Effusive eruption from effusive to explosive, due to pressure build up below the lava dome. Effusive eruption An effusive eruption is a type of volcanic eruption in which lava steadily flows out of a volcano onto the ground. There are two major groupings of eruptions: effusive and explosive. Effusive eruption differs from explosive eruption, wherein magma is violently fragmented and rapidly expelled from a volcano. Effusive eruptions are most common in basaltic magmas, but they also occur in intermediate and felsic magmas. These eruptions form lava flows and lava domes, each of which vary in shape, length, and width. Deep in the
Lava River Cave ago. The source is believed to be near Mokst Butte southeast of the entrance. The same volcanic flow that formed the cave underlies much of the Bend area and almost reaches Redmond, Oregon. However, the specific vent that created the cave has been buried by several younger flows. The Lava River Cave was created by lava flowing downhill from a volcanic vent. The lava flowed northwest from the vent toward the Deschutes River. The flow began as a river of lava flowing in an open channel. Eventually, a lava crust solidified over the top of the flowing lava. This formed