USGS Volcano Hazards Program Volcano Update

HVO update page and observatory web site

Activity Summary: Vigorous lava flow activity continued from the north spatter cone within Pu`u `O`o crater and filled the northern part of the crater floor repeatedly. The Kahauale'a flow is dead except for a small breakout at the base of the Pu`u `O`o cone. The Peace Day flow continued to enter the ocean more than 10 km to the southeast. At the summit, DI deflation and a dropping, circulating lava lake started yesterday morning and continued overnight. Gas emissions remained elevated.

Recent Observations at Kilauea summit: The summit tiltmeter network recorded the start of weak DI deflation at 8:40 am with stronger deflation beginning at 6 pm yesterday. The lava lake level dropped slowly after 9 am yesterday but its rate of descent increased dramatically after 6 pm. The most recent (preliminary) sulfur dioxide emission rate measurement was 700 tonnes/day on April 18, 2013; these measurements were made as spattering was starting up. The gas plume still contains a very small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair) out of the vent and deposits it on nearby surfaces.

Seismic tremor levels remained low and steady with the expected swings in value - strong tremor accompanied spattering along the lava lake edges. Seven earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours: 1 beneath the lower southwest rift zone, 2 south of Halema`uma`u Crater, 1 in the middle east rift zone near Pu`u `O`o, and 3 on south flank faults. Since mid-March, the GPS receivers located on either side of the summit caldera recorded short periods of extension and contraction across the summit area mimicking DI tilt events superposed over slow contraction (slightly more than a centimeter) with no significant extension or contraction since early April; for comparison, these same GPS receivers recorded over 30 cm of extension between early 2010 and mid-February 2013.

Background: The summit lava lake is 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 before receding to greater depths. 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: Further review of Webcam data showed that the lava flow from the north spatter cone within Pu`u `O`o crater started just before midnight on April 19 and became more vigorous around 1 am on April 20 when deflation of the Pu`u `O`o cone started; there were three more lava pulses from the north spatter cone at about 8 am, 3:15 pm, and 11:50 pm yesterday. The lava flows brought active lava about 10 m (about 30 ft) below the north rim of Pu`u `O`o Crater where the HVO Webcams were located and the heat caused the POcam tripod to warp tilting the camera downward; HVO geologists inspected the scene mid-morning yesterday and moved the equipment farther back from the crater rim.

The two spatter cones on the south portion of the crater also issued lava flows briefly around noon when the HVO crew was departing Pu`u `O`o. The small lava pond on the northeast crater edge overflowed a small amount at about 11:30 pm last night, just before the fourth lava pulse from the north spatter cone. The tiltmeter on the north flank of Pu`u `O`o cone recorded almost 1 microradian of deflation before stabilizing around 11 am and finally recording inflation after 5 pm yesterday. Seismic tremor levels near Pu`u `O`o remained low with added bursts of tremor between 7:40 am and 4 pm yesterday. The most recent (preliminary) sulfur dioxide emission rate measurement was 250 tonnes/day on April 17, 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.

The Kahauale`a flow was not active when inspected from the air yesterday; however, the increased lava activity within Pu`u `O`o apparently injected lava into the Kahauale`a tube resulting in a small outbreak at the northeast base of Pu`u `O`o at about 6:30 am yesterday that remained sporadically active through this morning.

The Peace Day lava flow continued to be active on the pali and the coastal plain with no significant changes - a patch of active breakouts on the pali southeast from Pu`u `O`o (visible in occasional satellite images but not in our Webcams and reported from the Kalapana Viewing Area), and several branches on the coastal plain. The main branch of the Peace Day flow continued to enter the ocean at 2-3 persistent locations (inside and outside Hawai`i Volcanoes National Park) with the eastern plume being the strongest. Multiple narrow flow branches to the west were active as scattered breakouts on the pali, near the base of the pali and extending nearly to the coast.

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.

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

Update in Common Alerting Protocol (CAP) format