Volcano Update from Archive



HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
Monday, April 7, 2014 7:32 AM HST (Monday, April 7, 2014 17:32 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). All times are Hawai`i Standard Time.

KILAUEA VOLCANO (VNUM #332010)
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: The eruption continued at the summit and within the east rift zone with no significant changes. The summit tiltmeter network recorded weak inflationary tilt while the summit lava-lake level fluctuated but remained fairly steady. A seismic swarm continued beneath the south summit caldera. At the middle east rift zone, the Pu`u `O`o vent continued feeding the Kahauale`a 2 lava flow whose distal end remained active in webcam views. Gas emissions remained elevated.

Recent Observations at Kilauea summit: The summit tiltmeters recorded continuing weak inflationary tilt (less than 0.5 microradians over the past day). The lava-lake level fluctuated but remained at about 44 m (144 ft) below the floor of Halema`uma`u crater. Gas emissions continued to be elevated: during the week ending on 03/25/14, the summit SO2 emission rate varied between 3,800 and 6,300 tonnes/day (see caveat below); the ambient SO2 concentrations near the vent vary greatly and can exceed 50 ppm. The gas plume typically included a small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair from the circulating lava lake); the heaviest pieces are deposited onto nearby surfaces while the finer bits can be carried several kilometers before dropping out of the plume.

Seismic tremor levels were low and variable with several dropouts. Thirty-eight earthquakes were strong enough to be located beneath Kilauea Volcano in the past 24 hours: 15 scattered along the south flank faults, 13 beneath the area extending from Halema`uma`u Crater to a few kilometers to the south (swarm day 10), 6 within and adjacent to the upper east rift zone, and the rest scattered in the Ka`oiki Pali area, the lower southwest rift zone, and northeast of the summit. GPS receivers spanning the summit caldera recorded changes mimicking the recent tilt changes after recording about 3 cm of extension between early December, 2013, and mid-February, 2014; the long-term, cross-caldera measurements indicate continued extension at a rate averaging 10 cm/yr (4 in/yr) since March, 2010.

Background: The summit lava lake is within a nearly-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 minor fluctuations. The most recent sulfur-dioxide emission-rate measurement was 200 tonnes per day on March 24, 2014, from all east rift zone sources; emission rates typically ranged between 150 and 450 t/d since July 2012. GPS receivers on the north rim and south flank of Pu`u `O`o cone recorded fluctuations mimicking the tilt changes while also recording extension at a rate of about 1 cm/month. The Pu`u `O`o eruption continued with no significant changes. Spatter cones on the floor of Pu`u `O`o crater displayed persistent glow with a circulating lava pond within the collapsed northeast spatter cone (see images and video).

Recent Observations of the Kahauale`a 2 flow: The northeast spatter-cone complex continued to feed the Kahauale`a 2 lava flow. A March 27th satellite image showed active breakouts 5.5-8.0 km (3.4-5.0 mi) northeast from Pu`u `O`o; this is the farthest advance of the Kahauale`a 2 lava flow since the March 21st mapping by HVO geologists when the flow extended 8.2 km (5.1 mi) northeast of Pu`u `O`o before apparently stalling at the front. PNcam views confirmed that the flow is still active at several locations along the front this morning. An overflight by HVO geologists is planned for later this morning if the weather remains clear.

In general, this slow-moving lava flow has made erratic progress over the past few months. Disruption of the flow front has occurred during strong DI deflation events when the lava supply abruptly decreased causing the flow front to stagnate. DI inflation and resumption of lava supply usually follow a few days later. Breakouts reappear well behind the stalled flow front and take some time to reach the front again. In this way, the flow front has not advanced more than 1.2 km (0.75 mi) since the first time it stalled in early November, 2013.

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. The flows stalled and re-entered the ocean starting on November 24, 2012 until activity started to decline and the ocean entry ceased in August 20, 2013; the flow was dead by early November, 2013. 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 (informally called 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 - the Kahauale`a 2 flow does not pose any immediate threat to residential areas; 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. Active lava flows within forest can produce methane blasts that propel rocks and other debris into the air. 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 or the Office of Hawaiian Affairs. 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) or the Wao Kele o Puna Forest Reserve (DLNR, OHA) and can only be viewed from the air. Under favorable weather conditions at night, distant glow from the active flows 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.

Sulfur Dioxide Emission Rate estimation caveat: Starting in 2014, we report the emission rate estimated by a new, more accurate method. The numbers increase by a factor of 2-4 but the actual emission rate has not changed. For more on this reporting change, please read http://hvo.wr.usgs.gov/volcanowatch/view.php?id=207

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:

LPs - Long Period (LP) events refer to earthquakes that have a lower frequency or tone than typical earthquakes and are usually attributed to the resonance of fluid- and gas-filled conduits, cracks and/or chambers. Because of their association with fluids and gases, LP earthquakes in the vicinity of volcanoes can be useful for monitoring purposes. At other volcanoes LP earthquakes are also known as low-frequency earthquakes, tornillos or B-type earthquakes.

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.

seismic tremor dropout: these behaviors are identical to rise/fall events except that the lava lake level doesn't rise or fall significantly. High-frequency seismic tremor, gas emissions, and spattering decrease abruptly during a dropout. A dropout can end with a burst of seismic tremor and a significant pulse of gas emissions.

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 0.984 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.