Table 3 Site classifications scheme according to Pitilakis et al. (2018)

A

 ≤ 0.2 s

V_S30 or ≥ 800

Surface weathered layer H < 5 m

Seismic bedrock

B₁

0.1–0.3 s

\(V_{s,avg}\): 350–600

V_S,30: 400–760

H < 30 m

Very dense sand and/or stiff clay

B₂

0.3–0.6 s

\(V_{S,avg}\): 400–550

V_S,30: 350–500

30 m < H < 120 m

C₁

0.6–1.0 s

\(V_{S,avg}\): 400–600

V_S,30: 350–450

H > 60 m

Medium dense sand and/or stiff clay

C₂

0.3–0.7 s

\(V_{S,avg}\): 250–450

V_S30: 250–400

20 m < H < 60 m

C₃

0.7–1.4 s

\(V_{S,avg}\): 300–500

V_S,30: 200–350

H > 60 m

D

 ≤ 1.4 s

\(V_{S,avg}\): 200–400

V_S,30: 150–300

Soft soil

E

0.1–0.5 s

\(V_{S,avg}\): 160–300

5 m < H < 20 m

Soft soils overlaying rock (or site class A)

X

Special soils requiring site-specific evaluations (\(V_{S,avg}\) < 160 m/s)