Shield Volcanoes Explained: How Earth’s Largest Volcanoes Form

Have you ever wondered about the largest volcanoes on Earth? The ones that pour out rivers of fire rather than exploding?

Shield volcanoes are named so because of their shape, which resembles a shield lying on the ground. They are found wherever fluid, low-silica lava reaches the surface of a rocky planet.
Key features of shield volcano are:
👉 Built from low-viscosity basaltic lava that flows easily.
👉 Non-explosive eruptions that are effusive in nature.
👉 Enormous size (e.g., Mauna Kea is taller than Everest from base to peak).
👉 Lava moves slowly after the eruption of shield volcanoes.
👉 Shield volcanoes can be active for long periods and may have frequent eruptions.
Stages of shield volcano
There are typically four stages that shield volcanoes go through.
1. Pre-Shield
The shield volcano starts with low volume and infrequent eruptions in the first stage.
2. Shield
In the second stage, the volcano accumulates 95% of its mass through continuous eruptions.
3. Post Shield
The eruptions become slightly more explosive in the third stage.
4. Rejuvenation
The shield volcano becomes active once again in the last stage by erupting small volumes of lava infrequently. If this stage does not proceed, then the shield volcano will erode slowly over time.

Types of Lava
1. Pahoehoe lava
2. Aa lava