HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
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: A second DI deflation started at midnight while the lava lake level fluctuated. Seismic activity increased in the upper east rift zone. At Pu`u `O`o, short lava flows issued from the NE pit and south sources; the lava lake in the NE pit remained active with spattering visible from the sources along the north and south crater floor edges. Lava flows southeast of Pu`u `O`o continued to be weakly active on the coastal plain. Seismic tremor levels were low, and gas emissions were elevated.
Recent Observations at Kilauea summit: Back-to-back DI events have halted the slow upward rise of the lava lake. DI inflation started around 5 am yesterday and was followed by a second DI deflation at midnight last night. Changes in the lava lake level due to the DI events were masked by the continuing rise/fall events. The inner ledge continued to be submerged during the rise part of rise/fall events and it showed evidence of slumping at least its shallowest layers into the lava lake yesterday changing the shape of the ledge edge.
The most recent (preliminary) sulfur dioxide emission rate measurement was 700 tonnes/day on October 22, 2012; measurements will resume with the return of moderate trade winds. Although not measured today, a small amount of ash-sized tephra (mostly fresh spatter bits and Pele’s hair, but also bits of the vent wall) was probably carried out of the vent in the gas plume and deposited on nearby surfaces. Cracking noises, sometimes audible from the Jaggar overlook and caused by rocks of the vent wall fracturing from the heat, emanate sporadically from the vent.
The GPS network continued recording extension across the summit caldera at the rate of about 1 cm/wk since the beginning of October. Seismic tremor levels remained generally low (variable during rise/fall events) and upper east rift zone seismicity continued to increase. Forty-five earthquakes were strong enough to be located beneath Kilauea: 5 west and south of the summit caldera, 32 within the upper east rift zone (centered beneath Puhimau Crater), 2 in the vicinity of the middle east rift zone, and 6 on south flank faults.
Background: The summit lava lake is deep 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 fluctuates from about 40 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. Most recently, the surface level of the lava lake has remained below an inner ledge (~50 m or 165 ft below the floor of Halema`uma`u Crater on October 9, 2012), sometimes rising to flood the ledge. 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: Surface flows continued weak activity within the abandoned Royal Gardens subdivision, with flows extending seaward across the coastal plain. These flows have not advanced much over the past week, and are about 1.4 km (0.9 miles) from the coast based on position estimates from webcams. Minor flow activity also continued on the pali.
At Pu`u `O`o, activity remained elevated. A short lava flow issued from one of the sources on the south edge of the crater floor just after noon yesterday and two short flows issued from both the northeast pit and the same south source between 1 and 3 am this morning. The perched lava lake within the northeastern pit remained active and spattering was recorded from sources at the south and north edges of the crater floor.
The tiltmeter on the north flank of Pu`u `O`o cone recorded probable DI events at delays that were getting progressively shorter with time: Friday’s summit DI deflation was recorded at 4 am yesterday (17 hour delay), DI inflation was recorded at noon (7 hour delay), and the current DI deflation was recorded at 2 am this morning (2 hour delay). GPS receivers spanning the Pu`u `O`o crater continued to record extension rates of about 0.5 cm/wk since the beginning of October. Seismic tremor levels near Pu`u `O`o increased slightly. The most recent (preliminary) sulfur dioxide emission rate measurement was 200 tonnes/day on October 22, 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 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 that advanced southeast through the abandoned Royal Gardens subdivision to the ocean within Hawai`i Volcanoes National Park in early December. Since late December, the flows have remained intermittently active on the pali and the coastal plain but have not entered the ocean. 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 – The new breakout lava flows were 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, glow from these flows may be reflected in clouds which can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093). Pu`u `O`o Cone, the strip of coastal plain nearest the ocean, 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.
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:
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).
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 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.