USGS Volcano Hazards Program Volcano Update
Recent Observations at Kilauea summit: The summit tiltmeter network recorded DI deflation at 7:30 am and DI inflation at about 5 pm yesterday. The lava lake level fell and rose mimicking tilt with the lava briefly overflowing onto the inner ledge at about 7 am this morning. The most recent (preliminary) sulfur dioxide emission rate measurement was 700 tonnes/day on February 1, 2013; this value is a typical background emission rate between rise/fall events. A very 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 and variable. Nine earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours: 1 within the upper east rift zone, 1 within the middle east rift zone, and 7 on south flank faults (including 2 located offshore). Over the past 6 months, the GPS receivers located on either side of the summit caldera have measured about 9 cm of extension - 2 cm/mo during the first 3 months and 1 cm/mo during the last 3 months with short-term minor fluctuations that mimicked tilt; a lack of data on the GPS satellite orbits has prevented calculation of GPS positions since January 29.
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 mostly below the inner ledge (~31 m or 100 ft below the floor of Halema`uma`u Crater on October 29, 2012) and has risen above and flooded the ledge in October, 2012, and January, 2013. 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: Lava activity on the coastal plain, fed by lava tubes extending from Pu`u `O`o, continued with no significant changes. An approximately 1 km-wide (0.6 mi wide) lava flow remained active on the coastal plain with very little surface activity straddling the easternmost boundary of Hawai`i Volcanoes National Park at the coast and entering the ocean at several locations, both inside and outside Hawai`i Volcanoes National Park. To the west, lava flows remained active with scattered breakouts and advanced very slowly from the base of the pali.
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.
At the Pu`u `O`o cone, a lava flow was spreading out on older Pu`u `O`o flows to the north of the cone while glow was visible from sources within Pu`u `O`o crater. Seismic tremor levels near Pu`u `O`o remained low. The most recent (preliminary) sulfur dioxide emission rate measurement was 200 tonnes/day on February 1, 2013, 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 - Most of the flow field is within the closed-access Kahauale'a Natural Area Reserve (NAR) and the abandoned Royal Gardens subdivision and can only be viewed from the air. A small part of the western flow field near the coast in within Hawai`i Volcanoes National Park (see below for access info). Under favorable weather conditions, active flows-when present-can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093). Pu`u `O`o Cone 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