A Closer Look at Lava

Kim Moldofsky is the publisher of The Maker Mom and STEM Kids Chicago.

As the smell of sulfur filled our nostrils, my friends and I watched an effusive flow of fiery lava push through a barely cooled, charred crust just yards away from us on a rocky beach back in 1989. A bit further down and off to the side of our group, the creeping lava met the ocean, producing a series of loud cracks and sizzles, not to mention flying debris, as each new wave crashed ashore.

The scene was dramatic and primal. We were watching the birth of land- the visible expansion of Hawaii’s Big Island at Hawai'i Volcanoes National Park (You know I’m a fan of our National Parks. For many of us, this is one of the more logistically challenging parks to visit, but it’s definitely a bucket list item.)

Looking back on that afternoon, I recall being caught in nature’s thrall, in awe of the creation I witnessed. The current news of the Kilauea volcano eruption is a stark reminder that the awesome powers of nature can be destructive, too.

On May 3, the Kilauea volcano dramatically erupted. Unlike the effusive flow I witnessed, this was an explosive eruption. That is, one during which magma was torn apart as it rose and pyroclasts (bits of lava, hot ash, and gases including sulfur dioxide) shot up and out in the manner of a Hollywood blockbuster.

Since then, flowing lava and toxic gases have plagued parts of the island. Neighborhoods were evacuated, houses and property have been destroyed, and lives have been disrupted.

Red Lava is the Coolest

As lava seeps across the Earth’s surface, observe the color to get a sense of its temperature. Yellow lava is the hottest, ranging in temperature from roughly 1,800 to 2,100 degrees Fahrenheit. Orange is cooler at roughly 1,500 to 1,800 degrees. And red lava is the coolest at about 1,100 to 1,472 degrees. Lava solidifies and turns black as it cools, but it retains heat for and doesn’t fully harden for days. Plus, magma, which is the molten rock under the surface, may continue to flow beneath surface, so keep off!

Lava Rocks

Solid lava is known as igneous rock. There are two types of igneous rock: plutonic and volcanic. Magma that cools and solidifies underground forms into plutonic rocks.

You’ve probably encountered volcanic rock even if you live thousands of miles from an active volcano. For example, you can thank a volcano for your granite countertops and for the pumice stone used to smooth rough edges of body parts from feet to teeth (ground to a powder as part of professional-grade tooth polish).

The exact type of igneous rock formed from magma or lava depends on its mineral content as well as the type of cooling process it went through. For example, glassy (and typically black) obsidian rock indicates a relatively quick cooling and hardening period. This process can still last for weeks, or even months, in the case of thicker pools of lava.

The spongy look of pumice is the result of gases trapped in the lava as it cooled. Because of these gas pockets, pumice is not very dense. In fact, it floats on water.

Study Up

Geology, the study of rocks, is one route to learning more about volcanoes. Other science careers related to volcanoes include, obviously, volcanology, which is a subset of geology, as is the study of plate tectonics, the investigation of the motion of the large plates that make up Earth’s upper crust. Seismology, the study of earthquakes, is another important route because of the relationship between the two natural events. And of course, mathematicians and computer scientists can help develop computer models that better help us understand and even predict earthquakes.

I know that a vinegar and baking soda volcano model is a science fair classic, but curious young minds can go beyond that. They’ll want to if they hope to one day earn the title of America's Top Young Scientist.