Monte Carlo computer simulations of ice VII and ice VIII phases have been undertaken using the four-point transferable intermolecular potential model of water. By following thermodynamic paths similar to those used experimentally, ice is decompressed resulting in an amorphous phase. These phases are compared to the high density amorphous phase formed upon compression of ice I-h and are found to have very similar structures. By cooling liquid water along the water/I-h melting line a high density amorphous phase was also generated. (C) 2004 American Institute of Physics.