water table was approximately 7 m, and near‐surface materials consisted of clays, sands, and gravels. Data from twelve different sources during this November 1991 comparison are displayed and analyzed. Reflection events are interpretable at about 40 ms on some 220-Hz analog low‐cut filtered field files, and at 60 ms on most 110‐ and 220-Hz analog low‐cut filtered field files. Calculations and local water well information suggest the 40-ms event is from the top of the water table. Subsurface explosive sources seem to possess the highest dominant frequency, broadest bandwidth, and recorded amplitudes and, therefore, have the greatest resolution potential at this site. Our previous work and that of our colleagues suggests that, given a specific set of site characteristics, any source could dominate the comparison categories addressed here.

scholarly journals Geochemistry and related studies of Clyde Estuary sediments

2017 ◽  
Vol 108 (2-3) ◽  
pp. 269-288 ◽  
Author(s):  
David G. Jones ◽  
Christopher H. Vane ◽  
Solveigh Lass-Evans ◽  
Simon Chenery ◽  
Bob Lister ◽  
...  
Keyword(s):  
Seismic Data ◽  
Surface Sediments ◽  
Sidescan Sonar ◽  
Near Surface ◽  
Glacial Sediments ◽  
Shallow Seismic ◽  
Limited Success ◽  
Shallow Layer ◽  
Quaternary History ◽  
Different Sources

ABSTRACTGeochemical and related studies have been made of near-surface sediments from the River Clyde estuary and adjoining areas, extending from Glasgow to the N, and W as far as the Holy Loch on the W coast of Scotland, UK. Multibeam echosounder, sidescan sonar and shallow seismic data, taken with core information, indicate that a shallow layer of modern sediment, often less than a metre thick, rests on earlier glacial and post-glacial sediments. The offshore Quaternary history can be aligned with onshore sequences, with the recognition of buried drumlins, settlement of muds from quieter water, probably behind an ice dam, and later tidal delta deposits. The geochemistry of contaminants within the cores also indicates shallow contaminated sediments, often resting on pristine pre-industrial deposits at depths less than 1m. The distribution of different contaminants with depth in the sediment, such as Pb (and Pb isotopes), organics and radionuclides, allow chronologies of contamination from different sources to be suggested. Dating was also attempted using microfossils, radiocarbon and 210Pb, but with limited success. Some of the spatial distribution of contaminants in the surface sediments can be related to grain-size variations. Contaminants are highest, both in absolute terms and in enrichment relative to the natural background, in the urban and inner estuary and in the Holy Loch, reflecting the concentration of industrial activity.

A field test of an electrodeless arc discharge, borehole seismic source

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1558-1564 ◽  
Author(s):  
Kenneth D. Mahrer ◽  
Brian J. Zook
Keyword(s):  
Field Test ◽  
Arc Discharge ◽  
Sensor Arrays ◽  
Seismic Source ◽  
Test Site ◽  
Near Surface ◽  
Single Firing ◽  
Borehole Seismic ◽  
High Degree ◽  
Repeatability Test

Waveforms generated by an impulsive, 1.2 kJ, seven‐conductor wireline electrodeless arc discharge borehole seismic source or sparker at Texaco’s Humble, TX field test site were recorded by three borehole sensor arrays: two free‐hanging hydrophone streamers in in‐line boreholes at 82 m and 170 m from the source well and a grouted, three‐component geophone string in a borehole 110 m from the source well. A repeatability test of the source, consisting of single firings of the source at a rate of 1 firing per 5 s, showed very clean, very strong, Ricker‐like wavelets. Despite a high‐degree of attenuation (exact value of Q is not known), the useful frequency passband of the wavelets was from 200 Hz to 1200 Hz for the data recorded by the 82-m offset hydrophones and 200 Hz to 500 Hz for the 170-m hydrophones. Using 62 single‐firing wavelets recorded in the 82-m offset well gave mean and median crosscorrelations greater than 0.96 with standard deviations less than 0.02. A stack test, consisting of 1, 2, 4, 8, 16, and 32-stacked waveforms, confirmed the shape, strong S/N ratio, and high correlation of the sparker output. The 32-stack, which took less than 3 minutes to generate, was recorded by the noisy, near-surface geophones at a raypath distance of nearly 300m.

