As winter approaches, many Hawaii Island residents eagerly await the appearance of sub-tropical snow atop Mauna Kea and Mauna Loa. Another common occurrence on Hawaii Island during winter months is the frequent interruption of the steady northeasterly trade winds. These winds, or the lack of them, play a leading role in determining where volcanic air pollution from Kilauea, known as vog, is distributed across the island, and sometimes the state.
As winter approaches, many Hawaii Island residents eagerly await the appearance of sub-tropical snow atop Mauna Kea and Mauna Loa. Another common occurrence on Hawaii Island during winter months is the frequent interruption of the steady northeasterly trade winds. These winds, or the lack of them, play a leading role in determining where volcanic air pollution from Kilauea, known as vog, is distributed across the island, and sometimes the state.
Vog, caused by sulfur dioxide gas (SO2) emitted from Kilauea, has been a frequent problem on Hawaii Island for the past 30 years. Since the onset of the summit eruption in 2008, there has been a dramatic increase in the amount of SO2 and other gases released from the volcano and in the damaging effects of vog on the island.
From May to September, trade winds blow 80-95 percent of the time, but from October to April, the frequency drops to 50-80 percent. On Hawaii Island, the districts of Ka‘u and Kona bear the brunt of vog during northeasterly trade winds. But when trade winds are absent, areas impacted by vog can include East Hawaii, the whole island of Hawaii, and, at times, the entire state.
For this winter’s vog season, new resources are available to help people become familiar with, and minimize their exposure to, vog.
A new internet-based “Hawaii Interagency Vog Information Dashboard” (ivhhn.org/vog) provides a user-friendly starting point to search for information about vog. Topics on this dashboard include vog forecasts, real-time vog concentrations, health effects and environmental impacts of vog, and how people can protect themselves from vog, as well as links to published scientific literature.
The dashboard also leads users to a new suite of concise vog information products. These products, which include a booklet of frequently asked questions and a brochure and poster on protecting yourself from vog, are available online (ivhhn.org/vog/vog-fact-sheets), where they can be viewed or downloaded.
Print copies of these vog information products are available through the state Department of Health District offices. They are also in the process of being distributed to public libraries and schools around the Island of Hawaii.
If you’re interested in how your neighbors cope with vog, check out these new products, as they incorporate information and protection strategies gathered through community surveys in 2015. The surveys, which were conducted by an international researcher in cooperation with the USGS Hawaiian Volcano Observatory, examined the strategies used by Hawaii Island residents who live with vog, and how those people would like to receive information and guidance about vog.
If you’d like to know when vog might be in your area, a dashboard link takes you to “vog and wind forecasts,” which includes the University of Hawaii at Manoa “Vog Measurement and Prediction Project” (weather.hawaii.edu/vmap/). This vog model provides an animated two-day forecast of SO2 gas and sulfate particle concentrations for the State of Hawaii. Many people find this forecast useful for planning outdoor activities to minimize their exposure to vog.
As SO2 travels away from Kilauea Volcano’s eruptive vents, it is gradually converted (through chemical reactions in the atmosphere) from a gas to solid particles and liquid droplets. So, in areas close to the vent, SO2 gas is a component of the vog. But in areas distant from Kilauea, like West Hawaii or on other Hawaiian islands, vog is composed of particles, with virtually no SO2 gas in the mix.
The Department of Health “Hawaii ShortTerm SO2 Advisory” (https://hiso2index.info/), which provides data on current SO2 gas levels, is extremely helpful for areas close to Kilauea. But for West Hawaii (Kona) residents, the more relevant particle information is available through the vog dashboard link to “AirNow particle data” (ivhhn.org/vog/current-air-quality).
Gas emissions from Kilauea have decreased somewhat since the summit eruption began in 2008, but vog continues to challenge Hawaii communities, causing impacts to health, agriculture, and infrastructure. Learning how to identify when vog is in your area, and how to protect yourself and your family when necessary, are adaptations to living with the remarkable volcano in our backyard.
Hopefully, the new information products and online dashboard will help Hawaii residents to understand and adopt strategies for living more comfortably with vog.
Volcano Watch is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.
Volcano Activity Updates
Kilauea continues to erupt at its summit and East Rift Zone. This past week, the summit lava lake level varied from about 62 feet) to about 13 feet below the vent rim. The 61g lava flow continued to enter the ocean near Kamokuna, and does not pose an immediate threat to nearby communities.
Mauna Loa is not erupting. During the past week, earthquakes occurred primarily at the summit and upper Southwest Rift Zone at depths less than 3 miles, with several others occurring at depths greater than 25 miles. Additional earthquakes occurred in the Kaoiki area of the east flank between Kilauea and Mauna Loa mostly in the 3-7-mile depth range. Deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone continued, with inflation occurring mainly in the southwestern part of the magma storage complex.
Two earthquakes were reported felt on Hawaii Island this past week. At 5:48 a.m. Nov. 4, a magnitude-3.5 earthquake occurred 6.4 miles east of Honaunau at a depth of 7.4 miles. At 7:24 a.m. Nov. 5, a magnitude-2.7 earthquake occurred 7.1 miles northwest of Kailua-Kona at a depth of 4.5 miles.
Visit the HVO website (https://hvo.wr.usgs.gov) for past Volcano Watch articles, Kilauea daily eruption updates, Mauna Loa weekly updates, volcano photos, recent earthquakes info, and more; call for summary updates at 967-8862 (Kilauea) or 967-8866 (Mauna Loa); email questions to askHVO@usgs.gov.