HVO/USGS Volcanic Activity Notice Kīlauea Volcano 8:02 a.m. HST

Release Date:

The steady lowering of the lava lake in "Overlook crater" within HALEMAUMAU at the summit of KILAUEA Volcano has raised the potential for explosive eruptions in the coming weeks.

   Volcano: KILAUEA (VNUM #332010)
   Current Volcano Alert Level: WARNING
   Current Aviation Color Code: ORANGE
   Issued: Wednesday, May 9, 2018, 8:02 AM HST
   Source: Hawaiian Volcano Observatory
   Location: N 19 deg 25 min W 155 deg 17 min
   Elevation: 4091 ft (1247 m)
   Area: HAWAII

Volcanic Activity Summary: The steady lowering of the lava lake in "Overlook crater" within Halema‘uma‘u at the summit of Kīlauea Volcano has raised the potential for explosive eruptions in the coming weeks. If the lava column drops to the level of groundwater beneath Kīlauea Caldera, influx of water into the conduit could cause steam-driven explosions. Debris expelled during such explosions could impact the area surrounding Halema‘uma‘u and the Kīlauea summit. At this time, we cannot say with certainty that explosive activity will occur, how large the explosions could be, or how long such explosive activity could continue.

Residents of the Kīlauea summit area should learn about the hazards of ashfall, stay informed of the status of the volcano and area closures, and review family and business emergency plans.

Resource on volcanic ash hazards: https://volcanoes.usgs.gov/volcanic_ash/

Primary hazards of concern should this activity occur are ballistic projectiles and ashfall.

During steam-driven explosions, ballistic blocks up to 2 m (yards) across could be thrown in all directions to a distance of 1 km (0.6 miles) or more. These blocks could weigh a few kilograms (pounds) to several tons.

Smaller (pebble-size) rocks could be sent several kilometers (miles) from Halema‘uma‘u, mostly in a downwind direction.

Presently, during the drawdown of the lava column, rockfalls from the steep enclosing walls of the Overlook crater vent impact the lake and produce small ash clouds. These clouds are very dilute and result in dustings of ash (particles smaller than 2 mm) downwind.

Should steam-driven explosions begin, ash clouds will rise to greater elevations above ground. Minor ashfall could occur over much wider areas, even up to several tens of miles from Halema‘uma‘u. In 1924, ash may have reached as high as 20,000 feet above sea level. Small amounts of fine ash from these explosions fell over a wide area as far north as North Hilo (Hakalau), in lower Puna, and as far south as Waiohinu.


Gas emitted during steam-drive explosions will be mainly steam, but will include some sulfur dioxide (SO2) as well. Currently, SO2 emissions remain elevated.

Steam-driven explosions at volcanoes typically provide very little warning. Once the lava level reaches the groundwater elevation, onset of continuous ashy plumes or a sequence of violent steam-driven explosions may be the first sign that activity of concern has commenced.