The Nature of Tsunamis

Résumé du livre

Original contains color plates: All ASTIA reproductions will be in black and white. Original may be seen in ASTIA Hq. DESCRIPTORS: *Seismic waves, *Ocean bottom, Earthquakes, Classification, Hazards, Inten sity, Geological survey, Northern hemisphere, Southern hemisphere. Identifiers: Tsunamis, Tidal waves. Current knowledge on important characteristics of tsunamis and their modes of generation isASSEMBLED. A review of seismic source mechanisms discloses that evidence is in favor of molar upthrusting or down-drop of the sea-bed, over an extensive fault-line or bottom area, being the principal mode by which dangerous tsunamis are generated. Submarine landsliding and volcanic eruption in open water are likely to be less effective mechanisms, though underwater slumping in confined areas such as bays or channels and as. Noteworthy tsunamis are unlikely to result from earthquakes of magnitude less than M = 6.4 (Richter scale). Dangerous tsunamis may be expected when M exceeds about 7.75. Laws of wave height decay and period increase with distance are established on theoretical and experimental grounds. (Author).