The last few weeks have seen remarkable changes to Kīlauea, the most active volcano in Hawaii (and possibly on Earth). The shield volcano that makes up much of the eastern shores of the Big Island has been erupting for the past 35 years, but starting in late April, something changed. Volcanologist aren’t sure why both the style and location of eruption transformed, but it has lead many who live and work on Kīlauea’s slopes and visit the Hawaii Volcanoes National Park to consider the volcano in a whole new light.
Kīlauea spans (on land) over 45 miles and looks like a warrior’s shield from above. From the central Halema’uma’u summit comes two rift zones that are the plumbing system of the volcano: the active East Rift Zone and the quiet Southwest Rift Zone.
{mosads}Since the mid-1980s, Kīlauea’s eruptions have been typified by lava flows and lava lakes. The volcano was home to not one but two lava lakes, persistent pools of roiling lava, at the Halema’uma’u summit crater and at another vent of lava on the East Rift zone called Pu’u O’o.
Lava flows have come from Pu’u O’o for decades, spilling down the volcano and travelling far in lava tubes, sometimes overrunning homes at Kalapana, Royal Gardens and Pahoa. In 2011, the Kamoamoa fissure eruption occurred between the summit and Pu’u O’o, but that was short lived and within the National Park.
Since earlier this spring, U.S. Geological Survey scientists at the Hawaiian Volcano Observatory had noticed that the volcano was inflating, both at Pu’u O’o and the summit. This typically means that magma is rising up from the source of Kīlauea’s molten rock over 60 miles beneath the volcano. The lava lake at the summit rose so high that it spilled over the top in late April, creating small lava flows.
Then, everything changed.
In early May, cracks in the ground and the smell of sulfur were noticed 15 miles to the east of Pu’u O’o in a subdivision called Leilani Estates, an area that hadn’t seen eruptions since the 1950’s and 1960’s.
Suddenly, the floor of Pu’u O’o collapsed, indicating that magma was draining out. HVO scientists thought that the magma was draining to somewhere in the lower East Rift zone near the new fissures. The pressure in the lower East Rift zone might soon send lava to the surface like water in a burst pipe.
Sure enough, lava started spattering from these fissures and lava flows covered the landscape. Since then, 22 fissures have opened, burying dozens of buildings and roads. The lava flows have reached the Pacific Ocean, slowly adding to the island’s shoreline.
At the same time as all this, the summit was seeing big changes as well. The lava lake that was spilling over in late April was now draining — and fast. In early May, the level of the lake was dropping 6 feet per-hour and is now over 900 feet from the rim of the crater. It has dropped so far that the lava is below the water table, so groundwater is turning to steam.
As rocks fall into this pit, they create a blockage and pressure builds. This leads to large explosions (especially for Kīlauea), some reaching 30,000 feet, throwing blocks of rocks for miles around the summit and spreading ash up to 20 miles from the volcano. These powerful explosions at the summit of Kīlauea haven’t occurred since 1924.
What is the impact of these dramatic changes at Kīlauea? Many people have lost their homes in Leilani Estates and Laipuna Gardens, where lava flows have buried and burned their property. Many times, this land can’t be resettled for years and instead of the lush forest, you are left with a barren landscape of black rock.
Infrastructure like roads and utilities need to be rebuilt as well, as the lava flows that tower 20 feet cover them. The future use of the Puna Geothermal Venture, a geothermal power plant on the lower East Rift zone is also in question as lava flows from the fissures are currently encroaching on the wells drilled for the project.
Depending on how long the summit explosions continue, the National Park and Volcano House will be closed to tourists. This disruption will impact the economy of the Big Island to the tune of millions of dollars, especially if the perception is that the entire island is unsafe. This is not true – most of the island, including the cities of Hilo and Kona, is unaffected by this new activity at Kīlauea.
There is no chance that the eruptions will trigger other volcanoes in Hawaii like Mauna Loa or cause a massive tsunami to strike. It is the areas where the lava flows, volcanic ash and potential volcanic fog (or “vog”) that should be avoided.
So far, only one injury has occurred during this eruption and this is a testament to the remarkable job the USGS geoscientists at the Hawaiian Volcano Observatory have done monitoring the events before and during the eruption.
Using data collected from the volcano (including earthquakes, gas emissions and inflation or deflation of the volcano using GPS stations), they were able to notice that an eruption could be in the works, its eventual location in the lower East Rift zone, the explosive behavior of the summit and the eastward march of the fissures towards the Puna Geothermal Venture. The cooperation between local emergency management and HVO has shown how volcanic disasters can be avoided with through science and planning.
No one is sure how long these new eruptions will continue. The area where the lava flows are erupting is still inflating and experiencing earthquakes, suggesting that magma is still moving to feed those fissures. As long as the summit lava lake stays far below its rim, we might expect large explosions to continue. Looking at eruptions in Kīlauea’s past, it would be a safe bet to think this eruption might last months before a “new normal” sets in at the volcano.
Erik Klemetti, Ph.D., is an associate professor and chairman of Geosciences at Denison University. He studies what happens inside volcanoes before, during and after eruption with projects at places like Mt. Hood in Oregon and Lassen Peak in California. He also writes Discover’s geology blog Rocky Planet about volcanic eruptions around the world. Follow him on Twitter at @eruptionsblog.