The pieces of magma are shot into the air during the explosion. Some bombs can be the size of a small car. C Gases Gases, primarily in the form of steam, are released from volcanoes during eruptions. All eruptions, explosive or nonexplosive, are accompanied by the release of volcanic gas. The sudden escape of high-pressure volcanic gas from magma is the driving force for eruptions.
Gases come from the magma itself or from the hot magma coming into contact with water in the ground.
Volcanic plumes can appear dark during an eruption because the gases are mixed with dark-colored materials such as tephra. In general, the more viscous, or stiffer, the lava, the more explosive the eruptive activity. During explosive eruptions, the lava erupted is torn into shreds, forming a variety of fragmental or pyroclastic materials depending on the physical state of the lava and on the force of the explosions. Explosive eruptions can eject a large amount of material into the air. Nonexplosive eruptions produce lava flows and eject very little pyroclastic material into the air.