The Types of Lava Flows; ‘A‘ā, Pāhoehoe, and More

Summary

This video explores the fascinating world of volcanic lava flows, discussing various types such as Pāhoehoe, A‘ā, pillow lava, and blocky lava. It explains the distinct characteristics of each, including differences in texture, viscosity, and the eruption conditions that cause their formation. Viewers will learn about the smooth, ropy texture of Pāhoehoe, the jagged, clinkery surface of A‘ā, and the unique pillow lava formed underwater. The video also highlights the blocky lava that forms thick lobes and even tall lava domes. The diverse nature of these lava flows offers a captivating glimpse into volcanic activity.

Takeaways

• 😀 Watching a volcano erupt is an exciting and fascinating experience.
• 😀 Lava flows from volcanoes can vary in thickness, from a few inches to over 2,000 feet in some rare cases.
• 😀 Lava flows have different textures, which depend on the composition of the rock they contain.
• 😀 The first type of lava flow discussed is pāhoehoe, which is basaltic and has a smooth, ropy texture.
• 😀 Pāhoehoe lava flows are associated with low viscosity and low lava effusion rates, often forming smooth, ropy masses.
• 😀 A‘ā is another type of lava flow, characterized by a rough, jagged, and clinkery surface.
• 😀 A‘ā lava flows are associated with higher lava effusion rates, producing flows that sound like breaking glass as they move.
• 😀 Underwater volcanic eruptions can produce pillow lava, which forms rounded chunks that resemble pillows.
• 😀 When an eruption has a higher silica content, blocky lava forms, which consists of large, rough blocks with smoother surfaces than a‘ā lava.
• 😀 Blocky lava flows can form thick lobes that extend over a mile and may pile up near the vent to create tall lava domes.
• 😀 Blocky lava flows can sometimes be more than 1,000 feet thick, and they may contain chunks of obsidian.

Q & A

What is the primary characteristic of pāhoehoe lava flows?

Pāhoehoe lava flows are typically basaltic in composition, low in silica, and have low viscosity. They advance in ropy masses and leave behind a smooth, ropy texture when they cool.

How do pāhoehoe lava flows differ from a‘ā lava flows?

Pāhoehoe lava flows are smooth and ropy due to their low viscosity, while a‘ā lava flows are rough, jagged, and clinkery, resulting from higher effusion rates and higher viscosity.

What does a‘ā lava sound like as it advances?

A‘ā lava flows often sound like breaking glass due to the rough and clinkery nature of the flow.

Where was a significant a‘ā lava flow observed recently?

A notable a‘ā lava flow was observed during the Mauna Loa eruption in 2022.

What is 'pillow lava' and how does it form?

Pillow lava forms during underwater eruptions, creating rounded chunks of material that appear like fluffed-up pillows. These rounded formations are densely packed together.

How does the composition of lava affect its flow type?

Lavas with lower silica content, such as basalt, typically produce pāhoehoe or a‘ā flows, while higher silica content, like that found in andesite lava, tends to form blocky lava flows.

What are the characteristics of blocky lava flows?

Blocky lava flows are rough but have a smoother appearance than a‘ā flows. When cooled, they form several-foot-wide blocks of material and can accumulate into thick lobes or lava domes.

How thick can blocky lava flows get?

Blocky lava flows can be extremely thick, with some reaching over 1,000 feet thick and extending over a mile in length.

What is one indicator that a lava flow might be blocky in nature?

If a lava flow contains chunks of obsidian, it is most likely a blocky lava flow.

What type of volcanic eruptions are associated with blocky lava flows?

Blocky lava flows are typically associated with eruptions that have higher silica content, such as those from stratovolcanoes or eruptions involving andesite lava.