Book contents
- Frontmatter
- Contents
- Preface
- 1 Seismology, the science of earthquakes
- 2 Fundamental equations of an elastic medium
- 3 Elastic waves
- 4 Normal mode theory
- 5 Reflection and refraction
- 6 Ray theory. Media of constant velocity
- 7 Ray theory. Media of variable velocity
- 8 Ray propagation in a spherical medium
- 9 Travel times and the structure of the Earth
- 10 Surface waves
- 11 Wave propagation in layered media
- 12 Wave dispersion. Phase and group velocities
- 13 Free oscillations of the Earth
- 14 Anelasticity and anisotropy
- 15 Focal parameters of earthquakes
- 16 The source mechanism
- 17 The seismic moment tensor
- 18 Models of fracture
- 19 Methods of determination of source mechanisms
- 20 Seismicity, seismotectonics, and seismic risk
- 21 Seismographs and seismograms
- Appendix 1 Vectors and tensors
- Appendix 2 Cyclindrical and spherical coordinates
- Appendix 3 Bessel and Legendre functions
- Appendix 4 Fourier transforms
- Appendix 5 Parameters of the Earth
- Appendix 6 The interior of the Earth
- Appendix 7 Important earthquakes
- Appendix 8 Problems and exercises
- Bibliography
- References
- Index
1 - Seismology, the science of earthquakes
- Frontmatter
- Contents
- Preface
- 1 Seismology, the science of earthquakes
- 2 Fundamental equations of an elastic medium
- 3 Elastic waves
- 4 Normal mode theory
- 5 Reflection and refraction
- 6 Ray theory. Media of constant velocity
- 7 Ray theory. Media of variable velocity
- 8 Ray propagation in a spherical medium
- 9 Travel times and the structure of the Earth
- 10 Surface waves
- 11 Wave propagation in layered media
- 12 Wave dispersion. Phase and group velocities
- 13 Free oscillations of the Earth
- 14 Anelasticity and anisotropy
- 15 Focal parameters of earthquakes
- 16 The source mechanism
- 17 The seismic moment tensor
- 18 Models of fracture
- 19 Methods of determination of source mechanisms
- 20 Seismicity, seismotectonics, and seismic risk
- 21 Seismographs and seismograms
- Appendix 1 Vectors and tensors
- Appendix 2 Cyclindrical and spherical coordinates
- Appendix 3 Bessel and Legendre functions
- Appendix 4 Fourier transforms
- Appendix 5 Parameters of the Earth
- Appendix 6 The interior of the Earth
- Appendix 7 Important earthquakes
- Appendix 8 Problems and exercises
- Bibliography
- References
- Index
Summary
The historical development
The term seismology is derived from two Greek words, seismos, shaking, and logos, science or treatise. Earthquakes were called seismos tes ges in Greek, literally shaking of the Earth; the Latin term is terrae motus, and from the equivalents of these two terms come the words used in occidental languages. Seismology means, then, the science of the shaking of the Earth or the science of earthquakes. The term seismology and similar ones in other occidental languages (séismologie, sismologia, sismología, Seismologie, etc.) started to be used around the middle of the nineteenth century. Information about the main historical developments of seismology can be found in each chapter; a very short overview is given in the following paragraphs.
In antiquity, the first rational explanations of earthquakes, beyond mythical stories, are from Greek natural philosophers. Aristotle (in the fourth century BC) discussed the nature and origin of earthquakes in the second book of his treatise on meteors (Meteorologicorum libri IV). The term meteors was used by the ancient Greeks for a variety of phenomena believed to take place somewhere above the Earth's surface, such as rain, wind, thunder, lightning, comets, and also earthquakes and volcanic eruptions. The term meteorology derives from this word, but in modern use it refers only to atmospheric phenomena. Aristotle, following other Greek authors, such as Anaxagoras, Empedocles, and Democritus, proposed that the cause of earthquakes consists in the shaking of the Earth due to dry heated vapors underground or winds trapped in its interior and trying to leave toward the exterior.
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- Principles of Seismology , pp. 1 - 9Publisher: Cambridge University PressPrint publication year: 2000