The bulk modulus increases with pressure because the interatomic distace decrease i.e. it is necesary a higher pressure to reduce the interatomic distance. That becomes from the definition of bulk modulus:

K=-V (dp/dV); if dp is positive and dV negative, then k>0. If dV is positive, K

This is the case for amorphous SiO2 : the compressibility increases with increasing pressure up to 2 GPa, and then decreases. This anomaly exists also in glasses with tetrahedrak units, such as amorphous BeF2, GeO2, Zn(PO3)2, etc.

Dear Santanu Pathak,  your question relates to fundamental mechanics of deformable solid body.   Bulk modulus and other moduli are determined within the framework of the linear theory there. According to these conditions, these moduli should be invariants concerning pressure and geometric sample forms.  Therefore,  these requirements should be observed in these experiments while their determination. Nonlinear processes occur during pressure increase. The influence of nonlinear effects can't be called as the change of elasticity moduli. Unfortunately, such an incorrect interpretation found place in many geophysical applications.  Those changes are nonlinear properties of the medium. So, thank you very much for a such interesting question. It was paid an attention to such kind of questions in my previous publications (i.e.  on coefficient ratio). If the question on this problem is  arisen, contact me a month later, please.