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L Symposium on Microseisms Held at Arden House Harriman, N. Y. 4-6 September 1952 SPONSORED BY THE OFFICE OF NAVAL RESEARCH, AND THE GEOPHYSICAL RESEARCH DIRECTORATE OF THE U. S. AIR FORCE NATIONAL ACADEMY OF SCIENCES, NATIONAL RESEARCH COUNCIL WASHINGTON, D. C. DECEMBER, 1953
FOREWORD Interest in the subject of microseisms has been growing in recent years because of their possible use in storm detection and location. Although there is no doubt that microseisms of certain periods are related to frontal and storm activity in some way, there is no general agreement as to the nature of the relationship. When microseisms are observed in connection with atmospheric activity, the coupling medium seems to be a water body. There are many and interesting explanations of the coupling mechanism and the means by which microseisms are generated. No single explanation is wholly satisfactory and perhaps none can be more satis- factory without the accumulation of more extensive and more refined data. This situation in the field of investigation of microseims is perhaps not different from that in other fields of naturally occurring geophysical phenomena. However, because microseisms are the subject of such inten- sive research by a small but enthusiastic group of investigators and also because the phenomena probably have a potential application other than storm detection, it was considered that a symposium on the subject would provide a worthwhile opportunity for bringing together the existing obser- vations in this field, for appraising their significance, and for stimulating further studies through the give and take of discussion. The Office of Naval Research in joint effort with the Geophysical Research Division of the U. S. Air Force initiated arrangements for such a meeting. The symposium which was held at Arden House, Harriman, New York, on 4, 5, and 6 September, 1952, was organized by Dr. R. C. Gibbs of the National Research Council with the advice and assistance of an ad hoc group of interested scientists, chief among whom in thought and effort was Dr. Perry Byerly of the University of California at Berkeley who served also as moderator of the symposium. The National Research Council joins with the military research agencies, who provided the sup- port for this symposium, in extending special thanks to Dr. Byerly for his outstanding contribution to the organization of the program and its direc- tion at the symposium. The symposium brought together many of the out- standing and currently active investigators on microseisms from both this country and abroad. Those attending were: t John N. Adkins Office of Naval Research, Washington, D. C. Markus Bath Meteorological Institute, Uppsala, Sweden Perry Byerly University of California, Berkeley Joseph Caldwell Army Beach Erosion Board, Washington, D. C. Dean S. Carder U. S. Coast and Geodetic Survey, Washington, D. C. Frank Crowley Air Force Cambridge Research Center, Mass. G. E. R. Deacon Natl. Institute of Oceanography, Teddington, England Jacob E. Dinger Naval Research Laboratory, Washington, D. C. William L. Donn Brooklyn College, Brooklyn, N. Y. H. P. Gauvin Air Force Cambridge Research Center, Mass. R. C. Gibbs National Research Council, Washington, D. C. Marion H. Gilmore U. S. Naval Air Station, Miami, Florida Beno Gutenberg Seismological Laboratory, Pasadena, Calif. Norman A. Haskell Air Force Cambridge Research Center, Mass. J. Hughes Office of Naval Research, Washington, D. C. Columbus O'D. Iselin Woods Hole Oceanographic Institution, Mass. W. S. Jardetzky Lament Geological Observatory, Palisades, N. Y. Gordon G. Lill Office of Naval Research, Washington, D. C, M. S. Longuet-Higgins Trinity College, Cambridge, England John Joseph Lynch, S. J. Fordham University, New York, N. Y. James B. Macelwane, S. J. St. Louis University, St. Louis, Mo. Ben S. Melton Air Force Headquarters, Washington, D. C. J. E. Oliver Lamont Geological Observatory, Palisades, N. Y. James A. Peoples Air Force Cambridge Research Center, Mass. iii
