Note that some data (Turkish and Japanese) are associated with liquefaction phenomena and so probably
Choose functional form to include effect of amplitude saturation close to source.
Note that negative Q values obtained in some ground motion estimation equations may be due to the lack
of amplitude saturation terms.
Do not investigate effect of rupture mechanism, directivity, and the hanging wall effect because of a lack
Use same set of data as Berge-Thierry et al. (2003) but with the addition of records from the 1995
Hyogo-ken Nanbu and 1999 Kocaeli earthquakes, which are used to help constrain the near-source
characteristics. In total use 399 records from west Eurasia, 162 from USA, 154 from Hyogo-ken Nanbu and
25 from Kocaeli.
Remove records from distances greater than the distance at which the predicted PGA is less than 10cm∕s2
(the average trigger level plus the standard error of observation) as predicted by a previously derived
ground motion prediction equation that agrees well with the 1995 Hyogo-ken Nanbu and 1999 Kocaeli
earthquakes although they note the process should be iterative.
Use only records from earthquakes with M ≥ 5.5 so as to allow the use of a linear magnitude dependence.
Due to the nonlinear functional form adopt a iterative method to find d(f) and e(f). However, due to
the lack of near-source data an accurate value of e(f) cannot be found therefore set e(f) to 0.42, which
gives accelerations that agree with the observed peak accelerations in the 1995 Hyogo-ken Nanbu and 1999
Bandpass filter records with cut-offs of 0.25 and 25Hz. Note that due to the presence of many records from
analogue instruments the results for frequencies higher than 10Hz are less reliable than those for lower
Find that for frequencies > 0.4Hz the b(f) coefficient corresponds to positive Q values. For lower frequencies
the value of b(f) correspond to negative Q values, which note could be due to instrumental noise or the
effect of surface waves that are not well represented by the functional form adopted.
Note that the small difference between predicted rock and soil motions may be due to intrinsic rock
amplification due to rock weathering or inappropriate site classification for some records (e.g. those from
the 1999 Kocaeli earthquake, which are all considered to be on soil).
Plot residuals with respect to regional origin (Hyogo-ken Nanbu, USA, western Eurasian and Kocaeli) and
find no clear bias or trend.
Note that most of the used near-fault records come from strike-slip earthquakes and so the equation may
be only should be used for prediction of strike-slip motions.
Note that the site classification scheme adopted is very basic but lack information for more sophisticated