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THE International Scientific Series VOL. LVI. EARTHQUAKES AND OTHER EARTH MOVEMENTS BY JOHN MILNE PROFESSOR OF MINING- AND GEOLOGY IN THE IMPERIAL COLLBfn?2^^ TOKIO, JAPAN WITH THIRTY-EIGHT FIGURE^ LONDON" KEGAN PAUL, TRENCH, & CO., 1 PATERNOSTER SQUARE 1886 (The right $ of translation, anti of reproduction are reserved) preface:- In the following pages it has been my object to give a systematic account of various Earth Movements. These comprise Earthquakes, or the sudden violent movements of the ground; Earth Tremors, or minute move¬ ments which escape our attention by tjpe smallness of their amplitude; Earth pulsations, or movements which are overlooked on account of the length of their period; and lastly, Earth Oscillations, or movements of long period and large amplitude which attract so much attention from their geological importance. It is difficult to separate these Earth Movements from each other, because they are phenomena which only differ in degree, and which are intimately associated in their occurrence and in their origin. Because Earthquakes are phenomena which have at¬ tracted a universal attention since the earliest times, and about them so many observations have been made, they are treated of at considerable length. As very much of what might be said about the other Earth Movements is common to what is said about Earth- VI PKEFACE. quakes, it has been # possible to make the description of these phenomena comparatively short. The scheme which has been adopted will be under¬ stood from the following table :— I. Earthquakes. 1. Introduction. 2. Seismometrv. ((a) Theoretically. J (//) As deduced from experiments, 3. Earthquake Motion j (c) As deduced from actual Eartli- \ quakes. j (a) On land. 4. Earthquake Effects [ (b) In the ocean. 5. Determination of Earthquake origins. f (a) In space. 6. Distribution « E^unta, <‘> I diurnal, &c.) 7. Cause of Earthquakes. S. Earthquake prediction and warning. II. Earth Tremors. III. Earth Pulsations. TV. Earth Oscillations. In some instances the grouping of phenomena according to the above scheme may be found inaccurate, as, for example, in the chapters referring to the effects and causes of Earthquakes. This arises from the fact that the relationship between Earthquakes and other Earth phenomena are not well understood. Thus the sudden elevation of a coast line and an accompanying earthquake may be related, either as effect and cause, or vice versa, or they may both be the effect of a third phenomenon. PREFACE. vii Much of what is said respecting Earthquake motion will show how little accurate knowledge we have about these disturbances. Had I been writing in England, and, therefore, been in a position to make references to libraries and persons who are authorities on subjects connected with Seismology, the following pages might have been made more complete, and inaccuracies avoided. : A large proportion of the material embodied in the following pages is founded on experiments and observations made during an eight years’ residence in Japan, where I have had the opportunity of recording an earthquake every week. The writer to whom I am chiefly indebted is Mr. Kobert Mallet. Hot being in a position to refer to original memoirs, I have drawn many illustrations from the works of Professor Karl Fuchs and M. S. di Eossi. These, and other writers to whom reference has been made, are given in an appendix. For seeing these pages through the press, my thanks are due to Mr. Thomas G-ray, who, when residing in Japan, did so much for the advancement of- observational Seis¬ mology. For advice and assistance in devising experiments, I tender my thanks to my colleagues, Professor T. Alexander, Mr. T. Fujioka, and to my late colleague, Professor John Perry. For assistance in the actual observation of Earth¬ quakes, I have to thank my friends in various parts of Japan, especially Mr. J. Bissett and Mr. T. Talbot, of Yokohama. For assistance in obtaining information from viii PBEFACE. Italian sources I have to thank Dr. F. Du Bois, from German sources Professor C. Netto, and from Japanese sources Mr. B. H. Chamberlain. For help in carrying out experiments, I am indebted to the liberality of the British Association, the Geological Society of London, the Meteorological and Telegraph departments of Japan, and to the officers of my own institution, the Imperial College of Engineering. And, lastly, I offer my sincere thanks to those gentle¬ men who have taken part in the establishment and working of the Seismological Society of Japan, and to my publishers, whose, liberality has enabled me to place the labours of residents in the Far East before the European public. John Milne. Tokio, Japax : June 30, 1SS3. CONTENTS. CHAPTER I. INTRODUCTION. PAGE Relationship of man to nature—The aspect of a country is de¬ pendent on geological £>henomena—Earthquakes an important geological phenomenon—Relationship of seismology to the sciences and arts—Earth movements other than earthquakes— Seismological literature—(Writings of Perrey, Mallet, Eastern writings, the Philosophical Transactions of the Royal Society, the ‘Gentleman’s Magazine,’ the Bible, Plerodotus, Pliny, Hop¬ kins, Yon Hoff, Humboldt, Schmidt, Seebach, Lasaulx, Fuchs, Palmieri, Bertelli, Seismological Society of Japan)—Seismo¬ logical terminology. ... 1 CHAPTER II. SEISMOMETRY. Nature of earthquake vibrations—Many instruments called seismo¬ meters only seismoscopes—Eastern seismoscopes, columns, pro¬ jection seismometers — Vessels filled with liquid—Palmieri’s mercury tubes —The ship seismoscope—The cacciatore—Pendu¬ lum instruments of Kreil, Wagner, Ewing, and Gray—Bracket seismographs—West’s parallel motion instrument—Gray’s con¬ ical pendulums, rolling spheres, and cylinders—Yerbeck’s ball and plate seismograph—The principle of Perry and Ayrton— Vertical motion instruments—Record receiver—Time*recording apparatus—The Gray and Milne seismograph . . . .12 X CONTENTS. CHAPTER. III. EARTHQUAKE MOTION DISCUSSED THEORETICALLY. PAGE Ideas of the ancients (the views of Travagini, Hooke, Woodward, Stuckeley, Mitchell, Young, Mallet)—Nature of elastic waves and vibrations—Possible causes of disturbance in the earth’s crust—The time of vibration of an earth particle—Velocity and acceleration of a particle—Propagation of a disturbance as de¬ termined by experiments upon the elastic moduli of rocks—The intensity of an earthquake—Area of greatest overturning mo¬ ment— Earthquake waves—Red exion, refraction, and in fcerference of waves—Radiation of a disturbance.41 CHAPTER IY. EARTHQUAKE MOTION AS DEDUCED FROM EXPERIMENT. Experiments with falling weights—Experiments with explosives —Results obtained from experiments—Relative motion of two adjacent points—The effect of hills and excavations upon the propagation of vibrations—The intensity of artificial disturb¬ ances—Velocity with which earth vibrations are propagated— Experiments of Mallet—Experiments of Abbot—Experiments in Japan—Mallet’s results—Abbot’s results—Results obtained in Japan.57 CHAPTER Y. EARTHQUAKE MOTION AS DEDUCED FROM OBSERVATION ON EARTHQUAKES. Result of feelings—The direction of motion—Instruments as in¬ dicators of direction—Duration of an earthquake—Period of vibration— The amplitude of earth movements—Side of greatest motion—Intensity of earthquakes—Velocity and acceleration of an earth particle—Absolute intensity of an earthquake—Radi¬ ation of an earthquake—Velocity of propagation . . .67 CONTENTS. Xl CHAPTER VI. EFFECTS PRODUCED BY EARTHQUAKES UPON BUILDINGS. PAGE The destruction of buildings is not irregular—Cracks in buildings- Buildings in Tokio—Relation of destruction to earthquake motion—Measurement of relative motion of parts of a building shaken by an earthquake—Prevention of cracks- Direction of cracks—The pitch of roofs—Relative position of openings in a wall—The last house in a row—The swing of buildings—Prin¬ ciple of relative vibrational periods.96 CHAPTER VII. effects produced upon buildings (continued). Types of buildings used in earthquake countries—In Japan, in Italy, in South America, in Caraccas—Typical houses for earthquake countries—Destruction due to the nature of underlying rocks— The swing of mountains—Want of support on the face of hills— Earthquake shadows—Destruction due to the interference of waves—Earthquake bridges—Examples of earthquake effects— Protection of buildings—General conclusions . . . 122 CHAPTER VIII. EFFECTS OF EARTHQUAKES ON LAND. 1. Cracks and fissures—Materials discharged from fissures—Ex¬ planation of fissure phenomena. 2. Disturbances in lakes, rivers, springs, wells, fumaroles, &c.—Explanation of these latter phe¬ nomena. 3. Permanent displacement of ground—On coast lines —Level tracts—Among mountains—Explanation of these move¬ ments .146 CHAPTER IX. DISTURBANCES IN THE OCEAN. Sea vibrations—Cause of vibratory blows—Sea waves: preceding earthquakes; succeeding earthquakes—Magnitude of waves—