Dust-blanketed crater rim severely overhung

Left. Several collapses of sections of the vent walls sent out thick clouds of rock dust (lithic ash) on Friday. This dust blanketed the crater rim at, and down-wind from, the closed tourist overlook above the vent, giving everything a sepia coloration. The ash-collection bucket in this photo is actually bright blue, as can be seen around the inner rim of the bucket. Right. Photos of the vent on Friday showed that the northern edge of the opening was severely overhung. A long slice of this overhang, noticeable on the right side of the vent in the photo, collapsed later that night, depositing even more ash on the crater rim.

KILAUEA VOLCANO (CAVW#1302-01-)
19.42°N 155.29°W, Summit Elevation 4091 ft (1247 m)
Volcano Alert Level: WATCH
Aviation Color Code: ORANGE

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. Hawai`i County Viewing Area status can be found at 961-8093.

Activity Summary for past 24 hours: A DI tilt event is nearing completion. Sulfur dioxide emission rates from Halema`uma`u have decreased but are still elevated. Emission rates from the Pu`u `O`o vents remain elevated. Tephra, predominantly rock dust, is still being produced by the Halema`uma`u vent At the east rift eruption site, lava flows through tubes to the ocean; surface flows are active on the coastal plain; the south TEB branch continues toward the ocean.

Past 24 hours at Kilauea summit: Yesterday, weak winds, rain, and fog produced wet and slightly voggy conditions at the summit. There was no glow recorded from the vent overnight. Clearer conditions his morning allow views of the plume which is rising at an angle tilted to the northeast.

Sulfur dioxide emission rates remain elevated and variable. The most recent average measurement was 300 tonnes/day on December 5, the lowest measurement since late December 2007 but still elevated above the 2003-2007 average rate of 140 tonnes/day. Measurements will resume when moderate trade winds return.

Tephra continues to be carried by the plume and deposited downwind of the vent. This morning's collection was mostly rock dust with some spatter bits, the largest measuring 6 mm (0.2 in) across. Some rockfalls but no gas-rushing (surf like) noises were heard during the collection.

The network of tiltmeters within the caldera recorded a DI tilt event with stuttered deflation starting 7:09 and resuming at around 10 am switching to inflation at 10:20 pm yesterday. The GPS receiver networks (less sensitive than tiltmeters) recorded no significant extension or contraction in the past week; over the past 3 months, the GPS network has recorded about 2 cm of contraction across the caldera.

Seismic activity continues to be focused on the south caldera; tremor levels, which have been at very low values since Dec. 4 increased during the DI tilt event; there were two short tremor bursts yesterday evening. A total of 23 earthquakes were strong enough to be located beneath Kilauea or nearby, with 16 beneath the summit caldera and 3 on south flank faults.

Past 24 hours at the middle east rift zone vents and flow field: Magma continues to degas through Pu`u `O`o Crater. The most recent sulfur dioxide emission rate measurement was 1,700 tonnes/day measured on December 5 similar to the 2003-2007 average of about 1,700 tonnes/day for this vent. No incandescence was observed within the crater overnight.

The tiltmeter on the north side of Pu`u `O`o recorded inflation-like signals which may be the result of almost 7 cm (2.8 in) of rain; the DI tilt event was strongly masked by the effects of rain. GPS stations spanning the crater (less sensitive than tiltmeters) recorded almost 4 cm of contraction over the past 3 months. Seismic tremor levels near Pu`u `O`o and the TEB vent remain at low values.

Lava from the TEB vent and the rootless shield complex continues to flow through tubes to the ocean; the south branch continues to creep through Hawai`i Volcanoes National Park. Yesterday, westerly winds closed the Public Viewing Area. Overnight, incandescence was seen from one location near the TEB vent in the area extending from the east rift eruption site to the top of the pali. GOES-WEST imagery of the island was totally blocked by dense clouds. This morning, CD officials report that a plume can be seen and that the winds were from the east.

HAZARD WARNING: The lava delta and adjacent areas both inland and out to sea are still some of the most hazardous areas on the flow field. Frequent delta/bench collapses give little warning, can produce hot rock falls inland and in the adjacent ocean and can produce large but 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 has been responsible for many injuries and a few deaths.

Definitions of terms used in the update:

glow: light from source that is not seen, indirect light.

