Eruption Information

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Hazards Associated with the Ongoing Eruption

Lava Fountains and Tephrafall

Lava fountains during eruptive episodes have reached up to 1570 feet (479 meters) above the vents. Material from the lava fountains, called tephra, is deposited near the vents and finer particles can be transported downwind. 

Tephra is a word for any volcanic material that is erupted and travels through the air before landing on the ground. Tephra includes very small particles, such as volcanic ash, as well as light and frothy rocks full of holes called reticulite, more robust rocks like scoria, larger pieces called bombs, and ever-present strands of volcanic glass known as Pele’s Hair. 

Most of the tephra has been deposited southwest of the active vents, in a closed area of Hawaiʻi Volcanoes National Park, A mound of tephra over 150 feet (45 meters) high has grown on the crater rim, and a blanket of tephra extends over a mile (2 km) to the southwest. Occasionally, tephra can fall on populated areas nearby or downwind. 

Residents and visitors should minimize exposure to Pele's hair and other glassy volcanic fragments, which can cause skin and eye irritation and can also contaminate catchment water supplies. More information about how Pele's hair, its hazards, and what to do is available here. A recently updated Frequently Asked Questions document that includes information about potential health effects of Pele's hair is available here: https://vog.ivhhn.org/sites/default/files/PelesHair_FAQs_v2.pdf 

Lava flows have been confined to the floor of Halemaʻumaʻu crater within Kaluapele (Kīlauea summit caldera). This area of Hawaiʻi Volcanoes National Park is closed to the public. 

Types of Tephra

Volcanic Gas Emissions

Large amounts of volcanic gas—primarily water vapor (H₂O), carbon dioxide (CO₂), and sulfur dioxide (SO₂)—are released during lava fountaining episodes at the summit of the Kīlauea. Episodes in the ongoing eruption have produced emission rates up to 75,000 tonnes per day of SO₂. It’s likely that sulfur dioxide emission rates have been even higher during some eruptive episodes, though measurements have not been possible. When the lava fountains are not active, SO₂ emission rates are decreased and in the range of 1,200 to 1,500 tonnes per day. 

The plume of volcanic gas and fine tephra particles rising from the vents has reached more than 20,000 feet (6,000 m) above ground level and is transported by the wind.  SO₂ reacts in the atmosphere with oxygen, sunlight, moisture, and other gases and particles, and within hours to days, converts to fine particles. The particles scatter sunlight and cause the visible haze that is observed downwind of Kīlauea, known as vog (volcanic smog). Vog creates the potential for airborne health hazards to residents and visitors, damages agricultural crops and other plants, and affects livestock operations.

Further information on vog can be found at https://vog.ivhhn.org/

Wind Conditions Affect Distribution of VOG and Tephra Fall

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In Hawaii, trade winds refer to the predominant condition of winds that flow from the northeast to the southwest. Where rising warm air from the Earthʻs surface meets the trade winds, an inversion layer exists between 5,000-10,000 feet (1,500-3,000 m) elevation. The inversion inhibits air below from rising above the summits of Mauna Kea and Mauna Loa and causes air to flow around the mountains. 

Eruptive plumes at the summit of Kīlauea can rise vertically and be sheared to the southwest where they encounter the trade wind inversion. During trade wind conditions, most volcanic gas and tephra is transported to the southwest. Larger tephra particles fall on the ground within 1-3 miles (1-5 kilometers) of the eruptive vent(s), with the highest concentrations immediately downwind of the vent(s) in the closed area of Hawaiʻi Volcanoes National Park. Light particles, including Pele's hair, can be transported greater distances, 10 miles (15 kilometers) from the vent downwind.

During less common Kona wind conditions, material from Kīlauea summit eruptive plumes may be transported north/west. Slack wind conditions allow eruptive plumes at the summit of Kīlauea to rise buoyantly and billow outwards. 

The subtropical jet stream can be at elevations above 10,000 feet (3,000 m) and consist of generally faster winds travelling from west/northwest to east/southeast. The volcanic plumes during the ongoing Kīlauea summit eruption have not encountered the subtropical jet stream.  

How to Stay Aware of Eruptive Activity and Hazards

• Read the latest Kīlauea - Volcano Update for information on the status of the eruption
• Check the Hawaiʻi Volcanoes National Park website for information about viewing and closures
• Follow official guidelines; information on potential impacts will come from the Hawaii County Civil Defense Agency

Impacts of Recent Eruptive Episodes

Several lava fountaining episodes have resulted in tephra fall on visitor areas of Hawaiʻi Volcanoes National Park, Highway 11 north of the vents, and neighboring communities.  Where tephra falls is dependent on the eruptive episode (how high the lava fountains reach) and wind conditions (where the wind is blowing and how strongly). 

Additional Information

• Search for past volcano updates
• Subscribe to the USGS Volcano Notification Service to receive eruption updates
• Kīlauea geology and history
• Kīlauea Maps
• Vog Information Dashboard
• General Hawai‘i County Civil Defense information or subscribe to CD alerts and updates
• Follow USGS Volcanoes on Twitter, Facebook, and Instagram.
• Volcano viewing information from Hawaii Volcanoes National Park

Recent eruptions have taken place within Hawai‘i Volcanoes National Park. Please visit the Park website to learn more about their operations.