pure and applied geophysics

, Volume 130, Issue 1, pp 83–97 | Cite as

Simple method for combined studies of macroseismic intensities and focal mechanisms

  • J. Zahradník


A simple method is presented for the computation of theoretical models of the macroseismic field, approximately valid close to the epicentre of a weak crustal earthquake. It is assumed that the intensity is logarithmically proportional to the energy flux of a complete directS wave. A circular source is used, whose energy-flux directivity is weak and thus simply predictable. The focal mechanism influences the solution through standard far-field double-couple radiation patterns. For the wave propagation in the layered crust the ray method is used, and a simple absorption correction is applied. Conversion coefficients at the earth's surface are included. To speed up repeated computations of the theoretical macroseismic fields for varying focal mechanisms, the ray quantities are computed (and stored) separately. This makes the program fast and simple enough even for routine applications on small microcomputers, whenever observed macroseismic fields, focal mechanisms, and hypocentre locations need joint interpretation.

Key words

macroseismic data focal mechanism circular source energy flow directivity local effects 


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Copyright information

© Birkhäuser Verlag 1989

Authors and Affiliations

  • J. Zahradník
    • 1
  1. 1.Institute of GeophysicsCharles UniversityPraha 8Czechoslovakia

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