ABSTRACT
In this paper a seismological-engineering approach is suggested to estimate the wide spectrum for distant earthquakes. The method combines the seismological relations of magnitude and displacement and digital records of VBB and FBA for the estimation of long period (2∼20 sec) part of the spectrum with the currently available strong ground motion data from the analog accelerograph records for the short period (0.1 – 3 sec) part. Error and limitation of the results derived from the digital records are also discussed. The limited available strong ground motion data obtained by digital instruments are finally used to show the adequacy of the results obtained. It seems possible to provide dependable spectra of ground motion up to 10 to 20 sec with accuracy comparable to that from the definition of the earthquake magnitude and also comparable to the accuracy of the spectrum at shorter period part.
