USGS Volcano Hazards Program Volcano Update
Recent Observations at Kilauea summit: The summit tiltmeter network recorded an entire weak DI event starting at about 8 am yesterday, switching to weak inflation at about 10 pm last night and starting another weak deflation at about 6 am this morning. The lava lake surface fell, rose, and fell small amounts, mimicking the tilt. The most recent (preliminary) sulfur dioxide emission rate measurement was 900 tonnes/day on December 27, 2012. A small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair) was likely carried out of the vent in the gas plume and deposited on nearby surfaces.
Seismic tremor levels were low. Four earthquakes were strong enough to be located beneath Kilauea over the past 24 hours: 1 to the west and 1 to the south of the summit caldera, 1 within the upper east rift zone, and 1 on south flank faults.
Background: The summit lava lake is deep within an ~160 m (520 ft) diameter cylindrical vent with nearly vertical sides inset within the east wall and floor of Halema`uma`u Crater. Its level has varied from about 25 m to more than 200 m (out of sight) below the floor of Halema`uma`u Crater. The vent has been mostly active since opening with a small explosive event on March 19, 2008. The surface level of the lava lake has remained below the inner ledge (~31 m or 100 ft below the floor of Halema`uma`u Crater on October 29, 2012) and has not risen above and flooded the ledge since October 28, 2012. The lake level responds to summit tilt changes with the lake receding during deflation and rising during inflation.
Recent Observations at the middle east rift zone vents: There were no significant changes on the coastal plain. Lava is active on the pali and an approximately 1 km-wide (0.6 mi wide) lava flow remained active on the coastal plain with scattered surface activity extending from mid-coastal plain to the coast and straddling the easternmost boundary of Hawai`i Volcanoes National Park. Webcams recorded more persistent but still weak ocean entry plumes yesterday; lava is reported sporadically entering the ocean at multiple locations.
HAZARD ALERT: Lava entering the ocean builds lava deltas. The lava delta and adjacent areas are some of the most hazardous areas on the flow field. Frequent delta/bench collapses give little warning, can produce explosions capable of throwing both dense and molten rocks hundreds of meters (yards) in all directions (inland as well as out to sea), and can produce damaging local waves. The steam plume produced by lava entering the ocean contains fine lava fragments and an assortment of acid droplets that can be harmful to your health. The rapidly changing conditions near the ocean entry have been responsible for many injuries and a few deaths.
The tiltmeter on the north flank of Pu`u `O`o cone recorded weak inflation that was enhanced by rainfall after 9 pm last night. Within Pu`u `O`o crater, lava issued from the easternmost spatter cone in the south part of the crater floor between 8 and 10 am yesterday and 5:30 to about 7:30 am this morning. Seismic tremor levels near Pu`u `O`o remained low. The most recent (preliminary) sulfur dioxide emission rate measurement was 200 tonnes/day on December 26, 2012, from all east rift zone sources.
Background: The eruption in Kilauea's middle east rift zone started with a fissure eruption on January 3, 1983, and continued with few interruptions at Pu`u `O`o Cone, or temporarily from vents within a few kilometers to the east or west. A fissure eruption on the upper east flank of Pu`u `O`o Cone on Sept. 21, 2011, drained the lava lakes and fed a lava flow that advanced southeast through the abandoned Royal Gardens subdivision to the ocean within Hawai`i Volcanoes National Park in early December 2011. Since late December 2011, the flows have remained intermittently active on the pali and the coastal plain and finally re-entered the ocean starting on November 24, 2012. In general, activity waxes with inflation and wanes with deflation.
Hazard Summary: East rift vents and flow field - near-vent areas could erupt or collapse without warning with spatter and/or ash being wafted within the gas plume; potentially-lethal concentrations of sulfur dioxide gas may be present within 1 km downwind of vent areas. All recently active lava flows are within Hawai`i Volcanoes National Park, adjacent State land managed by the Department of Land and Natural Resources, and private property; the lava flows do not pose a hazard to any structures not already within the County-declared mandatory evacuation zone. Lava deltas, which can collapse into the ocean without warning, are extremely hazardous and should be avoided (see HAZARD ALERT above). Kilauea Crater - ash and Pele's hair can be carried several kilometers downwind; potentially-lethal concentrations of sulfur dioxide can be present within 1 km downwind.
Viewing Summary: East rift zone flow field - The active lava flows were within the closed-access Kahauale'a Natural Area Reserve (NAR) and the abandoned Royal Gardens subdivision and can only be viewed from the air. Under favorable weather conditions, these flows can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093). Pu`u `O`o Cone, the strip of coastal plain nearest the ocean, and Kilauea Crater - these areas are within Hawai`i Volcanoes National Park; Park access and viewing information can be found at http://www.nps.gov/havo/planyourvisit/lava2.htm.
Update in Common Alerting Protocol (CAP) format