High-Frequency Seafloor Acoustics (Underwater Acoustics)

618 Pages·2006·7.85 MB·English

by  Darrell Jackson

Monograph Series in
UNDERWATER ACOUSTICS
Sponsored by Office of Naval Research
Editorial Board:Ralph R.Goodman,Ph.D.,Chair
Homer P.Bucker,Ph.D.
Ira Dyer,Ph.D.
Jeffrey A.Simmen,Ph.D.
Monograph Series in
UNDERWATER ACOUSTICS
In 2001 the Office ofNaval Research began a program to publish a selected monograph series in
the field ofunderwater acoustics.The series publishes in-depth reviews and analysis on the state
ofunderstanding ofthe physics ofsound in selected areas ofresearch.
The monograph series covers the most important topics in underwater sound in an in-depth,
critical, scholarly, and comprehensive fashion. It is intended to provide researchers with an
understanding of the physics of underwater sound,based on both theory and experiment.The
discussion ofimportant unanswered questions is encouraged.Topics ofparticular importance in
the field are low-frequency sound in the deep ocean,shallow-water acoustics,and ambient noise.
Sponsored by:
Office ofNaval Research
One Liberty Center
875 North Randolph Street,Suite 1425
Arlington,VA 22203-1995
E-mail:[email protected]
Series Editors:
Ralph R.Goodman,Ph.D. Homer P.Bucker,Ph.D.
Research Professor 808 Moana Drive
USM Department ofMarine Science San Diego,CA 92106
1020 Balch Boulevard E-mail:[email protected]
Stennis Space Center,MS 39529
E-mail:[email protected]
Ira Dyer,Ph.D. Jeffrey A.Simmen,Ph.D.
Weber Shaughness Professor ofOcean Applied Physics Laboratory
Engineering,Emeritus University ofWashington
Massachusetts Institute ofTechnology, 1013 NE 40th Street
Cambridge,MA 02139 Seattle,WA 98105-6698
E-mail:[email protected]
High-Frequency
Seafloor Acoustics
Darrell R. Jackson
University of Washington
Seattle,Washington
and
Michael D. Richardson
Naval Research Laboratory
Stennis Space Center,Mississippi
Darrell R.Jackson Michael D.Richardson
Applied Physics Laboratory Marine Geosciences Division
University of Washington Naval Research Laboratory
Henderson Hall Stennis Space Center,MS 49529-5004
1013 NE 40th Street e-mail:[email protected]
Seattle,WA 98105-5640
e-mail:[email protected]
Library ofCongress Control Number:200692906
ISBN-10:0-387-34154-4 e-ISBN-10:0-387-36945-7
ISBN-13:978-0-387-34154-5 e-ISBN-13:978-0-387-36945-7
Printed on acid-free paper.
© 2007 Springer Science+Business Media,LLC
All rights reserved.This work may not be translated or copied in whole or in part without the
written permission ofthe publisher (Springer Science+Business Media,LLC,233 Spring Street,
New York,NY 10013,USA),except for brief excerpts in connection with reviews or scholarly
analysis. Use in connection with any form of information storage and retrieval, electronic
adaptation,computer software,or by similar or dissimilar methodology now known or hereafter
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To Linda and Jeanne for their patience and support
during the lengthy preparation of this book
Series Preface
The efficacy of sound to penetrate the seas made acoustic systems in the past
century the leading tools for sensing objects in and measuring properties of
the seas. For over sixty years The United States Office of Naval Research
(ONR) has been a major sponsor of undersea research and development at
universities, national laboratories, and industrial organizations. Appro-
priately ONR is the sponsor of this monograph series.
The intent of the series is to summarize recent accomplishments in,and to
outline perspectives for, underwater acoustics in specific fields of research.
The general field has escalated in importance and spread broadly with rich-
ness and depth of understanding. It has also, quite naturally, become more
specialized. The goal of this series is to present monographs that critically
review both past and recent accomplishments in order to address the short-
comings in present understanding. In this way, these works will bridge the
gaps in understanding among the specialists and favorably color the direction
of new research and development. Each monograph is intended to be a
stand-alone advanced contribution to the field.We trust that the reader will
also find that each is a critical introduction to related specialized topics of
interest as well.
ONR has sponsored the series through grants to the authors.Authors are
selected by ONR based on the quality and relevance of each proposal and the
author’s experience in the field.The Editorial Board,selected by ONR,has,
at times,provided independent views to ONR in this process.Its sole official
role, however, is to judge the manuscripts before publication and to assist
each author at his request through the process with suggestions and broad
encouragement.
Ralph R.Goodman,Ph.D.
Ira Dyer,Ph.D.
Homer P.Bucker,Ph.D.
Jeffrey A.Simmen,Ph.D.
Acknowledgments
The support of the U.S. Office of Naval Research (ONR) is gratefully
acknowledged by both authors. Additional support was provided to DRJ by
theAppliedPhysicsLaboratoryoftheUniversityofWashingtonandtoMDR
by 6.1 Base funding from the Naval Research Laboratory. The authors are
especially indebted to the ONR Editorial Panel, Ralph Goodman (Chair),
Homer Bucker, Ira Dyer, and Jeffrey Simmen for their expert guidance and
