The past several weeks have been full of suspense and emotion for residents of the lower Puna District. Rather than being restful, recent weekends have been busy with notable events. On Oct. 25, lava crossed Cemetery Road/Apaa Street on the outskirts of Pahoa. On Nov. 9, a new lobe widened the flow along the road, entered private property and threatened an evacuated home. Just before noon the next day, the house was consumed by fire, the first residential structure taken by the June 27 lava flow.
The Pahoa community has been in a heightened state of alert for months, following a U.S. Geological Survey news release on Aug. 22 announcing the potential hazards posed by the advancing lava flow. Emergency proclamations by the Hawaii County mayor and state governor followed in early September, paving the way for a federal disaster declaration by President Barack Obama in early November. This declaration allows local government and qualified nonprofit organizations to access federal funds to help address emergency protective measures and hazard mitigation.
The most obvious hazard is flowing lava. The loss of property and services, associated fires and threat to community safety by the flow are primary concerns for emergency managers. The lava advance rate has been variable, ranging from negligible to nearly a quarter mile in a day. Planning for evacuations, alternate roads and continuity of utilities and services becomes more difficult with the inconsistent timing of the lava’s progress.
Currently, the flow is encroaching on residential areas and burning forests, pastures, roads and other man-made structures and debris. The dense plume, which is frequently visible, is a mixture of volcanic and nonvolcanic gases and particles. Although a less overt hazard, poor air quality downwind of the active lava flow can present challenges for some individuals.
Sulfur dioxide gas, the main contributor to Hawaii’s volcanic air pollution, or vog, is primarily released from actively degassing vents at Kilauea Volcano’s summit (Halemaumau) and East Rift Zone (Puu Oo). However, a small amount of this pungent gas is also released from flowing lava. Individuals with pre-existing respiratory conditions, such as asthma, could be impacted by the low levels of sulfur dioxide if they are immediately adjacent to an active lava flow.
When lava comes into contact with vegetation, burning plant material produces a complex mixture that includes carbon dioxide and carbon monoxide gas, as well as various particulates. Vegetation can decompose in the hot environment beneath the surface of the lava, generating gases that can ignite and explode when confined in underground pockets. These explosions occur frequently around the June 27 lava flow.
The burning of manmade features, such as paved roads, creates toxic fumes. In the short-term, molten asphalt fumes can cause eye and respiratory tract irritation. The Occupational Safety and Health Administration notes that workers exposed to asphalt fumes are at risk of developing headaches, rashes, coughing and possibly cancer.
If the June 27 flow continues its forward progress, lava could eventually reach the Pacific Ocean. If this happens, molten lava will react vigorously with the cold seawater, creating a large steam plume laden with hydrochloric acid. A 1990 study by the National Institute of Occupational Safety and Health showed that near-shore hydrochloric acid concentration decreased tenfold over a distance of less than half a mile, so areas immediately downwind of an ocean entry would likely be most impacted.
The hazards associated with gases and particles generated by flowing lava depend on the flow’s proximity, the items burned and how the wind directs and disperses the resulting pollutants. Individuals with pre-existing respiratory conditions are the most impacted by air quality hazards, and are advised to limit their exposures and monitor their responses closely.
Information on air quality impacts and health recommendations are available through the Hawaii County at hawaiicounty.gov/lava-related, the state Department of Health at health.hawaii.gov and the American Lung Association’s free helpline at (800) LUNGUSA. A wildfire smoke guide is available at arb.ca.gov. Information on local wind conditions is posted at weather.hawaii.edu and under “local graphics” at prh.noaa.gov/hnl/pages.
Puna residents are encouraged to stay informed about the progress of the June 27 lava flow. Daily updates are posted by the Hawaiian Volcano Observatory and Hawaii County Civil Defense at hvo.wr.usgs.gov and hawaiicounty.gov/active-alerts.
Kilauea activity update
The June 27 lava flow from Puu Oo remained active on iīlauea Volcano’s East Rift Zone. Breakouts were active high on the flow field, about 4 miles downslope from Puu Oo, but most were scattered across the flow field from near the Pahoa Japanese Cemetery to about 2 miles upslope from Apaa Street. On Monday, one of these breakouts crossed Apaa Street near the Pahoa Transfer Station and destroyed one house. Lava also encroached on the south edge of the transfer station property and on Thursday, another breakout was active about 300 yards farther west. There was no significant change in activity at Puu Oo.
The summit lava lake within Halemaumau Crater produced nighttime glow that was visible via HVO’s webcam over the past week. The lava level generally rose, except for a brief drop Wednesday, matching the trend in ground tilt and reflecting the occurrence of the most recent deflation-inflation event. As of this writing on Thursday, the lava lake was about 170 feet below the rim of the Overlook crater.
There were three earthquakes reported felt on Hawaii Island during the past week. At 7:45 p.m. Nov. 8, a magnitude-2.4 earthquake occurred 2 miles southeast of Captain Cook at a depth of 7 miles. At 11:53 a.m. Nov. 9, a magnitude-2.6 earthquake occurred 4 miles south of Puu Oo at a depth of 4 miles, at 5:39 a.m. Monday, a magnitude-3.8 earthquake occurred 9 miles northwest of Kailua at a depth of 7 miles.
Visit the HVO website at hvo.wr.usgs.gov for past Volcano Watch articles and current Kilauea, Mauna Loa and Hualalai activity updates, recent volcano photos, recent earthquakes and more; call 967-8862 for a Kilauea summary; email questions to askhvo@usgs.gov.