Modern Seismology (Paperback)

MODERN SEISMOLOGY - 1913 - PREFATORY NOTE. - ONLY a week after this book had been handed to the pub- lisher, the scientific world had to mourn the loss of Dr. John Milne, who entered into Rest on 31 July, 1913. It was my melancholy privilege on 5 August to pay a last tribute to one who had proved a very kind friend. The assembling of a large congregation in St. Thornass Church, Newport, Isle of Wight, was an eloquent testimony to the love and esteem with which Milne was regarded by those among whom his daily life was spent. No one will deny that Milne was truly the father of modern Seismology. He founded the subject, he developed it well-nigh single-handed, and he lived to see the importance of his life work recognised not only by his fellow-countrymen but by the whole civilized world. The credit for several important points in modern Seis- mology is sometimes assigned to others, and it was only Milnes greatness of heart that prevented him from claiming the priority that was rightly his. But his claim to scientific fame rests not on details, for he made the whole subject. As Prince Galitzin remarked at Cambridge only a year ago, There are not many questions of modern Seismology that have not been attacked by Milne long before any other person had thought about them . G. W. W. 6- CONTENTS. SEISMOMETRY. CHAP. PAGB I. General Dynamical Theory of Seismographs ., I I I. Methods of attaining Sensitiveness, Damping, Registration . 7 111. Chief Types of Seismographs in Actual Use. Milne, Omori, Bosch, Wiechert, Galitzin . . 16 IV. Standardization of Seismographs, including Theory of Mechanical and Electromagnetic Registration . . . 21 V. Installation of Seismographs and Consideration ofDevelop- ment of Instruments . 30 SEISMOGEOPHYSICS. VI. Theory of a Solid Isotropic Earth . 37 VII. Interpretation of Seismograms and the Interior of the Earth . 48 VIII. Determination of Epicentre and Focus . 63 IX. Seismic Effects other than those due to Earthquakes . 72 X. Statistical . 83 LIST OF PLATES PLATE I. Milne Horizontal Seismograph for one Hori- zontal Component . . facinq age 2. Wiechert Astatic Inverted Pendulum Seismo- graph for two Horizontal Components ., , 3. Galitzin Aperiodic Horizontal Component Seis- mograph, with Galvanometer and Record- ing Cylinder for electromagnetic registra- tion . 7, Y 4. Galitzin pkriodic Vertical Component Seismograph for electromagnetic registration ., ,, 5. Time Curves after Zoppritz . ace 6. Showing Maximum Depth of Seismic Rays as Function of Epicentral Distance after Zoppritz ., 7A. Portion of Record at Pulkowa, September 18, 1910, showing microseismic movement . facing9ag.e 7B. Specimen Record reduced showing Tilt pro- duced by Tidal loading . 9 8. Earthquake in Yap, West Caroline Islands. Milne Seismogram, Eskdalemuir, August 16-17, 191 I. N-S Component . . foZCowiryage g. Earthquake in Yap, West Caroline Islands. Milne Seismogram, Eskdalemuir, August 16-1 7, I 91 I. E-W Component . y3 79 ro. Specimen Record - Wiechert Seismograph 1200 kg. with ink registration ., , YY I I. Specimen Record-Galitzin Horizontal ponent Seismograph . 12. Specimen Record-Galitzin Horizontal Com- ponent Seismograph . r g. Specimen Record-Galitzin Vertical ponent Seismograph . vii In the ocket. THE present volume owes its existence to Sir J. J. ThomsonJs suggestion that I should write an account of the present position of seismological investigation.The book is written from the point of view of Seismology as a branch of Physics, and particularly as it is determined by observatory conditions...