Eruptive fissures in Hawaii associated with Kilauea

Kilauea’s Eruptive Fissures: When Hawaii’s Volcanoes Crack Open

Kīlauea. Just the name conjures images of fiery landscapes and molten rock. This active shield volcano, nestled on the southeastern coast of Hawai’i Island, isn’t just any volcano; it’s one of the most restless and studied volcanoes on the planet. And when Kīlauea gets active, things get really interesting, especially when it comes to its eruptive fissures.

So, what exactly are these fissures? Think of them as cracks in the Earth’s surface, nature’s way of releasing pent-up pressure. These aren’t just any cracks, though. They’re pathways for lava, gas, and intense heat to escape from deep within the volcano.

How Fissures Form: A Volcanic Pressure Cooker

These fissures love to pop up along Kīlauea’s rift zones. These zones are basically weak spots in the volcano’s structure, like fault lines in a geological sense. They act as highways, guiding magma from the volcano’s summit reservoir towards the surface. Before a fissure eruption, things start to get a little shaky – literally. We see increased earthquake activity and the ground starts to bulge and deform, all signs that magma is on the move beneath our feet. As this molten rock pushes its way into the rift zone, it puts immense pressure on the surrounding rocks, eventually causing them to fracture and split open, creating those dramatic fissures.

The Big One: The 2018 Lower East Rift Zone Eruption

If you want to understand the sheer power of fissure eruptions, look no further than the 2018 eruption in Kīlauea’s Lower East Rift Zone (LERZ). I remember watching the news coverage at the time – it was both terrifying and awe-inspiring. It all started after the Puʻu ʻŌʻō crater floor collapsed on April 30, 2018. Magma then began its journey down the LERZ, and on May 3, the first fissure ripped open in the Leilani Estates subdivision. Can you imagine waking up to that?

Over the next few weeks, a total of 24 fissures appeared, stretching across a 6-kilometer-long zone. These weren’t just little cracks; they were unleashing rivers of lava that swallowed homes, roads, and everything else in their path. The landscape was being completely reshaped before our eyes.

Fissure 8 became the star of the show, in a way. It was like a geyser of lava, with fountains shooting up 60 meters into the air! This fiery display fed a massive lava flow that surged towards the ocean, eventually reaching Kapoho Bay on June 3. When the lava met the water, it created a brand-new lava delta, adding 3.5 square kilometers of land to the island. By the time the eruption finally subsided in August 2018, over 35 square kilometers of the lower Puna District were buried under lava. It was a stark reminder of nature’s raw power.

The Dark Side: Hazards of Fissure Eruptions

Fissure eruptions aren’t just a spectacle; they come with a whole host of dangers:

• Lava flows: The most obvious threat is being overrun by lava. It’s like a slow-motion bulldozer, unstoppable and incredibly destructive.
• Volcanic gases: These eruptions release tons of nasty gases, especially sulfur dioxide (SO2). Breathing this stuff in isn’t good for you; it can cause all sorts of respiratory problems. Plus, SO2 reacts in the atmosphere to create vog (volcanic smog) and acid rain, which isn’t great for the environment either.
• Laze: When lava flows hit the ocean, they create this toxic plume called laze. It’s a mix of hydrochloric acid and volcanic glass particles, and it can irritate your skin, eyes, and lungs. Stay away from that stuff!
• Explosions: If magma comes into contact with groundwater, things can get really explosive. Think ash plumes, flying rocks – the whole works.
• Ground Cracking: The fissures themselves can cause the ground to become unstable, making it dangerous for buildings and infrastructure.

Keeping Watch: Monitoring and Research Efforts

The Hawaiian Volcano Observatory (HVO) is like the volcano’s personal doctor, constantly monitoring Kīlauea for any signs of trouble. They use all sorts of tools, from seismometers to track earthquakes to instruments that measure ground deformation and gas emissions. They’re also studying the lava itself, analyzing its composition and texture to understand what’s going on deep inside the volcano. It’s like forensic science, but for volcanoes!

Fissure 17: The Oddball

Out of all the fissures that have erupted at Kīlauea, Fissure 17, which was part of the 2018 LERZ eruption, was a bit of an anomaly. Most fissures erupt basaltic lava, but Fissure 17 produced andesitic lava, which has a higher silica content. It also had these explosive bursts of activity, called Strombolian eruptions, which were different from the more gentle eruptions seen at other fissures. Scientists believe that the magma from Fissure 17 might have mixed with older magma lurking within the rift zone. It just goes to show, volcanoes always have a few surprises up their sleeves.

What’s Happening Now?

Even after the dramatic 2018 eruption, Kīlauea hasn’t gone to sleep. In June 2024, we saw a new fissure eruption in Kīlauea’s Southwest Rift Zone. It didn’t last long, but it was a reminder that Kīlauea is still very much alive and kicking. As of July 2025, the volcano is being watched closely. Who knows what Kīlauea will do next? One thing’s for sure: this volcano will continue to keep us on our toes for years to come.