What are viscous lava domes?
I don't know about viscous, but a lava dome is a steep-sided dome of thick lava extruding from a volcanic vent.
a viscous lava dome is when the lava from the volcano contains alot of silica. Viscous=sticky. So the lava cools quickly of the sides of the volcano. And often a viscous lava dome volcano is explosive.
There are two types of volcanic domes. First, there are lava domes. A lava dome forms when extremely viscous lava is solwly extruded from the ground, but is too viscous to flow away. The second type is a cryptodome. These form when magma gathers ast a shallow depth and essentially inflates that ground above it.
A lava dome volcano is also referred to as dome volcano. It forms when lava blocks the vent. The lava cools, then breaks apart, new lava covers the cooled lava (molten rock) which makes a dome shape. The lava involved in these domes is extremely viscous, and so does not readily flow away from the source.