There are three main types of lava flow, categorized primarily by their surface texture: pahoehoe, ʻaʻā, and blocky lava.
Types of Lava Flows
Each type of lava flow exhibits unique characteristics influenced by factors such as lava viscosity, gas content, and flow rate.
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Pahoehoe: This type of lava flow is characterized by a smooth, undulating, and often ropy surface.
- It typically forms from basaltic lava with low viscosity.
- Pahoehoe flows can advance as a series of lobes or toes.
- The glassy surface is due to rapid cooling of the lava skin.
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ʻAʻā: ʻAʻā lava flows have a rough, jagged, and clinkery surface composed of fragmented lava.
- ʻAʻā typically forms from more viscous basaltic lava compared to pahoehoe.
- The rubble-like surface makes ʻaʻā flows difficult to walk across.
- The term "ʻaʻā" is of Hawaiian origin and refers to the sound one makes when walking on this type of lava.
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Blocky Lava: These lava flows are characterized by a surface covered with angular blocks.
- Blocky lava typically forms from more viscous lavas, such as andesite or dacite.
- The blocks are usually smooth-sided and can be several meters in size.
- Blocky flows tend to be thicker and move slower than pahoehoe or ʻaʻā flows.
In summary, the type of lava flow that forms is heavily dependent on the lava's composition and its resulting viscosity, affecting its texture and flow characteristics.
