ASTM D7128-05(2010)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7128 −05 (Reapproved 2010)
Standard Guide for
Using the Seismic-Reflection Method for Shallow
Subsurface Investigation
This standard is issued under the fixed designation D7128; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope familiar with the relevant material in this guide, the references
cited in the text, and Guides D420, D653, D2845, D4428/
1.1 Purpose and Application:
D4428M, Practice D5088, Guides D5608, D5730, D5753,
1.1.1 Thisguidesummarizesthetechnique,equipment,field
D6235, and D6429.
procedures,dataprocessing,andinterpretationmethodsforthe
1.2.2 This guide is limited to two-dimensional (2-D) shal-
assessmentofshallowsubsurfaceconditionsusingtheseismic-
low seismic-reflection measurements made on land. The
reflection method.
seismic-reflection method can be adapted for a wide variety of
1.1.2 Seismic reflection measurements as described in this
special uses: on land, within a borehole, on water, and in three
guide are applicable in mapping shallow subsurface conditions
dimensions (3-D). However, a discussion of these specialized
for various uses including geologic (1), geotechnical, hydro-
2 adaptations of reflection measurements is not included in this
geologic (2), and environmental (3). The seismic-reflection
guide.
method is used to map, detect, and delineate geologic condi-
1.2.3 This guide provides information to help understand
tions including the bedrock surface, confining layers
the concepts and application of the seismic-reflection method
(aquitards), faults, lithologic stratigraphy, voids, water table,
to a wide range of geotechnical, engineering, and groundwater
fracture systems, and layer geometry (folds). The primary
problems.
application of the seismic-reflection method is the mapping of
1.2.4 The approaches suggested in this guide for the
lateral continuity of lithologic units and, in general, detection
seismic-reflection method are commonly used, widely
of change in acoustic properties in the subsurface.
accepted, and proven; however, other approaches or modifica-
1.1.3 Thisguidewillfocusontheseismic-reflectionmethod
tions to the seismic-reflection method that are technically
as it is applied to the near surface. Near-surface seismic
sound may be equally suited.
reflection applications are based on the same principles as
1.2.5 Technical limitations of the seismic-reflection method
those used for deeper seismic reflection surveying, but ac-
are discussed in 5.4.
cepted practices can differ in several respects. Near-surface
1.2.6 Thisguidediscussesbothcompressional(P)andshear
seismic-reflectiondataaregenerallyhigh-resolution(dominant
(S)wavereflectionmethods.Whereapplicable,thedistinctions
frequency above 80 Hz) and image depths from around6mto
between the two methods will be pointed out in this guide.
as much as several hundred meters. Investigations shallower
1.3 This guide offers an organized collection of information
than 6 m have occasionally been undertaken, but these should
be considered experimental. or a series of options and does not recommend a specific
course of action. This document cannot replace education or
1.2 Limitations:
experienceandshouldbeusedinconjunctionwithprofessional
1.2.1 This guide provides an overview of the shallow
judgment. Not all aspects of this guide may be applicable in all
seismic-reflectionmethod,butitdoesnotaddressthedetailsof
circumstances. This guide is not intended to represent or
seismic theory, field procedures, data processing, or interpre-
replace the standard of care by which the adequacy of a given
tation of the data. Numerous references are included for that
professional service must be judged, nor should this document
purpose and are considered an essential part of this guide. It is
be applied without consideration for a project’s many unique
recommendedthattheuseroftheseismic-reflectionmethodbe
aspects. The word “Standard” in the title of this guide means
only that the document has been approved through the ASTM
consensus process.
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock
and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
1.4 The values stated in SI units are regarded as standard.
Characterization.
The values given in parentheses are inch-pound units, which
Current edition approved May 1, 2010. Published September 2010. Originally
approved in 2005. Last previous edition approved in 2005 as D7128–05. DOI:
are provided for information only and are not considered
10.1520/D7128-05R10.
standard.
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. 1.5 Precautions:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7128−05 (2010)
1.5.1 It is the responsibility of the user of this guide to 3.2 Definitions Specific to This Guide
follow any precautions within the equipment manufacturer’s
3.2.1 acoustic impedance—product of seismic compres-
recommendations, establish appropriate health and safety
sionalwavevelocityanddensity.Compressionalwavevelocity
practices, and consider the safety and regulatory implications
of a material is dictated by its bulk modulus, shear modulus,
when explosives or any high-energy (mechanical or chemical)
and density. Seismic impedance is the more general term for
sources are used.
the product of seismic velocity and density.
