Question

how does magma viscosity affect the shape of volcanoes

Answer 1

Magma is hot liquid present under the surface of the Earth. The three layers of Earth are inner core, outer core, mantle, and crust. Most of the magma present in mantle. This magma coming out from holes or cracks in the crust causes volcanic eruption and when magma flows onto surface of Earth, it is called as lava.

Viscosity is defined as resistance of fluid to flow

The low viscosity of magma results in more fluid behavior and flows like water and high viscosity results in less fluidity such as thick paste.

The viscosity means thickness of magma erupts from volcano affects the shape of the volcano.

- Steep slopes volcanoes formed from viscous magma.

- Flatter volcanoes formed from less viscous magma which means that flows easily.

High viscosity makes escape of gas difficult and low viscosity makes escape gas peacefully. Therefore, more viscous magma produces more violent eruption and less viscous magma will be fluid and thus the eruption will not more explosive.

Shield volcanoes such as in Hawai' have flatter slopes. Stratovolcanoes such as Cascades are steeper.