When magma flows or erupts onto Earth’s surface, it is called lava. Like solid rock, magma is a mixture of minerals. It also contains small amounts of dissolved gases such as water vapor, carbon dioxide, and sulfur. The high temperatures and pressure under Earth’s crust keep magma in its fluid state.

Pahoehoe has a smooth wavy surface that resembles twisted rope. It advances by extruding molten toes of lava beneath a thin, flexible crust. As it travels pahoehoe lava often changes to blocky flows called aa. The surface of aa lava is brittle and rough, covered in broken lava blocks called clinkers.

The viscosity of magma depends upon its silica content and temperature.

Magma forms from partial melting of mantle rocks. As the rocks move upward (or have water added to them), they start to melt a little bit. Eventually the pressure from these bubbles is stronger than the surrounding solid rock and this surrounding rock fractures, allowing the magma to get to the surface.

Volcanic Eruptions: High Silica Lava with high silica content is thick and viscous and does not readily flow. Lava rises up toward the surface but is too thick to squeeze through the cracks and fissures in the Earth. As lava continues to rise upward, pressure continues to build.

But in answer to your question, you can increase the viscosity of water by dissolving minerals salts. You can also try a polymer that will dissolve in water such as polyvinyl alcohol (PVA). Heating and stirring will help it to dissolve.

One of the most viscous liquids known is pitch, also known as bitumen, asphalt, or tar. Demonstrating its flow and measuring its viscosity is the subject of the longest continuously running scientific experiment, begun in 1927 at the University of Queensland in Australia.

graphene