While there is no eruption at Kilauea on the Big Island of Hawaii right now, a sudden increase in earthquake activity there may indicate one can happen soon. Due to that threat, the Hawaiian Volcano Observatory (HVO) unit from USGS has informed the public they will return to issuing daily updates until an eruption occurs or seismicity wanes. HVO is maintaining alert levels and aviation codes; the alert level remains ADVISORY while the aviation color code remains YELLOW. Additionally, Hawaii Volcanoes National Park, where much of Kilauea Volcano and its summit caldera reside, has closed some roadways, parking lots, and trails in the park due to these potential threats.
According to USGS, the area just south of Kilauea’s summit is currently showing signs of elevated unrest. No other unusual activity has been noted along Kilauea’s East Rift Zone or Southwest Rift Zone. Inflationary tilt is continuing at a slightly slower rate in the area just south of the summit caldera. Inflation at the summit of Kilauea remains close to its highest level in over 5 years and has nearly returned to the level seen just before the last eruption on September 10th. Seismicity beneath the Kilauea summit region, which began October 4, increased with about 320 earthquakes striking in the last 24 hours. Most of the earthquakes are from the ongoing seismic swarm in a region south of the caldera at depths of around 1.5–2 miles below the surface. According to HVO, the trend of the seismic activity parallels, but is slightly south of the December 1974 eruption vents. Yesterday, from 3-6 AM, strong seismicity was recorded at the northeast end of this trend at the southern boundary of the caldera. Seismicity in the area decreased around 6 AM but still remains elevated.
Measurements from continuous gas monitoring stations downwind of Puʻuʻōʻō in the middle East Rift Zone—the site of 1983–2018 eruptive activity—remain below detection limits for SO2, indicating that SO2 emissions from Puʻuʻōʻō are negligible. Sulfur dioxide (SO2) emission rates remain low and were measured at a rate of about 150 tonnes per day on September 25.
While gas levels remain low for now, levels of volcanic gas (sulfur dioxide and carbon dioxide) can remain locally hazardous even though Kilauea isn’t yet erupting. HVO cautions, saying that while sulfur dioxide (SO2) gas emissions have greatly decreased, local concentrations of sulfur dioxide (SO2) or hydrogen sulfide (H2S) may persist in downwind areas, and residents may notice odors of these gases occasionally.
“Significant hazards also remain around Halemaʻumaʻu from crater wall instability, ground cracking, and rockfalls that can be enhanced by earthquakes within the area closed to the public,” the USGS warns.
With an increasing threat level at the volcano, the National Park Service has taken action to prevent visitors from entering in areas of greatest potential danger. “Hawaiʻi Volcanoes National Park is closely monitoring Kīlauea in collaboration with our colleagues at the USGS Hawaiian Volcano Observatory. The park is currently open, but visitors should be prepared and stay informed,” said the park service in an update posted online. Hilina Pali Road from Chain of Craters Road to Hilina Pali Overlook are now closed. The Pu’upua’i parking lot, Pu’upua’i Overlook, and the trail that connects it to Devestation Trail, including the Devastation Trail parking lot, are also closed. The Keanakako’i Overlook, the paved trail to/from Chain of Craters Road, and the nearby Crater Rim Trail are also closed as is the Maunaiki and Ka’u Desert Trails. The Kulanaokuaiki Campground has also been closed. The Visitors Center along with multiple viewing sites into the summit caldera crater remain open at the park.
This surge of activity at the volcano is occurring just weeks after another eruption at the summit ended. Back on September 16, HVO declared the eruption over. With the eruption over, the amount of volcanic gas spewing into the air was also significantly reduced, helping clear the air of many communities on the island which had harmful levels of volcanic-induced air pollution. On September 10, Kilauea exploded to life after an intense swarm of earthquakes near the summit. The lava put on quite the show for visitors who were able to safely observe the eruption inside the volcano caldera from above it at Hawaii Volcanoes National Park. The lava from that eruption never left the summit caldera.
The significant volcanic gas emissions were very noticeable in Hawaii in the days after the September eruption, especially on the west coast of the island where winds helped carry bring the volcanic emissions to, but relaxed to leave them there. Purple Air sensors on the island showed high air pollution levels, but with the eruption now over, the levels have returned to a cleaner normal.
Sulfur dioxide affects human health when it is breathed in. It irritates the nose, throat, and airways to cause coughing, wheezing, shortness of breath, or a tight feeling around the chest. The effects of sulfur dioxide are felt very quickly and most people would feel the worst symptoms in 10 or 15 minutes after breathing it in. Those most at risk of developing problems if they are exposed to sulfur dioxide are people with asthma or similar conditions. Extreme concentrations of sulfur dioxide can be deadly if inhaled. When combined with other substances additional hazards can be created; as an example, rain falling through a sulfur dioxide plume could produce an acid rainfall. Sulfur dioxide is invisible to the human eye, but when it reacts with other gases, aerosol particles can form to cause haze, and according to NASA in extreme widespread events, climate cooling.
During the May 2018 eruption of Hawaii’s Kilauea Volcano’s Lower East Rift Zone, sulfur dioxide was covering the surface in a residential neighborhood from erupting fissures. During that eruption, a plume of sulfur dioxide was detected by the Ozone Mapper Profiler Suite (OMPS) on the Suomi-NPP satellite. During the height of that eruption during the spring and summer of 2018, authorities evacuated people from the danger sulfur dioxide posed. “Hawaii Fire Department reports extremely dangerous conditions due to high levels of Sulfur Dioxide gas in the evacuation area. Elderly, young, and people with compromised respiratory systems are especially vulnerable,” warned the Hawaii County Civil Defense in 2018. They added, “The high levels detected are an immediate threat to life for all who become exposed. First responders may not be able to come to the aid of residents who refuse to evacuate. ”
But with the location of the September eruption contained to the caldera and wind patterns steering pollutants around the south side of the island to the west side, there wasn’t that same harmful concentration that was seen in 2018.
AVO is responsible for issuing Aviation Codes and Volcanic Activity Alert Levels. Aviation Codes are green, yellow, orange, or red. When ground-based instrumentation is insufficient to establish that a volcano is at a typical background level of activity, it is simply “unassigned.” While green means typical activity associated with a non-eruptive state, yellow means a volcano is exhibiting signs of elevated unrest above known background levels. When a volcano exhibits heightened or escalating unrest with the increased potential of eruption, it jumps to orange. Finally, when an eruption is imminent with significant emission of volcanic ash expected in the atmosphere or an eruption is underway with significant emission of volcanic ash into the atmosphere, the code becomes red. Volcanic Activity Alert levels are normal, advisory, watch, or warning. As with aviation codes, if data is insufficient, it is simply labeled as “unassigned.” When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano exhibits signs of elevated unrest above background level, an advisory is issued. If a volcano exhibits heightened or escalating unrest, a watch is issued while a warning is issued when a hazardous eruption is imminent.
HVO is also monitoring the Mauna Loa and Hualalai Volcanoes on the Big Island of Hawaii. At this time, both are at a NORMAL alert level and a GREEN aviation color code with no unusual activity detected or observed at either.