Hawaii Volcano National Park - Current Update

HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE

Friday, February 3, 2012 7:02 AM HST (Friday, February 3, 2012 17:02 UTC)

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: Overall eruptive activity was low. DI deflation slowed and the lava lake was perturbed by two large collapses of the vent rim. Within Pu`u `O`o Crater, glow was visible from several sources on the northeast and southeast edges of the floor. Surface flows southeast of Pu`u `O`o remained active but possibly weaker according to satellite imagery. Overall seismic tremor levels were low and gas emissions were elevated.

Past 24 hours at Kilauea summit: The summit tilt network continued to record DI deflation punctuated with two abrupt positive offsets due to large rockfalls from the vent rim (Halema`uma`u Crater floor) into the lake at 9:30 pm and midnight; the first collapse involved a portion of the north rim while the second took a long sliver of the northeast rim; the first collapse apparently induced secondary collapses of the inner ledge and ejected hot spatter onto the nearby portions of the Halema`uma`u Crater floor; the second collapse deposited a large amount of debris into the northeast side of the lava lake. Both collapses severely disrupted the lava lake with the second significantly dropping the level which was slowly recovering lost elevation this morning. The most recent (preliminary) sulfur dioxide emission rate measurement was 600 tonnes/day on January 30, 2012.

Seismic tremor levels dropped when a small spattering source appeared on the north rim of the lake at 8:20 pm last night and remained low with the two large rockfall seismic signals superimposed. Ten earthquakes were strong enough to be located beneath Kilauea volcano: one north of and one beneath the summit caldera, one within the upper east rift zone, and seven on south flank faults.

Background: The summit lava lake is deep within a ~150 m (500 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 70 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 (75 m or 250 ft below the floor of Halema`uma`u Crater) 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: The tiltmeter on the north flank of Pu`u `O`o cone continued to record DI deflation until about 5 pm yesterday when the deflation stopped and tilt became variable. At Pu`u `O`o, glow was visible from sources on the northeast and southeast edges of the crater floor. Seismic tremor levels near Pu`u `O`o remained low. The most recent (preliminary) sulfur dioxide emission rate measurement was 500 tonnes/day on January 29, 2012, from all east rift zone sources.

Thermal anomalies in both MODIS and GOES satellite imagery of the flow field appeared slightly weaker suggesting that the surface flow activity 4 km (2.5 mi) southeast of Pu`u `O`o remained active but weaker and may be stalling. Farther southeast, Webcams recorded above or on the pali and coastal plain nor any active ocean entries.

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. In early August, 2011, the Pu`u `O`o crater floor collapsed to a depth of about 75 m (245 ft) below the east rim of the crater as lava burst from vents on the lower west flank of the cone. A DI tilt event several days later cut off supply to Pu`u `O`o and the west flank vents; lava reappeared in Pu`u `O`o Crater on August 21st and filled it to overflowing. 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 entry has been inactive since late December and the flows have been weakly active since mid-January. 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 and adjacent State land managed by the Department of Land and Natural Resources; they 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 - There are minor active lava flows within the closed-access Kahauale'a Natural Area Reserve (NAR) but not on private property within the abandoned Royal Gardens subdivision. The NAR can only be viewed from the air and, indirectly, from the County Viewing Area at Kalapana. Pu`u `O`o Cone, the (inactive) West Ka`ili`ili lava ocean entry, 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://tux.wr.usgs.gov/

A definition of alert levels can be found at http://volcanoes.usgs.gov/activity/alertsystem/index.php

Definitions of Terms Used:

fill-and-drain cycles: one of the cyclical behaviors exhibited by the summit lava lake. A fill-and-drain 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, 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.

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.

DI tilt event: DI is an abbreviation for 'deflation-inflation' and describes a volcanic event of uncertain 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 to 2-3 days 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/July 21/TEB vents.

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. Source: Kilauea Volcano Observatory



Information courtesy of ...
U.S. Geological Survey Hawaiian Volcano Observatory (HVO).
USGS Cascades Volcano Observatory
Cascade Range Current Update
USGS Alert-Notification System for Volcanic Activity
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