1.5.2 If the method is applied at sites with hazardous
3.2.2 automatic gain control (AGC)—trace amplitude ad-
materials, operations, or equipment, it is the responsibility of
justment that varies as a function of time and the amplitude of
the user of this guide to establish appropriate safety and health
adjacent data points. Amplitude adjustment changing the out-
practices and determine the applicability of any regulations
put amplitude so that at least one sample is at full scale
prior to use.
deflection within a selected moving window (moving in time).
1.5.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.3 body waves—P- and S-waves that travel through the
body of a medium, as opposed to surface waves which travel
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- along the surface of a half-space.
bility of regulatory limitations prior to use.
3.2.4 bulk modulus (elastic constant)—the resistance of a
material to change its volume in response to the hydrostatic
2. Referenced Documents
load. Bulk modulus (K) is also known as the modulus of
2.1 ASTM Standards:
compression.
D420GuidetoSiteCharacterizationforEngineeringDesign
4 3.2.5 check shot survey—direct measurement of traveltime
and Construction Purposes (Withdrawn 2011)
between the surface and a given depth. Usually sources on the
D653Terminology Relating to Soil, Rock, and Contained
surface are recorded by a seismic receiver in a well to
Fluids
determine the time-to-depth relationships at a specified loca-
D2845Test Method for Laboratory Determination of Pulse
tion. Also referred to as downhole survey.
Velocities and Ultrasonic Elastic Constants of Rock
D3740Practice for Minimum Requirements for Agencies 3.2.6 coded source—aseismicenergy-producingdevicethat
Engaged in Testing and/or Inspection of Soil and Rock as
delivers energy throughout a given time in a predetermined or
Used in Engineering Design and Construction predicted fashion.
D4428/D4428MTest Methods for Crosshole Seismic Test-
3.2.7 common mid-point (CMP) or common depth point
ing
(CDP) method—a recording-processing method in which each
D5088Practice for Decontamination of Field Equipment
source is recorded at a number of geophone locations and each
Used at Waste Sites
geophone location is used to record from a number of source
D5608Practices for Decontamination of Field Equipment
locations. After corrections, these data traces are combined
Used at Low Level Radioactive Waste Sites
(stacked) to provide a common-midpoint section approximat-
D5730Guide for Site Characterization for Environmental
ing a coincident source and receiver at each location. The
Purposes With Emphasis on Soil, Rock, the Vadose Zone
objective is to attenuate random effects and events whose
and Groundwater (Withdrawn 2013)
dependence on offset is different from that of primary reflec-
D5753Guide for Planning and Conducting Borehole Geo-
tions.
physical Logging
3.2.8 compressional wave velocity—also known as P-wave
D5777Guide for Using the Seismic Refraction Method for
velocity. In seismic usage, velocity refers to the propagation
Subsurface Investigation
rate of a seismic wave without implying any direction, that is,
D6235Practice for Expedited Site Characterization of Va-
velocity is a property of the medium. Particle displacement of
dose Zone and Groundwater Contamination at Hazardous
a compressional wave is in the direction of propagation.
Waste Contaminated Sites
D6429Guide for Selecting Surface Geophysical Methods
3.2.9 dynamic range—the ratio of the maximum reading to
D6432Guide for Using the Surface Ground Penetrating
the minimum reading which can be recorded by and read from
Radar Method for Subsurface Investigation
an instrument without change of scale. It is also referred to as
the ability of a system to record very large and very small
3. Terminology
amplitude signals and subsequently recover them. Integral to
3.1 Definitions—For general terms, SeeTerminology D653.
the concept of dynamic range is the systemsAnalog to Digital
Additional technical terms used in this guide are defined in
converter (A/D). A systems A/D is rated according to the
Refs (4) and (5) .
number of bits the analog signal is segmented into to form the
digital word. A/D converters in modern seismographs usually
range from 16 to 24 bits.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3.2.10 fold (or redundancy)—the multiplicity of common-
Standards volume information, refer to the standard’s Document Summary page on
midpoint data or the number of midpoints per bin. Where the
the ASTM website.
midpoint is the same for 12 source/receiver pairs, the stack is
The last approved version of this historical standard is referenced on
www.astm.org. referred to as “12-fold” or 1200 percent.
