where Y is in g, b1= 0.393, b2= 0.576, b3= -0.107, b5= -0.899, bV= -0.200, VA= 1112m∕s,
h = 6.91km and σ = 0.612.
Use three site classes:
Average Vs= 700m∕s, 23 records
Average Vs= 400m∕s, 41 records
Average Vs= 200m∕s, 48 records
Use Vs measurements where available (10 stations, 22 records) but mainly classify using approximate
methods. Note that correspondence between average Vs values for each site class and more widely accepted
soil categories is tenuous.
Focal depths from 0 to 111.0km. State that all earthquakes were shallow crustal events. Only 4 records
come from earthquakes with reported focal depths > 33km.
Faulting mechanism distribution is: normal (12 earthquakes, 14 records), strike-slip (34 earthquakes,
82 records), reverse (2 earthquakes, 5 records), unknown (9 earthquakes, 11 records). Note that poor
distribution w.r.t. mechanism does not allow its effect to be modelled.
Use only records from earthquakes with Mw≥ 4.0 to include only more reliably recorded events.
Data reasonably well distribution w.r.t. M and d for d < 100km.
Data from main shocks. Exclude data from aftershocks, in particular that from the 1999 Kocaeli and Düzce
aftershocks because of high nonlinear soil behaviour observed during the mainshocks near the recording
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.
State equations can be used for 4.0 ≤ Mw≤ 7.5 and df≤ 250km.
Find no significant trends in residuals w.r.t. M or d for all data and for each site category.
Find that observed ground motions for the Kocaeli earthquake are well predicted.