Wills Site Classification

This is the site-type classification scheme developed by Wills et al. (2000, Bull. Seism. Soc. Am., vol. 90, pp S187-S208.

The categories and their Vs30 equivalents are:

Site Class	Vs30 range (m/sec)
B	>760
BC	555-1000
C	360-760
CD	270-555
D	180-360
DE	90-270
E	<180