An in‐hole shotgun source for engineering seismic surveys

Geophysics ◽  
1987 ◽  
Vol 52 (7) ◽  
pp. 985-996 ◽  
Author(s):  
S. E. Pullan ◽  
H. A. MacAulay
Keyword(s):  
Ground Surface ◽  
Seismic Source ◽  
Coarse Grained ◽  
Near Surface ◽  
Seismic Surveys ◽  
Fine Grained ◽  
Reflection Seismic ◽  
Weight Drop ◽  
Water Saturated ◽  
Excellent Source

We have conducted several source comparisons involving 12‐gauge and 8‐gauge Buffalo guns, a 7.3 kg sledgehammer, and a 75 kg weight drop. The results are strongly site‐dependent. We found that, when the near‐surface consisted of fine‐grained, water‐saturated sediments, the 12‐gauge Buffalo gun produced up to two orders of magnitude more energy than the conventional hammer across a broad frequency range. Under such conditions the gun produced the greatest improvement in energy between 200 and 400 Hz, where it yielded up to ten times more energy than the 75 kg weight drop. This indicates that the Buffalo gun may be particularly useful as a shallow reflection seismic source. However, at sites where the near‐surface materials were coarse‐grained and the water table was well below the ground surface, the advantages of using an in‐hole shotgun source as opposed to a hammer or weight drop were minimal. Nevertheless, in many areas we believe that the Buffalo gun is an excellent source for engineering seismic surveys. It is lightweight and portable (<5 kg), inexpensive to build (<$100 US), simple to use and maintain, and a good source of high‐frequency energy.

scholarly journals Seismoelectric imaging of the vadose zone of a sand aquifer

Geophysics ◽  
2007 ◽  
Vol 72 (6) ◽  
pp. A81-A85 ◽  
Author(s):  
J. Christian Dupuis ◽  
Karl E. Butler ◽  
Anton W. Kepic
Keyword(s):  
Water Table ◽  
Vadose Zone ◽  
Ground Penetrating Radar ◽  
Seismic Source ◽  
Unconfined Aquifer ◽  
Recording System ◽  
Sedimentary Environments ◽  
Sand Aquifer ◽  
Weight Drop ◽  
Ground Penetrating

We have acquired a [Formula: see text] seismoelectric section over an unconfined aquifer to demonstrate the effectiveness of interfacial signals at imaging interfaces in shallow sedimentary environments. The seismoelectric data were acquired by using a [Formula: see text] accelerated weight-drop source and a 24-channel seismoelectric recording system composed of grounded dipoles, preamplifiers, and seismographs. In the shot records, interfacial signals were remarkably clear; they arrived simultaneously at offsets as far as [Formula: see text] from the seismic source. The most prominent signal was generated at the water table at a depth of approximately [Formula: see text] and had peak amplitudes on the order of [Formula: see text]. A weaker response was generated at a shallower interface that is interpreted to be a water-retentive layer. The validity of these two laterally continuous events, and of other discontinuous events indicative of vadose-zone heterogeneity, is corroborated by the presence of reflections exhibiting similar characteristics in a ground-penetrating radar profile acquired along the same line.

A noninvasive shallow seismic source comparison on the Oak Ridge Reservation, Tennessee

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1318-1331 ◽  
Author(s):  
William E. Doll ◽  
Richard D. Miller ◽  
Jianghai Xia
Keyword(s):  
Seismic Reflection ◽  
Ground Surface ◽  
Seismic Source ◽  
Seismic Profile ◽  
Seismic Sources ◽  
Waste Site ◽  
Oak Ridge ◽  
Shallow Seismic ◽  
Wave Generator ◽  
Seismic Reflection Profiling

Nine seismic sources were compared in preparation for production seismic reflection profiling to about 500 m depth at a hazardous waste site on the Oak Ridge Reservation, Tennessee. Test data provided a 125-shotpoint common midpoint profile and a walkaway vertical seismic profile for each source. Sources tested included five swept sources and four impulsive sources. Eight of the sources were “noninvasive,” in that they would not penetrate the ground surface. When spectral whitening methods were applied to the data, the IVI Minivib provided the best image of the subsurface on the basis of continuity and clarity of reflections. Without prewhitening, the performance of the IVI Minivib and the Bison elastic wave generator were similar.

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