Volcano Update from Archive
This report on the status of Kilauea volcanic activity, in addition to maps, photos, and Webcam images (available using the menu bar above), was prepared by the USGS Hawaiian Volcano Observatory (HVO). Hawai`i Volcanoes National Park status can be found at http://www.nps.gov/havo/ or 985-6000. All times are Hawai`i Standard Time.
KILAUEA VOLCANO (CAVW #1302-01-)
19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
Activity Summary for past 24 hours: The summit contraction slowed and weak extension may be returning; back-to-back DI tilt events were shorter but continued during which lava lake levels rose and fell with tilt. At Pu`u `O`o, glow persisted from the usual sources and, to the southeast, surface flows from new breakouts were active but had not reached the ocean. Seismic tremor levels were generally low; gas emissions were elevated.
Past 24 hours at Kilauea summit: The summit tiltmeter network recorded DI deflation at 9 am quickly followed by DI inflation at 6 pm yesterday. The lava lake level changes were obscured by a rise/fall event between 11:30 am and 5 pm yesterday but the lake level did rise with DI inflation afterward. The most recent (preliminary) sulfur dioxide emission rate measurement was 300 tonnes/day on May 11, 2012. Although not measured over the weekend, small amounts of ash-sized tephra, including fresh bits of spatter from spattering at the edge of the lava lake, were likely wafted out of the vent within the gas plume and deposited on nearby surfaces.
Since April 27 2012, the GPS network recorded weak contraction that may be returning to weak extension. Seismic tremor levels were low but increased temporarily with the brief appearance of vigorous spattering sinks on the west edge of the lake just before and after the above-mentioned lava lake rise/fall event. Eleven earthquakes were strong enough to be located beneath Kilauea volcano: 1 beneath the lower southwest rift zone, 1 just south of the summit caldera, and 9 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.
Past 24 hours at the middle east rift zone vents: Lava flow activity continued on the pali and the coastal plain southeast of Pu`u `O`o. Mapping by HVO geologists over the past two days showed that the active flows have re-entered Hawai`i Volcanoes National Park. Webcam images showed that the newest flows did not advance much overnight across the coastal plain and were still more than 1 km (0.6 mi) from the ocean. Consequently, there was no ocean entry.
The tiltmeter on the north flank of Pu`u `O`o cone recorded weak inflation and showed no obvious response to the summit tilt changes. Strong glow persisted from the lava pond in the enlarged pit crater on the east edge of the crater floor, a small spatter cone on the southeast edge of the floor, and 2 skylights on the uppermost part of the tube system. Seismic tremor levels near Pu`u `O`o were low. GPS receivers on opposite sides of the cone recorded contraction since April 27 but may be returning to weak extension. The most recent (preliminary) sulfur dioxide emission rate measurement was 400 tonnes/day on May 8, 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 has continued since at Pu`u `O`o Cone, or from vents within a few kilometers to the east or west, with few interruptions. 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. The ocean entry has been inactive since late December but the flows have remained intermittently active on the pali and the coastal plain. 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 - Active lava flows within the closed-access Kahauale'a Natural Area Reserve (NAR) and the evacuated Royal Gardens subdivision can only be viewed from the air. Under favorable weather conditions, the flows can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093) and in the R2, R3, and R4 webcams. Pu`u `O`o Cone and Kilauea Crater - these areas are within Hawai`i Volcanoes National Park; access and viewing information can be found at http://www.nps.gov/havo/planyourvisit/lava2.htm.
Maps, photos, Webcam views, and other information about Kilauea Volcano are available at http://volcanoes.usgs.gov/hvo/activity/kilaueastatus.php. A daily update summary is available by phone at (808) 967-8862.
