Volcano Watch: Kīlauea Volcano – What’s new and what’s not

An aerial view of Halema‘uma‘u at the summit of Kīlauea Volcano captured from an Unmanned Aircraft Systems (UAS) overflight video on May 31, 2018. Limited UAS flights into this hazardous area are conducted with permission and coordination with Hawaiʻi Volcanoes National Park to collect visual information on this changing eruption site. Scientists will examine the video footage in detail to understand the evolution of the expanding collapse area and assess hazards at Kīlauea’s summit. Credit: U.S. Department of the Interior, Office of Aviation Services, and the U.S. Geological Survey.

An aerial view of Halema‘uma‘u at the summit of Kīlauea Volcano captured from an Unmanned Aircraft Systems (UAS) overflight video on May 31, 2018. Limited UAS flights into this hazardous area are conducted with permission and coordination with Hawaiʻi Volcanoes National Park to collect visual information on this changing eruption site. Scientists will examine the video footage in detail to understand the evolution of the expanding collapse area and assess hazards at Kīlauea’s summit. Credit: U.S. Department of the Interior, Office of Aviation Services, and the U.S. Geological Survey.

(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

With the current activity at the volcano’s lower East Rift Zone and summit, it’s an understatement to say that Kīlauea has been making worldwide headlines the past month.

To the uninitiated, the scientific and colloquial terms that are used to describe eruptive processes and products at Hawaiian volcanoes might seem unusual or scary, when, in fact, they describe what’s been happening at Kīlauea for more than three decades. So, today we address Kīlauea’s current activity—what’s new and what’s not—starting with the two eruption sites: East Rift Zone and summit.

Kīlauea Volcano’s East Rift Zone has been erupting nearly non-stop since 1983, with an eruption on the volcano’s middle East Rift Zone—generally referred to as the Puʻu ʻŌʻō eruption. (Puʻu ʻŌʻō is the volcanic cone built from the accumulation of cinder and spatter falling from episodic high lava fountains during the eruption’s first three years.)

For 35-plus years, lava erupting from vents on or near Puʻu ʻŌʻō created surface flows that advanced down the south flank of Kīlauea. This changed on April 30, 2018, when magma from the middle East Rift Zone intruded into the lower part of the rift zone. This intrusion of magma ultimately resulted in the fissure vents now erupting in Hawaiʻi Island’s lower Puna District. So, while an East Rift Zone eruption is not new, the location of the current vents (or fissures) is different from past vents.

Kīlauea’s summit eruption began in March 2008, when a vent opened in Halema‘uma‘u, a crater within the volcano’s summit caldera. For over 10 years, this vent was the site of a lava lake that rose and fell—sometimes fluctuating as much as 30 m (100 ft) in a 24-hour period—in concert with summit inflation and deflation. Throughout that time, rocks falling from the steep vent walls triggered numerous small gas-driven explosions that often blasted molten lava and pieces of older rock onto the rim of Halema‘uma‘u and adjacent caldera floor.

In early May 2018, in response to East Rift Zone changes, the summit lava lake dropped 100s of meters (yards) and completely out of view. Concern grew that magma feeding the lava lake could drop below the water table, allowing groundwater to enter the system, which could cause steam-driven explosions. So, while small summit explosions are not new, the mechanism, vigor, plume heights, and extent of ash fallout from the current explosive activity are.

We’ll now address what’s new—or not—with volcanic products and processes on Kīlauea.

Sulfur dioxide: When a new eruptive vent opens on Kīlauea, sulfur dioxide emissions increase—sometimes dramatically—as happened with the opening of the summit vent in 2008, the Kamoamoa fissure eruption in 2011, and now, with the lower East Rift Zone fissure eruption. Sulfur dioxide is one of the three most abundant gases released during any volcanic eruption (the other two being water vapor and carbon dioxide), and it has been emitted in large quantities since the start of the Puʻu ʻŌʻō eruption in 1983. More info: vog.ivhhn.org/leilani-eruption.

Vog: Sulfur dioxide reacts with oxygen, sunlight, moisture, and other gases and particles in the atmosphere to create a visible haze known as vog (volcanic air pollution), which has been an ongoing issue in Hawaiʻi since 1983, as well as during all previous eruptions of Kīlauea (and Mauna Loa). Increased sulfur dioxide emissions can result in more widespread and intense vog. Impacts depend on wind direction and your location—whether or not you’re downwind of the vog source—as well as your individual sensitivity. More info: pubs.usgs.gov/fs/2017/3017/fs2… and vog.ivhhn.org/.

Laze: Since 1983, lava flows erupted from Kīlauea have reached the ocean about half the time. The interaction of hot lava and cool seawater forms a white plume known as “laze” (lava haze), which is composed of condensed seawater steam, hydrochloric acid gas, and tiny shards of volcanic glass. This corrosive mixture can irritate lungs, eyes, and skin, but its effects diminish rapidly with distance from the ocean entry.

Ash: Small amounts of ash, which is carried by wind, have erupted from Kīlauea’s summit vent since it opened in 2008. Where ash falls depends on the wind direction. With recent changes at the summit, vigorous explosions have occurred more frequently at Halema‘uma‘u, resulting in higher, ash-laden plumes that can be blown far downwind. More info: volcanoes.usgs.gov/observatori… and vog.ivhhn.org/summit-ash-hazar….

Pele’s hair: Thin strands of volcanic glass, called “Pele’s hair” after the goddess of Hawaiian volcanoes, form when lava is thrown into the air or stretched into filaments (like pulling taffy). Throughout Kīlauea’s history, erupting lava fountains and lava lakes have produced Pele’s hair, which can be blown far downwind.

With Kīlauea, as with so much else, the more things change, the more they stay the same.

This animated GIF shows a pair of radar amplitude images that were acquired by the Italian Space Agency's Cosmo-SkyMed satellite system. The images illustrate changes to the caldera area of Kīlauea Volcano that occurred between May 23 at 6:00 p.m. HST and May 31 at 6:00 p.m. HST. The satellite transmits a radar signal at the surface and measures the strength of the return, with bright areas indicating a strong return and dark areas a weak return. Strong returns indicate rough surfaces or slopes that point back at the radar, while weak returns come from smooth surfaces or slopes angled away from the radar. The expansion of the summit eruptive vent within Halema‘uma‘u crater is clear, but differences between the images also indicate widening of Halema‘uma‘u itself, especially along the crater's southeast edge. These changes are a consequence of rockfall into the growing summit eruptive vent, which is floored by rubble.

This animated GIF shows a pair of radar amplitude images that were acquired by the Italian Space Agency’s Cosmo-SkyMed satellite system. The images illustrate changes to the caldera area of Kīlauea Volcano that occurred between May 23 at 6:00 p.m. HST and May 31 at 6:00 p.m. HST. The satellite transmits a radar signal at the surface and measures the strength of the return, with bright areas indicating a strong return and dark areas a weak return. Strong returns indicate rough surfaces or slopes that point back at the radar, while weak returns come from smooth surfaces or slopes angled away from the radar. The expansion of the summit eruptive vent within Halema‘uma‘u crater is clear, but differences between the images also indicate widening of Halema‘uma‘u itself, especially along the crater’s southeast edge. These changes are a consequence of rockfall into the growing summit eruptive vent, which is floored by rubble.

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