An Investigation on Soil Amplification through Site Factors Used in Seismic Design Codes

Table 5

Site coefficients for the midperiod (S₁) region.

Local site classes	Site coefficient S1 for code, average, and for 84% safety
	0.05	0.10	0.20	0.30	0.40	0.50	0.60	0.70
ZB	—/0.81/1.40	0.80/0.77/1.45	0.80/0.78/1.32	0.80/0.76/1.42	0.80/0.73/1.31	0.80/0.73/1.29	0.80/0.72/1.28	—/0.69/1.27
ZC	—/1.08/1.48	1.50/1.11/1.59	1.50/1.12/1.45	1.50/1.05/1.46	1.50/1.08/1.33	1.50/1.08/1.32	1.40/1.10/1.31	—/1.10/1.31
ZD	—/1.51/1.54	2.40/1.54/1.65	2.20/1.50/1.55	2.00/1.60/1.63	1.90/1.39/1.46	1.80/1.19/1.41	1.70/1.16/1.46	—/1.10/1.52
ZE	—/1.98/1.99	4.20/1.42/1.66	3.30/1.24/1.67	2.80/1.19/1.72	2.40/0.90/1.53	2.20/0.74/1.44	2.00/0.72/1.40	—/0.62/1.38
ZF	—/2.26/2.32	—/1.55/1.69	—/1.49/1.55	—/1.21/1.47	—/1.24/1.33	—/1.19/1.32	—/1.14/1.31	—/1.12/1.32

Group not included in the codes.