Book 12, Question 21
Why Is Fresh Lava Dangerous Long After It Stops Glowing?
Fresh lava can look dark and solid after the top cools, but a thick crust can hide very hot rock underneath. That is why people stay far away from new lava, even when nothing glows. Always follow grown-ups and local warnings.
More fun facts
- How thick a lava flow is matters most for how fast it cools, though wind, rain and air temperature also play a part.
- Kilauea's 2018 lava flows, about 10 to 15 meters thick, could take roughly 8 months to 1.5 years to turn completely solid.
- Flows 20 to 30 meters thick could take about 2.5 to 6 years to solidify.
- The thickest 2018 flows on land, about 55 meters thick, may take around 20 years to become fully solid.
- After a 1959 eruption, the Kilauea Iki lava lake, about 135 meters deep, took about 35 years to harden, and its inside may still glow hot.
- When rain seeps into cracks and reaches hot rock inside, it turns to steam, and this steaming can last for decades.
- Even after lava becomes solid, it takes much longer to cool all the way down to air temperature.
Sources: U.S. Geological Survey
Questions kids ask
Why can't I walk on new lava once it stops glowing?
The inside can stay extremely hot for years, and cracks can release steam, so new lava is still dangerous.
Why does old lava steam when it rains?
Rainwater seeps into cracks, hits hot rock inside and turns into steam.