Geofisica pura e applicata

, Volume 43, Issue 1, pp 45–74 | Cite as

On coda waves of earthquakes

  • Sushil Chandra Das Gupta


Coda waves viz. the tail portion of an earthquake record have been observed and analysed byCarder, Macelwane and others. They showed that the periods of such waves increase with the increase of epicentral distances.Carder observed that these waves have very little transverse component so that these may be considered as of the type of Rayleigh waves. RecentlyOmote showed that the Coda waves contain three periodsT1,T2,T3 of whichT1 increases with epi-central distances as observed by previous observers. ButT2,T3 remain constant for all earthquakes from different epicentral distances.Omote tried to explain this phenomenon by considering that the surface of the earth consists of several layers andT2,T3 are free oscillation periods of the surface layers.T1 period has been explained bySezawa and also byJeffreys which has been shown byGutenberg. The author has attempted to explain the periodsT2,T3 by considering passage of cracks at the focal region. The Rayleigh wave character of Coda waves and low velocity of such waves have been explained.


Surface Layer Oscillation Period Rayleigh Wave Focal Region Epicentral Distance 
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Copyright information

© Istituto Geofisico Italiano 1959

Authors and Affiliations

  • Sushil Chandra Das Gupta
    • 1
  1. 1.Presidency CollegeCalcutta 12(India)

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