IS 1893(Part 1):2016 added in Cl 7.2.2 that buildings and portions shall be designed and constructed to resist at least the effects of design lateral force(Ah) in horizontal direction. The following procedure is to considered for the generation of coefficient of vertical seismic acceleration spectrum, Av.
Please note that (Sa/g) value is the highest one 2.5. Thus there is no requirement of having minimum base shear criteria imposed over here.