One of the key reasons for Federation was to achieve a united defence force which could better protect Australia. Around the 1880s, the Australian colonies had become increasingly concerned over the close proximity of foreign powers.
Split and merge into it. Answered by The Community. Making the world better, one answer at a time. Dissolved gases trapped in the magma provides the force that causes magma to erupt to the surface. Magma is molten material before it reaches the surface and is lava.
Confidence votes 83.6K. The two main factors are the viscosity and the gas content of the magma. explosive eruptions usually occur when magma approaches the surface and dissolved gasses bubble out so rapidly that it escapes explosively, creating clouds of ash and pumice. If there isn't enough gas this can't happen.onfidence votes 83.6K. The two main factors are the viscosity and the gas content of the magma. explosive eruptions usually occur when magma approaches the surface and dissolved gasses bubble out so rapidly that it escapes explosively, creating clouds of ash and pumice. If there isn't enough gas this can't happen.