FLIR: Forward Looking InfraRed, a camera which directly images heat rather than visible light. If volcanic fume is not too rich in water vapor, a FLIR can see through it to image hot surfaces.

pali: Hawaiian word for cliff or steep incline. In the context of the TEB flow field, 'pali' usually refers to Pulama pali that bisects the abandoned Royal Gardens subdivision.

CD: Hawai`i County Civil Defense

DOH air quality monitoring: see Hawai`i State Department of Health Air Quality website http://hawaii.gov/doh/air-quality/index.html .

bomb: lava fragment ejected into the air while molten acquiring aerodynamic shapes in flight; the term is restricted to pieces larger than 6.4 cm (2.5 in.). See http://volcanoes.usgs.gov/Products/Pglossary/bomb.html

hybrid, or explosion, seismic signals: complex earthquakes that are a hybrid of different signals. They start as a high frequency earthquake, similar to typical rock-breaking or rock fall events, that transitions to very long, 20-30 second, period (VLP) oscillations that continue for several minutes. At HVO, we observed these signals with the four small Halema`uma`u explosive eruptions in March, April, and August 2008. Several more similar signals, some as strong as the explosion signals associated with the four explosive eruptions, have been recorded without obvious evidenceof surface eruption such as rock fragments or other debris.

MODIS satellite: a NASA satellite pair, Aqua and Terra, which passes over Hawai`i twice a day. During daylight hours, the images are taken at about 11 am and 2 pm H.s.t. This imagery can be viewed about 3-5 hours after acquisition at http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=AERONET_Mauna_Loa.

GOES-WEST satellite: a geostationary NOAA satellite used most often for weather tracking. Images are typically acquired every 15 minutes. The loop http://www.ssd.noaa.gov/VAAC/kilauea/sloop-vis.html is posted by the Washington DC Volcanic Ash Advisory Center for the purpose of tracking emissions from Hawai`i volcanoes. The imagery automatically switches from infrared at night to visual during the day. Recently, it has been useful for tracking volcanic gas emissions from Halema`uma`u, Pu`u `O`o, and the Waikupanaha ocean entry during the day and hot lava flows at night.

Volcano Watch: weekly newspaper-like article written by HVO scientists on a volcano topic of interest. These articles are usually printed in the Sunday editions of the Hawai`i Island newspapers Hawaii Tribune Herald and West Hawaii Today. More than 800 of these articles have been written and are archived on the HVO website (menu at the bottom of the homepage hvo.wr.usgs.gov).

VLP seismic tremor: seismic tremor is continuous ground vibrations simultaneously at many different frequencies. VLP is a very long period or very low frequency component which, at the Halema`uma`u vent, has a period of 20-30 seconds or a frequency of 0.03-0.05 cycles per second (Hertz or Hz).

RB2S2BL earthquakes: earthquakes that were recorded but were too small to be located. These quakes have magnitudes less than 1.7 and may only be recorded by one or two seismometers. Recording at a minimum of 4 seismometer sites is required to locate an earthquake.

wink: an abrupt shutting off of incandescence at a vent lasting for several minutes. At the Halema`uma`u vent, winks usually start with or immediately follow a small, local earthquake. The diminishment of incandescence is due to the plume changing from translucent to opaque with rock dust.

tonne: metric unit equal to 1,000 kilograms, 2,204.6 lbs, or 1.1 English tons.

microradian: a measure of angle equivalent to 0.000057 degrees.

ppm: parts-per-million; 10,000 ppm = 1 %.

littoral cone: usually small cones built near active ocean entries; the cones are constructed of tephra from steam explosions that are sometimes produced when 1,150 degree C lava enters the 25 degree C ocean.

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 the temperature of the surface. 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).

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.

TEB: Thanksgiving Eve Breakout, the designation used for lava flows that started with a breakout on November 21, 2007.

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 eruption site, as many of the DI events at Kilauea summit are also recorded at a tiltmeter at Pu`u `O`o, delayed by 1-2 hours. DI events often correlate with lava pulses and/or pauses in the eruption at the Pu`u `O`o/July 21/TEB vents.


Maps, photos, webcam views, and other information about Kilauea Volcano are available at http://volcano.wr.usgs.gov/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/2006/warnschemes.html