The normal force of the tank wall to the floor will shear across the acrylic if it's not perfectly flat. Pressure outwards is normal to the tank wall relative to the water, but if this force goes diagonally through the floor, that's bad.
If the tank burst due to it shearing off of its base then it is not the glass that has the problem; it’s the connection to the base. This might sound pedantic but the OP said the forces on the GLASS were ill-distributed. The most important part of after the fact disaster analysis from an engineering context is being excruciatingly specific about the performance of structural elements.