D7128−05 (2010)
3.2.11 G-force—measure of acceleration relative to the 3.2.22 seismic impedance—product of seismic wave veloc-
gravitational force of the earth. ity and density. Different from acoustic impedance as it
includes shear waves and surface waves where acoustic
3.2.12 impedance contrast—ratio of the seismic impedance
impedance, by strict definition, includes only compressional
across a boundary. Seismic impedance of the lower layer
waves.
dividedbytheseismicimpedanceoftheupperlayer.Avalueof
3.2.23 seismic sensor—receivers designed to couple to the
1 implies total transmittance.Values increase or decrease from
earth and record vibrations (for example, geophones,
1 as the contrast increases, that is, more energy reflection from
accelerometers, hydrophones).
a boundary. Values less than 1 are indicative of a negative
reflectivity or reversed reflection wavelet polarity.
3.2.24 seismic sensor group (spread)—multiple receivers
connected to a single recording channel, generally deployed in
3.2.13 normal moveout (NMO)—the difference in
an array designed to enhance or attenuate specific energy.
reflection-arrival time as a function of shot-to-geophone dis-
tance because the geophone is not located at the source point. 3.2.25 seismogram—a seismic record or section.
It is the additional traveltime required because of offset,
3.2.26 shear modulus (G) (elastic constant)—the ratio of
assuming that the reflecting bed is not dipping and that
shear stress to shear strain of a material as a result of loading
raypaths are straight lines.This leads to a hyperbolic shape for
and is also known as the rigidity modulus, equivalent to the
a reflection.
second Lamé constant m mentioned in books on continuum
theory.Forsmalldeformations,Hooke’slawholdsandstrainis
3.2.14 normal moveout velocity (stacking velocity)—
proportional to stress.
velocity to a given reflector calculated from normal-moveout
measurements, assuming a constant-velocity model. Because 3.2.27 shear wave velocity (S-wave velocity)—speed of
the raypath actually curves as the velocity changes, fitting a energy traveling with particle motion perpendicular to its
hyperbola assumes that the actual velocity distribution is direction of propagation (see Eq 2).
equivalent to a constant NMO velocity, but the NMO velocity
3.2.28 shot gather—a side-by-side display of seismic traces
changes with the offset. However, the assumption often pro-
that have a common source location.Also referred to as “field
vides an adequate solution for offsets less than the reflector
files.”
depth. Used to calculate NMO corrections to common-
3.2.29 source to seismic sensor offset—thedistancefromthe
midpoint gathers prior to stacking.
source-point to the seismic sensor or to the center of a seismic
3.2.15 Nyquist frequency—also known as the aliasing or
sensor (group) spread.
folding frequency, is equal to half the sampling frequency or
3.2.30 takeout—a connection point on a multiconductor
rate.Anyfrequencyarrivingattherecordinginstrumentgreater
cable where seismic sensors can be connected. Takeouts are
than the Nyquist will be aliased to a lower frequency and
usuallyphysicallypolarizedtoreducethelikelihoodofmaking
cannot be recovered.
the connection backwards.
3.2.16 optimum window—range of offsets between source
3.2.31 taptest—gentlytouchingareceiverwhilemonitoring
and receiver that provide reflections with the best signal-to-
on real-time display, to qualitatively appraise sensor response.
noise ratio.
3.2.32 twist test—light rotational pressure applied to each
3.2.17 Poisson’s ratio—the ratio of the transverse contrac- seismic sensor to ensure no motion and, therefore, a solid
tion to the fractional longitudinal extension when a rod is
ground coupling point.
stretched. If density is known, specifying Poisson’s ratio is
3.2.33 wavetrain (wavefield)—(1) spatial perturbations at a
equivalenttospecifyingtheratioof V /V ,where V and V are
s p s p
given time that result from passage of a wave; and (2) all
S-and P-wavevelocities.Valuesordinarilyrangefrom0.5(no
components of seismic energy traveling through the earth as
shear strength, for exam
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