Faulting mechanism distribution is: normal (12 earthquakes, 14 records), strike-slip (33 earthquakes, 81
records) and reverse (2 earthquakes, 5 records). Note that poor distribution w.r.t. mechanism does not
allow its effect to be modelled.
Use only records from earthquakes with Mw≥ 4.5 to emphasize motions having greatest engineering
interest and to include only more reliably recorded events. Include data from one Mw4.2 earthquake
because of high vertical acceleration (31mg) recorded.
Data reasonably well distribution w.r.t. M and d for d < 100km.
Data mainly recorded in small and medium-sized buildings ≤ 3 storeys. Note that these buildings modify
recorded motions and this is an unavoidable uncertainty of the study.
Data from main shocks. Exclude data from aftershocks, in particular that from the 1999 Kocaeli and
Düzce aftershocks because these records are from free-field stations, which do not want to commingle with
Exclude a few records for which PGA caused by main shock is < 10mg. Exclude data from aftershocks
from the same stations.
Note that data used is of varying quality and could be affected by errors.
Include cubic term for M dependence to compensate for the controversial effects of sparsity of Turkish
data. Find that it gives a better fit.
Use two-step method of Ambraseys et al. (1996) to find site coefficients C6 and C7 after exploratory
analysis to find regression method that gives the best estimates and the lowest σ.
State equations can be used for 4.5 ≤ Mw≤ 7.4 and df≤ 200km.
Find no significant trends in residuals w.r.t. M or d for all data and for each site category except for a few
high residuals for soil and soft soil records at df> 100km.
Compute individual σs for each site class.
Find that observed ground motions for the Kocaeli earthquake are well predicted.