USGS Volcano Hazards Program Volcano Update
Recent Observations at Kilauea summit: The summit tiltmeters recorded continued DI inflation into a seventh day this morning and the lava lake level appeared to stabilize at a level just below the built-up inner ledge with rise/fall events that episodically submerge the inner ledge; the highest lava rise of the rise/fall events has not yet submerged the top of the spatter rampart on the inner ledge which is 46 m (150 ft) below the Halema`uma`u Crater floor; in addition to the rise/fall events and variations in circulation patterns, there was also a rockfall into the lake at 1:30 pm yesterday. The most recent (preliminary) sulfur dioxide emission rate measurement was 1,200 tonnes/day on September 28, 2012; this value is rather high but not out of the range of values measured at the summit over the past several months; new measurements must await the return of moderate trade winds. Although not measured today, small amounts of ash-sized tephra (fresh spatter bits and Pele's hair) were almost certainly carried out of the vent in the gas plume and deposited on nearby surfaces.
Seismic tremor levels fluctuated through the rise/fall events mentioned above - dropping to near-zero values while the lava lake level rose and spiking as the lava dropped to its previous level. The GPS receiver network recorded weak extension across the caldera since early August. Nineteen earthquakes were strong enough to be located beneath Kilauea: 1 west of the summit, 7 beneath the summit caldera, 4 within the upper east rift zone (between Pauahi Crater and the main Mauna Ulu vent), and 7 on south flank faults.
Background: The summit lava lake is deep within a ~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 fluctuates from about 60 m to more than 150 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. Most recently, the lava level of the lake has remained below an inner ledge (60 m or 200 ft below the floor of Halema`uma`u Crater on May 9, 2012) and responded to summit tilt changes with the lake receding during deflation and rising during inflation.
Recent Observations at the middle east rift zone vents: Lava continued to pool at the base of the pali within the abandoned Royal Gardens subdivision without significant seaward progress across the coastal plain. The pali flows have been visible from the County Viewing Area located to the east in Kalapana and mobile cam 3 while the flows on the coastal plain are in view of mobile cams 2 and 4.
The tiltmeter on the north flank of Pu`u `O`o cone continued to record fluctuations on a weak inflationary trend; any Pu`u `O`o tilt response to summit DI events has been significantly decreased since the end of January, 2012. Seismic tremor levels near Pu`u `O`o were low. The most recent (preliminary) sulfur dioxide emission rate measurement was 220 tonnes/day on September 28, 2012, from all east rift zone sources.
At Pu`u `O`o Crater, the east pit lava lake remained at a stable level and continued to circulate; lava episodically flowed across the south pit floor; glow was again seen from points on the west edge of the crusted north pit; the spot at the base of the southeast flank of Pu`u `O`o, marking a collapse in the roof of the tube feeding lava flows downslope, glowed weakly overnight in the Pu`u `O`o east cam.
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. Since late December, the flows have remained intermittently active on the pali and the coastal plain but have not entered the ocean. 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 within the Royal Gardens subdivision; the lava flows do not pose a hazard to any structures not already within the County-declared mandatory evacuation zone. 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 new breakout 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, glow from these flows may be reflected in clouds which 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