In this paper a theoretical relation is presented to model attenuation of strong ground motion. The relation
is based on the Brune spectra for the near and far-field and uses parameters obtained from acceleration
records, such as seismic moment, spectral decay factor, duration and stress drop. Attenuation of horizontal
peak ground acceleration as a function of epicentral distance is presented for both horizontal components.
The theoretical model is applied to PGA data from two Icelandic earthquakes (Mw 6.6 and 6.5). For
comparison the model is also applied to data from European and North-American earthquakes. The
earthquakes are shallow (depth < 15 km) and with magnitude in the range M 6.4-6.6. The records chosen
are from rock and stiff soil sites. The Icelandic earthquakes are strike-slip but the other data come from
normal and oblique faults as well. The attenuation curves for the earthquakes are found to have a similar
slope. The acceleration levels are lower by a factor of 0.7 for the Icelandic data. Empirical attenuation
relations found in the literature are found to provide a poor fit to the data.