1. What determines the Characteristics of lava?
Just like with any other liquid, the speed and distance lava travels depends on its viscosity or thickness.
Thicker lava moves slower and thus travels a shorter distance in the time it cools and solidifies.
1. Temperature- Adding heat to a substance tends to make it thinner and more fluid in movement. Thus, hotter lava will be thinner than cooler lava if all else is the same.
What determines the Characteristics of lava?
2. Content – The ingredients within lava can also effect its thickness and thus how it behaves. Specifically, lava containing high levels of silica will usually be thicker and slower.

2. The silica content of magma also helps determine whether the volcanic eruption will be “quiet” or “explosive”
Low Silica = Quiet Eruption
Ex.; Hawaii
High Silica = Explosive Eruption
Ex.; Mt. St. Helens, Washington

3. Explosive eruptions result in something called a Pyroclastic Flow
Pyroclastic flow – Mixture of super heated rock and gas moving down the side of a volcano. It destroys everything in its way.
Temperature
Speed
1000°C +
100mph +
Pyroclastic Cloud (eruption column)
Pyroclastic Flow

4. Some Specific Dangers…
Gases –poisonous to animals, crops, and water supplies. Also increases rapid global warming.
Ash – causes buildings to collapse, limits evacuation and transportation. Can cause global climate change.
Heat – Heat from lava and pyroclastic flows can melt snow causing flooding, avalanches and Lahars – a mudflow or rapid moving “rivers” of hot cement. The heat generated can also start fires.
Any Pleasant Aspects?

5. Geothermal energy – Clean reliable energy from naturally heated water
Geothermal energy – Clean reliable energy from naturally heated water. Provides electricity for millions!
Mineral Rich Soil – After many years the ash deposited from an eruption makes the surrounding land very lush and fertile.

6. Science describes the activity of volcanoes in 3 ways:
Active – “Awake”. Is erupting or may erupt in the near future.
Dormant – “Sleeping”. May erupt in the distant future.
Extinct – “Dead” Unlikely to erupt ever again