A map with details of earthquakes located within the past two weeks can be found at http://hvo.wr.usgs.gov/seismic/volcweb/earthquakes/
A definition of alert levels can be found at http://volcanoes.usgs.gov/activity/alertsystem/index.php
Definitions of Terms Used:
DI tilt event: DI is an abbreviation for 'deflation-inflation' and describes a geophysical event of uncertain volcanic significance. DI events are recorded by tiltmeters at Kilauea summit as an abrupt deflation of up to a few microradians in magnitude lasting several hours (weak DI events) to 2-3 days (strong DI events) followed by an abrupt inflation of approximately equal magnitude. The tilt events are usually accompanied by an increase in summit tremor during the deflation phase. A careful analysis of these events suggests that they may be related to changes in magma supply to a storage reservoir at less than 1 km depth, just east of Halema`uma`u crater. Usually, though not always, these changes propagate through the magma conduit from the summit to the east rift eruption site, as many of the DI events at Kilauea summit are also recorded at a tiltmeter at Pu`u `O`o delayed by several hours. DI events often correlate with lava pulses and/or pauses in the eruption at the Pu`u `O`o/Peace Day vents.
fill-and-drain, rise/fall cycles or high lava stands: one of the cyclical behaviors exhibited by the summit lava lake. A cycle starts with a rise in lava level, a decrease in summit tremor amplitude, and a small decrease in tilt. After a period of minutes to hours, the lava will abruptly drain back to its previous level, seismic tremor amplitude will increase for a short time (a seismic tremor burst), and summit tilt will return to its previous level. Although not measured continuously, spot checks of gas emissions demonstrate that far less gas is released during the high lava stand than during its draining phase suggesting that, during the high lava stand, lava is puffed up with gas trapped by crusts on the lava surface; the gas plume will also get thin and wispy during these cycles returning to more robustness afterward.
perched lava lake: a lava lake within a rim that is progressively built up by overflows of lava that have cooled and solidified. The most recent example of a perched lava lake is currently active within Pu`u `O`o maintaining a rim standing several meters (yards) above the crater floor. In many ways, a perched lava lake resembles an above-ground swimming pool. Overflows from the pond add layers to the surrounding crater floor building it higher; the overflows also build up the perched lake rim, continually keeping the lake rim raised above the floor.
mauka, makai: Hawaiian terms for directions relative to the coast - makai or ma kai (toward the coast) and mauka or ma uka (toward the highlands or away from the coast).
composite seismic events: is a seismic signal with multiple distinct phases that has been recorded frequently at HVO from the Halema`uma`u Overlook vent area since its explosive opening in March, 2008. For the composite events recorded at Halema`uma`u, we typically see an initial high frequency vibration lasting for a few seconds that have been correlated with rockfalls. This is followed by about 30 seconds of a long-period (LP) oscillation with an approximately 2- to 3-second period. The final phase of the signal is several minutes of a very-long-period (VLP) oscillation with an approximately 25- to 30-second period. The LP signals are interpreted to be from the uppermost portion of the conduit and VLP signals are interpreted to be fluid passing through a deep constriction in the conduit through which lava rises to the pond surface we see in the webcam.
Halema`uma`u Overlook vent: has been difficult to describe concisely. The vent is actually a pit, or crater, in the floor of the larger Halema`uma`u Crater in the floor of the larger Kilauea caldera or crater - a crater within a crater within a crater. It is easiest to describe as a pit inset within the floor of a crater within a caldera. The pit is about 140 m (460 ft) in diameter at the Halema`uma`u Crater floor, is about 50 m in diameter at the pit floor, and is about 200 m (660 ft) deep. As of November, 2009, a lava pond surface has been visible in a hole in the floor of this pit.
glow: light from an unseen source; indirect light.
incandescence: the production of visible light from a hot surface. The term also refers to the light emitted from a hot surface. The color of the light is related to surface temperature. Some surfaces can display dull red incandescence at temperatures as low as 430 degrees Centigrade (806 degrees Fahrenheit). By contrast, molten lava displays bright orange to orange-yellow light from surfaces that are hotter than 900 degrees C (1,650 degrees F).
CD: Hawai`i County Civil Defense
tonne: metric unit equal to 1,000 kilograms, 2,204.6 lbs, or 1.1 English tons.
tephra: all material deposited by fallout from an eruption-related plume, regardless of size.
ash: tephra less than 2 mm (5/64 inches) in size.
microradian: a measure of angle equivalent to 0.000057 degrees.
More definitions with photos can be found at http://volcanoes.usgs.gov/images/pglossary/index.php.
The Hawaiian Volcano Observatory is one of five volcano observatories within the U.S. Geological Survey and is responsible for monitoring volcanoes and earthquakes in Hawai`i.
