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Ash Fallout Hazard: Plumes as High as 20,000 Ft Possible

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Ash column rises from the Overlook crater at the summit of Kīlauea Volcano. HVO’s interpretation is that the explosion was triggered by a rockfall from the steep walls of Overlook crater. The photograph was taken at 8:29 a.m. HST on May 9, 2018 from the Jaggar Museum overlook. The explosion was short-lived. Geologists examining the ash deposits on the rim of Halema‘uma‘u crater found fresh lava fragments hurled from the lava lake. This explosion was not caused by the interaction of the lava lake with the water table. When the ash cleared from the crater about an hour after the explosion, geologists were able to observe the lava lake surface, which is still above the water table. PC: US Geological Survey

Halema’uma’u Ash Fallout Hazard:

The Hawaiian Volcano Observatory has cautioned about the possibility of an explosive eruption at Halemaʻumaʻu.

This is caused by the withdrawal of lava from Halemaʻumaʻu’s summit lake, which leads to a steam-driven eruption. Such an eruption could generate ash plumes as high as 20,000 feet. The area affected by ash plumes could be as wide as 12 miles.

Should this occur, the following are advised:

  • The danger from this eruption is ash fallout. The major response is to protect yourself from fallout.
  • If this event occurs while you are at home, stay indoors with the windows closed. Turn on your radio and listen for updates from authorities.
  • If you are in your car, keep the windows closed. Ash fallout may cause poor driving conditions, due to limited visibility and slippery driving conditions. Drive with extreme caution, or pull over and park.
  • After the hazard is passed, do check your home, and especially your catchment system, for any impact that may affect your water quality.

This is precautionary information for public safety in the event that there is a Halemaʻumaʻu explosive event.

At 9:17 a.m. HST, another weak ash plume rose from the Overlook Vent in Halema‘uma‘u crater, producing a slightly more energetic and darker plume. This second plume lacked the pink altered ash that was in the earlier plume, apparently consisting of more unaltered (therefore darker) rock fragments. This plume also was probably caused by rockfall into the deepening vent, not related to groundwater and steam-driven explosions. PC: US Geological Survey


What to do in case of Ash Fallout: (Information courtesy Hawaiʻi Emergency Management Agency)


Volcanic activity in Kīlauea crater could result in an explosion that sends an ash plume into the atmosphere. If you’re in the area, know what to do in case of an ashfall.

  • Close doors and windows.
  • Place damp towels at door thresholds and other draft sources. Tape windows.
  • Protect sensitive electronics and do not uncover until the environment is totally ash-free.
  • Disconnect drainpipes/downspouts from gutters to stop drains clogging, but allowing ash and water to empty from gutters onto the ground.
  • If you use a rainwater collection system for your water supply, disconnect the tank prior to ash falling.
    If you have chronic bronchitis, emphysema or asthma, stay inside and avoid unnecessary exposure to the ash.
  • Ensure livestock have clean food and water.
  • If you have children, know your school’s emergency plan and have indoor games and activities ready.
  • For more information on preparing for an ashfall:

A pause in the eruption, but ground cracks are widening and new steaming areas have appeared. At 8:08 a.m. HST on May 10, 2018 Geologist photographs a steaming crack about 50 meters (164 feet) west of Highway 130 in an area of earlier cracking. PC: US Geological Survey

East Rift Zone Eruption Update:

(Saturday, May 12, 2018 at 9:30 a.m.)


Hawaiian Volcano Observatory reports a new fissure in the lower East Rift Zone. Lava spatter was reported east of the geothermal plant property and northeast of Lanipuna Subdivision.

Continuing earthquakes, ground deformation, and sulphur dioxide emissions mean additional outbreaks of lava are possible.

HVO states that an explosive eruption at Halema’uma’u Crater is possible.  This could generate ash plumes and dangerous debris that may affect an area as far as 12 miles from the summit crater.

(Saturday, May 12, 2018 at 6 a.m.)

Hawaiian Volcano Observatory reports volcanic activity in the lower East Rift Zone of Kīlauea Volcano continues. None of the 15 fissure vents have produced any lava since Thursday. Continuing earthquakes, ground deformation, and sulphur dioxide emissions mean additional outbreaks of lava are possible.

HVO states that an explosive eruption at Halema’uma’u Crater is possible. This could generate ash plumes that may affect an area as far as 12 miles from the summit crater.

Maps and advisory information are available at links posted at the Civil Defense Eruption Updates website.

Due to the volcanic activity, the following are issued:

Residents of lower Puna between Kapoho and Kalapana, are advised to be on the alert in the event of possible gas emissions and volcanic eruption. There may be little to no advance notice to evacuate, so take this time to prepare.

If you evacuate voluntarily, the Pāhoa Community Center and Kea’au Community Center are open. Food will be provided and the shelters are pet-friendly.

Under Emergency Provisions, any looting or vandalism during an emergency is treated as a felony.

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