Volcano Update from Archive



HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
Tuesday, September 24, 2013 7:24 AM HST (Tuesday, September 24, 2013 17:24 UTC)


This report on the status of Kilauea volcanic activity, in addition to maps, photos, and Webcam images (available at http://hvo.wr.usgs.gov/activity/kilaueastatus.php), 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: Eruption at two locations continued with no significant changes. Summit instruments recorded weak inflationary tilt while the lava lake level fluctuated but remained fairly stable. At the middle east rift zone, the Kahauale`a 2 lava flow was active as multiple breakouts burning two patches of forest north of Pu`u `O`o. The Peace Day flow southeast of Pu`u `O`o may host two small breakouts in its upper flow field. Gas emissions remained elevated.

Recent Observations at Kilauea summit: Summit tiltmeters weak inflationary tilt (about +0.3 microradians/day). The lava lake level dropped a few meters early yesterday and recovered during yesterday to about 54-55 m (177-180 ft) below the Halema`uma`u Crater floor this morning. Gas emissions continued to be elevated: the most recent sulfur dioxide emission rate measurement was 1,100 t/d on September 23, 2013 - the higher value represents a period in which spattering activity and gas release from the lava lake were active; however, all of these values are minimums because the data were acquired close to the vent where the plume is most dense and challenging to fully characterize. A small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair from the spattering sinks) was carried out of the vent with the gas and deposited onto nearby surfaces.

Seismic tremor levels remained low with no dropouts. Six earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours all on south flank faults. GPS data reductions have been unavailable since Sept. 17; we are working on the problem and hope to have it resolved soon.

Background: The summit lava lake is within a cylindrical vent cavity with a diameter of ~160 m (520 ft) and 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 generally receding during deflation and rising during inflation.

Recent Observations at the middle east rift zone vents: The tiltmeter at Pu`u `O`o cone recorded a -0.5 microradian drop and recovery between 10:30 am and 10 pm yesterday that was not correlated with any visible change in behavior. The most recent (preliminary) sulfur dioxide emission rate measurement was 300 tonnes/day on September 23, 2013, from all east rift zone sources; these values have ranged between 150 and 450 t/d in 2013 and are made at a greater distance from the sources where the plume is more easily characterized. GPS data reductions have not been available since Sept. 17; we are working to resolve the problem. The Pu`u `O`o vent fed two lava flow fields - most of the lava appeared to be feeding the Kahauale`a 2 flow to the north while activity on the older Peace Day flow to the southeast was only present in two small patches above the pali.

Spatter cones on the north and south portion of the Pu`u `O`o crater floor showed continued incandescence while the northeast spatter cone continued to feed the Kahauale`a 2 lava flow extending 3.6 km (2.2 mi) to the north (as of 9/19). PNcam views showed scattered active breakouts on the Kahauale`a 2 flow and burning along the forest line north of Pu`u `O`o.

HVO geologists on an overflight Thursday (9/19) found two small breakouts on the Peace Day flow 2.7 km (1.7 mi) and 6 km (3.7 mi) southeast of Pu`u `O`o above the pali; a MODIS image overnight included only weak thermal anomalies in this area suggesting that this minor activity may be waning. There were no signs of lava activity farther southeast (no lava activity on the pali or the coastal plain and no lava entering the ocean).

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, which started from the spatter cone/lava lake at the northeast edge of the Pu`u `O`o crater floor in mid-January, 2013, was dead by late April, but a new flow (Kahauale`a 2) became active in the same general area in early May. 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. 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. Under favorable weather conditions, active flows-when present-can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093) and from the end of the Chain of Craters Road within Hawai`i Volcanoes National Park. 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.

Additional Information:

For a definition of volcano alert levels and aviation color codes: http://volcanoes.usgs.gov/activity/alertsystem/index.php

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/

HVO Contact Information:

askHVO@usgs.gov

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.

rise/fall events: one of the episodic behaviors exhibited by the summit lava lake starting in 2009. An event starts with a rise in lava level, a decrease in high-frequency summit tremor amplitude, a decrease or total stoppage of spattering, and a small decrease in tilt. After a period of minutes to hours, the lava will abruptly drain back to its previous level amidst resumed vigorous spattering, seismic tremor amplitude will increase for a short time (a seismic tremor burst) before resuming background levels, and summit tilt will return to its previous level. Gas emissions decrease significantly during the high lava stand (the plume gets wispy, and resume during its draining phase. Taken together, the geophysical characteristics suggest that, during the high lava stand, lava is puffed up with gas trapped under the lava lake crust.

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).

pali: Hawaiian term for cliff or precipice.

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 which is, in turn, 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 160 m (525 ft) in diameter at the Halema`uma`u Crater floor, is about 50 m in diameter at a depth of 200 m (660 ft) below the Halema`uma`u Crater floor. From November, 2009, to now, a lava pond surface has been visible in 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.