Frank Press Lamont Geological Observatory, Palisades, N. Y. J. Emilio Ramirez, S. J. Estacion Sismologica, Bogota, Colombia Carl F. Romney Geotechnical Corporation, Troy, N. Y. J. G. Scholte Meteorologisch Instituut, The Netherlands Florence W. van Straten Navy Department, Washington, D. C. James T. Wilson University of Michigan, Ann Arbor, Michigan J. Lamar Worzel Lamont Geological Observatory, Palisades, N. Y. The papers given at the symposium are included in this volume. They stimulated much interesting discussion and speculation, some of which is also included in these proceedings. The discussions did not end at the conclusion of each day's meeting but continued after the dinner hour and far into the night. Since September, 1952, many interesting papers on microseisms have appeared in the literature. The sponsors of the symposium would like to feel that, at least in a small way, the discus- sions at the symposium were responsible for the continued emphasis on microseism research which is evident in the many recent scientific papers and reports on the subject. GORDON G. LILL, Head, Geophysics Branch, Office of Naval Research iv
EDITOR'S PREFACE At the time of the Symposium the undersigned were given the task of editing for publication the presented papers, formal discussions, and comments from the floor. The latter, of course, posed the most serious problems, and we elected to handle them in the following manner: Each of us took rather complete notes and at the end of each half-day session these were used to select those remarks which we felt should be given in the exact words of the speaker and they were then asked to write out or dictate their remarks. Short questions, answers, or statements which seemed completely clear have been taken from our notes. For a number of these, however, the content was checked with the originator during informal discussions. We wish to thank all of the participants for the splendid coopera- tion given us in compiling the informal discussions and we hope that in the process of editing and compiling we have not done injustice to any of their statements. The papers and the formal discussions presented after each of them, have been edited as little as was consistent with the problems of printing, referencing, etc. Some consideration was given to rationalizing the various notations but this seemed unnecessary and unwise. Although we went over all of the papers jointly, most of the editing for the first half was done by Dr. Press and most of the editing for the second half by Dr. Wilson. The manuscripts came to us in good order and for this we wish to thank the authors. Finally we wish to express our appreciation to Dr. R. C. Gibbs who has handled many of the problems and details that would normally have fallen to us. JAMES T. WILSON FRANK PRESS
Attendants at SYMPOSIUM ON MICROSEISMS held at Arden House, Harriman, New York, September 4-6, 1952 (front, left to right) Dr. Perry Byerly Dr. Florence Van Straten Mr. William Donn Dr. J. E. Dinger Dr. James T. Wilson Dr. John N. Adkins Dr. W. S. Jardetzky Dr. M. S. Longuet-Higgins Dr. J. G. Scholte Dr. Norman A. Haskell Dr. Beno Gutenberg Dr. R. C. Gibbs Dr. Carl F. Romney Dr. Jack E. Oliver Mr. Frank Crowley (back row, left to right) Dr. Marcus Bath Dr. Ben S. Melton Rev. James B. Macelwane, S. J. Dr. G. E. R. Deacon Dr. Marion H. Gilmore Dr. John J. Lynch, S. J. Dr. Frank Press Dr. J. A. Peoples Dr. Dean S. Carder Dr. J. E. Ramirez, S. J. University of California, Berkeley, Calif. Navy Department, Washington, D. C. Brooklyn College, Brooklyn, N. Y. Naval Research Laboratory, Washington, D. C. University of Michigan, Ann Arbor, Michigan Office of Naval Research, Washington, D. C. Lamont Geological Observatory, Palisades, N. Y. Trinity College, Cambridge, England Meterologisch Instituut, The Netherlands Air Force Cambridge Research Center, Mass. Seismological Laboratory, Pasadena, Calif. National Research Ccuncil, Washington, D. C. Geotechnical Corporation, Troy, N. Y. Lamont Geological Laboratory, Palisades, N. Y. Air Force Cambridge Research Center, Mass. Meteorological Institute, Uppsala, Sweden Air Force Headquarters, Washington, D. C. St. Louis University, St. Louis, Mo. Natl. Institute of Oceanography, Teddington, England U. S. Naval Air Station, Miami, Florida Fordham University, New York, N. Y. Lamont Geological Observatory, Palisades, N. Y. Air Force Cambridge Research Center, Mass. U. S. Coast and Geodetic Survey, Washington, D. C. Estacion Sismologica, Bogota, Colombia Vi
CONTENTS Foreword iii Editor's Preface v Moderator's Comments 1 Sketch of the History of Microseismology 3 Tripartite Stations and Direction of Approach of Microseisms 9 Amplitude Distribution of Storm Microseisms 20 Microseismic Period Spectra and Related Problems in the Scandinavian Area 56 Can Sea Waves Cause Microseisms 74 Storm and Surf Microseisms 94 The Ocean as an Acoustic System 109 On the Theories of Microseisms 114
