#USGS Volcano Alert

Damage classification included all types of structures, including homes, water tanks and other farming or industrial buildings. Inundating 14 square miles (35.5 square km) of land, Kīlauea’s 2018 lava flows destroyed 1,839 and damaged 90 structures in total. These are the highest recorded numbers of impacted structures from a lava flow event in Hawaiʻi and one of the highest globally. 

The ongoing eruption at the summit of Kīlauea hasn’t made the news recently, but that doesn’t mean the recent eruptive activity hasn’t been noteworthy.  It’s just been operating quietly in the background, without much fanfare.

In one dictionary definition, a volcano is a vent in the earth’s crust through which rock or lava is ejected. In another, a volcano is a cone-shaped hill or mountain built around a vent. Most volcanologists find both of these dictionary definitions somewhat lacking.

HVO, in collaboration with the University of Hawai’i at Mānoa, will begin an investigation this summer to learn more about the nature of these frequent, deep earthquakes beneath the southern part of the Island of Hawaiʻi.

Disturbances to a magma or lava body—such as Kīlauea Volcano’s underground summit magma reservoir or its current lava lake—can occur for a variety of reasons, including rising gas pockets or the fall of wall rocks into a lava lake. When a body of magma or lava is disturbed, the fluid in it can respond by vibrating or sloshing in a variety of ways.

The long-term likelihood of an area being invaded by lava in the future, is estimated in two different ways based on the history of lava flow activity. One approach uses a geologic map to calculate how much land surface was covered by lava during different periods going back into the past; the resulting numbers are called coverage rates. Another approach calculates how frequently lava flows have occurred within specific areas over time; the resulting number is a lava flow probability.

What are symptoms leading up to an eruption? The main player in monitoring volcanoes is seismicity—the frequency and magnitude of earthquakes.  When magma enters the volcanic edifice, it accumulates and makes space for itself by compressing many tiny void spaces.  Continued filling by magma creates pressure on the walls of reservoirs, causing slip, faults, or cracking in the surrounding brittle rock.  All these motions result in the generation of earthquakes. 

The word ‘radar’ recalls images of a meteorologist forecasting weather, or aircraft blips on a green radar display, as frequently portrayed in the movies. RADAR is an acronym for Radio Detection And Ranging, a tool that has been broadly used since its conception in the early 1900s.

The June 1, 2021, USGS Hawaiian Volcano Observatory (HVO) Kīlauea weekly update summary reads: “Kīlauea Volcano is no longer erupting. No surface activity has been observed…It is possible that the Halema‘uma‘u vent could resume eruption or that Kīlauea is entering a period of quiescence prior to the next eruption.”

One of the most interesting aspects of the current activity in Halemaʻumaʻu is the occasional oozing of lava around the edges of the entire crater while the lava surface is rising. Has that phenomenon been reported before in any accounts of previous Kīlauea activity?

Pele returned to the summit of Kīlauea on the evening of Dec. 20, 2020. Incredible video documents the start of the new eruption in Halema‘uma‘u and the dynamic ongoing activity. There was no significant change that suggested lava would erupt again so rapidly, but there were subtle signs of restless behavior around Kīlauea’s summit in the months prior to the eruption.

“When will Mauna Loa erupt next?” This was the title of a Volcano Awareness Month video presentation released by the USGS Hawaiian Volcano Observatory in January 2021. This was also the topic of discussion among HVO scientists last week following the detection of slight changes in ground deformation and seismicity at the summit of Mauna Loa.

Words matter in volcanology just as in the rest of society. Words matter among volcanologists themselves, of course, but they particularly matter in our dealings with the public, when we attempt to both tell what is happening and educate about how volcanoes work. Accuracy of words promotes understanding and clarity of thought and is essential to both telling and educating.

In addition to a new year and a new eruption, the USGS Hawaiian Volcano Observatory is ushering in a new era for processing and studying volcanic samples.

This is why the MMI scale is the best way to communicate the relative effects among earthquakes. Values are derived from direct observations of the public and will give the best sense of shaking experienced in different regions.

Kīlauea monitoring data for the past month show variable but typical rates of seismicity and ground deformation, low rates of sulfur dioxide emissions, and only minor geologic changes since the end of eruptive activity in September 2018.