The primary properties of lava flow are its viscosity and speed, influenced heavily by composition, temperature, and the slope it flows upon. Lava flows generally move slowly.
Speed of Lava Flows
Lava flow speeds vary considerably, but are typically slow. Here's a breakdown:
- Typical Speed (Hawaiian Basaltic Flows): 0.40 km/h (0.25 mph)
- Maximum Speed (Steep Slopes): 10 to 48 km/h (6 to 30 mph)
Factors Influencing Lava Flow Properties:
- Viscosity: This is the lava's resistance to flow. Higher viscosity means slower movement. Viscosity is affected by:
- Composition: Lavas rich in silica (like rhyolite) are more viscous than those low in silica (like basalt).
- Temperature: Hotter lava is less viscous and flows more easily.
- Slope: Steeper slopes allow lava to flow faster due to gravity.
In summary, lava flow properties are defined mainly by the viscosity and speed of the flow, both of which are strongly influenced by composition (specifically silica content), temperature, and the gradient of the terrain.
