USGS Volcano Hazards Program Volcano Update
Recent Observations at Kilauea summit: The summit tiltmeter network recorded the switch to DI inflation at about 4 am this morning but the lava lake had not yet started to rise by the time of this posting; while at a relatively low level during DI deflation, there were several instances of lava veneer peeling off the walls and falling into the lake temporarily creating vigorous spattering and lake disturbance. The most recent (preliminary) sulfur dioxide emission rate measurement was 700 tonnes/day on March 5, 2013; this value is within the range of higher emission rates during periods when lava sinks are spattering on the lake surface; new measurements must await the return of moderate trade winds. A very small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair) was carried out of the vent in the gas plume and deposited on nearby surfaces.
Seismic tremor levels were low - tremor values and SO2 concentrations near the vent sporadically dropped to near-zero values when spattering was largely absent three times overnight. Four earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours: 1 within the middle east rift zone, and 3 on south flank faults. Since mid-February, the GPS receivers located on either side of the summit caldera have recorded short periods of extension and contraction across the summit area, mimicking the summit DI tilt events, but no significant longer-term trend.
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: Within the Pu`u `O`o crater, the usual four spatter cones on the crater floor continued to glow overnight. The tiltmeter on the north flank of Pu`u `O`o cone recorded minor fluctuations with a few sharp increased that correlate perfectly with the onset of rain showers in the area. Seismic tremor levels near Pu`u `O`o remained low. The most recent (preliminary) sulfur dioxide emission rate measurement was 400 tonnes/day on March 4, 2013, from all east rift zone sources; these values have typically been between 200 and 300 t/d from November through January and 200-400 t/d through February. Two lava flows (Peace Day and Kahauale`a) were fed by lava tubes extending from Pu`u `O`o:
Peace Day lava flow activity on the pali and the coastal plain continued in several areas with no significant changes - a patch of active breakouts just above the pali about 5 km (3 mi) southeast from Pu`u `O`o (visible in occasional satellite images and from the Kalapana Viewing Area but not in our Webcams), and several branches on the coastal plain. The main branch of the Peace Day flow continued to enter the ocean at two main locations (inside and outside Hawai`i Volcanoes National Park). A flow branch to the west was active as scattered breakouts between the base of the pali and the mid-coastal plain (visible in mobile cam 2).
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 Kahauale`a flow remained weakly active along the north base of the 2007 perched channel over older flows from the 30-year ongoing eruption and continued activity to the northeast from Pu`u `O`o more than 4.4 km (2.7 mi) across the Kahauale`a NAR and into Wao Kele o Puna land. A branch to south was infrequently active in the vicinity of Pu`u Kahaualea.
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 (Peace Day 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. The Kahauale`a flow started from the spatter cone/lava lake at the northeast edge of the Pu`u `o`o crater floor in mid-January, 2013, and advanced north to the base of the cone before turning to the northeast and splitting at the base of the 2007 perched channel. 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