patienceduringthepreparationofthismonograph.ColleaguesattheApplied
Physics Laboratory, the Naval Research Laboratory, and other institutions
contributed generously of their time, research results, figures, and informal
reviews of selected material. In this regard, special thanks are due Bernie
Beaudreau, Richard Bennett, Angus Best, Fred Bowles, Kevin Briggs, Joe
Gettrust, Alex Hay, Marcia Isakson, Anatoliy Ivakin, Jin-wook Kim, Dennis
Lindwall, Anthony Lyons, Eric Pouliquen, Richard Ray, Allan Reed, Dajun
Tang, Eric Thorsos, Kevin Williams, and Mike Zimmer.
Contents
1 Introduction.............................................. 1
1.1 Applications ........................................... 2
1.2 Research on Seafloor Scattering .......................... 3
1.3 Organization of Monograph.............................. 4
2 Basic Concepts and Definitions ........................... 7
2.1 Geophysical Properties.................................. 7
2.1.1 Physical Properties ............................... 8
2.1.2 Geoacoustic Properties............................ 9
2.1.3 Characterization of Gradients and Randomness ...... 11
2.2 Sediment Wave Theories ................................ 14
2.2.1 Fluid Theory .................................... 15
2.2.2 Elastic Theory ................................... 16
2.2.3 Poroelastic Theory ............................... 17
2.3 Reflection and Scattering................................ 17
2.3.1 Reflection ....................................... 18
2.3.2 Scattering ....................................... 21
3 The Nature of Marine Sediments ......................... 29
3.1 The Origin and Classification of Coastal Sediments ......... 30
3.2 Sediment Structure ..................................... 32
3.2.1 Clay Microstructure .............................. 34
3.2.2 Fabric of Siliciclastic Sands ........................ 41
3.2.3 Carbonate Structure.............................. 45
3.3 Bubbles in Sediment .................................... 51
3.4 Effects of Hydrodynamic and Biological Processes .......... 57
3.4.1 Hydrodynamic Processes .......................... 60
3.4.2 Biological Processes .............................. 65
3.5 Research Issues ........................................ 72
4 Physical Properties ....................................... 75
4.1 Sediment Grain Size Distribution......................... 76
4.2 Sand Grain Morphology................................. 89
4.3 Phase Relationships: Porosity, Void Ratio, Water Content,
and Bulk Density....................................... 92
xii Contents
4.4 Sediment Conductance .................................. 99
4.4.1 Permeability..................................... 100
4.4.2 Electrical Resistivity.............................. 104
4.4.3 Thermal Conductivity ............................ 106
4.4.4 Conductance Measured in Consolidation and Packing
Experiments ..................................... 110
4.5 Grain Properties ....................................... 110
4.5.1 Density of Sediment Particles ...................... 110
4.5.2 Bulk Modulus of Sediment Particles ................ 114
4.6 Factors Affecting Fluid Motion........................... 118
4.7 Pore Water Properties .................................. 119
4.7.1 Pore Water Density............................... 120
4.7.2 Pore Water Viscosity ............................. 120
4.7.3 Sound Speed and Attenuation...................... 121
4.8 Research Issues ........................................ 122
5 Geoacoustic Properties ................................... 123
5.1 Compressional Wave Speed and Attenuation ............... 125
5.1.1 Measurement Techniques .......................... 125
5.1.2 Data Sets and Regression Relations................. 130
5.1.3 Core Data Set ................................... 131
5.1.4 Core Data Regressions ............................ 134
5.1.5 Gradients ....................................... 136
5.1.6 In Situ Data Regressions .......................... 139
5.1.7 Comparison with Other Regressions ................ 142
5.1.8 Index of Impedance Regressions .................... 146
5.2 Shear Wave Speed and Attenuation....................... 151
5.2.1 Laboratory Measurement Techniques ............... 152
5.2.2 In Situ Measurement Techniques ................... 154
5.2.3 Shear Wave Data and Regressions .................. 155
5.3 Biot’s “Slow Wave”..................................... 161
5.4 Sound Speed and Attenuation versus Frequency ............ 165
5.5 Bulk Density Regressions................................ 167
5.6 Properties of Rock...................................... 169
5.7 Research Issues ........................................ 170
6 Seafloor Roughness ....................................... 171
6.1 Statistical Characterization of Seafloor Roughness .......... 173
6.2 Measurement of Seafloor Roughness ...................... 176
6.3 Examples of Seafloor Roughness Spectra .................. 182
6.4 Temporal Variability in Seafloor Roughness................ 184
6.5 Validity of Power-Law Assumption for Roughness Spectra ... 191
6.6 Relationships between Roughness and Sediment Physical
Properties ............................................. 193
6.7 Relationship between Spectral Parameters ................. 195