reply to post by Ptolomeo
Recent Kilauea Status Reports, Updates, and Information Releases
HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
Thursday, April 28, 2011 7:32 AM HST (Thursday, April 28, 2011 17:32 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
www.nps.gov... or 985-6000.
Hawai`i County Kalapana Viewing Area status can be found at 961-8093. 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: The summit lava lake level remained stable with variations. In the east rift zone, vents at the base of the east
crater wall filled a lake abandoned by the vent that formed it in the Pu`u `O`o crater floor. Seismicity levels and gas emission rates remained
generally low.
Past 24 hours at Kilauea summit: The summit tiltmeter network recorded continuing DI deflation; the summit lava lake level dropped slightly deep in
the vent inset within the east wall of Halema`uma`u Crater.
Seismic tremor levels were low and steady. The summit GPS network recorded long-term extension. Seven earthquakes were strong enough to be located
beneath Kilauea volcano on south flank faults.
The gas plume is moving to the southwest this morning. The most recent (preliminary) sulfur dioxide emission rate measurement was 400 tonnes/day on
April 24, 2011. Barely measurable amounts of ash-sized tephra continued to be wafted in the plume and deposited on nearby surfaces.
Past 24 hours at the middle east rift zone vents: Lava filled a new lake from sources at the west end of the lake and also along the base of the east
crater wall; by evening, only the east sources were erupting lava that poured into the lake that is roughly centered on the Pu`u `O`o crater floor.
There was no molten lava present in the east rift zone outside Pu`u `O`o crater.
The tiltmeter on the north flank of Pu`u `o`o Cone recorded continued deflation. The GPS network around Pu`u `O`o recorded neither extension nor
contraction since late March. Seismic tremor levels near middle east rift zone vents remained variable at low values. The most recent (preliminary)
sulfur dioxide emission rate measurement was 100 tonnes/day on April 24, 2011 from all east rift zone sources.
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. Kilauea Crater - explosive
events are capable of ejecting rocks and lava several hundred meters (yards) from the Halema`uma`u vent; ash and Pele's hair can be carried several
kilometers downwind; potentially-lethal concentrations of sulfur dioxide can be present within 1 km downwind.
Maps, photos, Webcam views, and other information about Kilauea Volcano are available at
volcanoes.usgs.gov... 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
tux.wr.usgs.gov...
A definition of alert levels can be found at
volcanoes.usgs.gov...
Definitions of Terms Used:
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 structure was the lava channel that was active between July and November, 2007; flowing lava slowly built levees 50 m high
that confined the lava flowing through the mile-long channel.
mauka, makai: Hawaiian terms for directions relative to the coast - makai (toward the coast) and mauka (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
volcanoes.usgs.gov...
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 Hawaii
Link to full story .
Link to Hawaiian vebcams