HAWAIIAN VOLCANO OBSERVATORY DAILY UPDATE
Saturday, March 29, 2008 07:19 HST
(Saturday, March 29, 2008 17:19 UTC)

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, in addition to maps, photos, and webcam images (available using the menu bar above), was prepared by the Hawaiian Volcano Observatory (HVO):

Activity Summary for last 24 hours: Kilauea Volcano is active at two locations. At the summit, the Halema`uma`u vent continued erupting ash and switching to a white plume just before 3 pm. Sulfur dioxide emission rates and seismic tremor levels continued elevated to several times background levels. At the coast, lava continued to flow into the ocean at the Waikupanaha and Ki ocean entries. The east margin of the flow field was active in two spots makai of the road.

Hazard Summary: Hazardous conditions exist in the summit area and the area between the rift zone (Pu`u `O`o to Kupaianaha) downslope to the ocean between Kalapana and Kapa`ahu.

1. Summit: The current increase in sulfur dioxide emission rates at the summit means that SO2 concentrations in the air are likely to be at hazardous levels for areas downwind of emission sources in Halema`uma`u crater. The National Park Service has closed Crater Rim Drive through the south caldera area until further notice (http://www.nps.gov/havo/closed_areas.htm). Most people are sensitive to sulfur dioxide at these levels. Children and individuals with asthma, chronic obstructive pulmonary disease (COPD), or other breathing problems especially should avoid downwind areas. During tradewind conditions (brisk winds from the northeast), concentrations will be highest and most hazardous in the south caldera: southwest rift zone, south caldera pullouts, and the Halema`uma`u overlook parking lot - The National Park Service has closed this section of Crater Rim Drive. During weak or southerly winds, concentrations may be high and hazardous throughout the summit area of Hawai`i Volcanoes National Park and nearby communities. Stay informed about SO2 concentrations in continuously monitored areas at Jaggar Museum and Kilauea Visitor Center (http:// www.nature.nps.gov/air/webcams/parks/havoso2alert/havoalert.cfm).

The gas plume also includes fine rock dust downwind of the source. During the past few days, several people have reported a fine grit on their car windshields while driving under or in the ash plume along highway 11 and as far away as South Point. Information on the effects of ash are available at http://www.ivhhn.org/ and http://volcanoes.usgs.gov/ash/.

The possibility of future small explosions or eruption of lava from Halema`uma`u Crater cannot be ruled out.

2. Pu`u `O`o/July 21/TEB flow field: Vent areas and lava channels are hazardous and conditions can change rapidly. Sulfur dioxide emissions from Pu`u `O`o are high and result in hazardous concentrations downwind. Access to the 7/21 eruption site in the Kahauale`a Natural Area Reserve is closed (see http://www.state.hi.us/dlnr/chair/pio/HtmlNR/07-N076.htm). Wao Kele o Puna is also closed.

There continues to be a threat from lava flows to anyone within Royal Gardens subdivision and the coastal plain. As long as lava flows are active south of fissure D, the subdivision is within likely paths of future flows. The rootless shields, which are now less than two miles from the subdivision, can collapse and release lava flows that advance that distance within a few days. Tube- or channel-fed lava flows established within the subdivision and on the coastal plain remain a threat due to tube ruptures which can produce new lava flows. Lava flows advancing through vegetation are hazardous and can produce fire and methane explosions that propel chunks of lava and rock several feet into the air. Hawai`i County Civil Defense has been notified and is taking appropriate measures (www.lavainfo.us).

Lava entering the ocean poses two additional hazards - potential collapse and laze. Lava entering the ocean builds a delta over its own rubble that is extremely unstable. That delta can collapse without warning and expose very hot surfaces to waves which can explode and throw rock debris up to one-quarter mile inland. For these reason, spectators should avoid the delta and the area one-quarter mile inland. The interaction between seawater and lava produces a steam plume laced with acids and fine particles of volcanic glass or \'laze\' that is unhealthy if inhaled and can produce skin or eye irritation if contacted. Hawai`i County continues to open a public viewing area between 2 and 10 pm with the last car allowed in at 8 pm. For details, see www.lavainfo.us or call 961-8093.

TEB lava flows at the coast as of yesterday evening (from combined HVO and NPS eruption crew reports): Lava continued to flow into the ocean at 3 points on the Waikupanaha and Ki ocean entries. A long crack across the east portion of the Waikupanaha delta may indicate potential collapse; small pieces were reported breaking off yesterday evening. The eastern flow field margin was active at two locations makai of the access road producing some burning yesterday evening.

Last 24 hours at the Pu`u `O`o/TEB vent area: Incandescence was again seen from the TEB vent but not from the rootless shields or from the upper flow field. HVO geologists yesterday found no surface flows active other than a patch on the Kalalua flow and small breakouts on the coastal plain. The lava tube system seems, for the moment, to be stable and transporting lava efficiently to the ocean entries.

Diffuse but weak incandescence was observed overnight in Pu`u `O`o crater by webcam. The tiltmeter recorded weak deflation of the Pu`u `O`o/TEB vent over the past week. GPS receivers on opposite sides of the crater continued to record contraction at a rate averaging 2 cm/month over the past 3 months. Seismic tremor levels were at low values. The SO2 emission rate was about 2,500 tonnes/day on March 27.

Last 24 hours at Kilauea summit: Eruption of ash continued with a switch to a white plume just before 3 pm yesterday. Further analysis of ash fall data during the 3/27 white plume period showed that ash production did not diminish as was first thought. Instead, it appeared that the ash in the white plume contained more volcanic glass than ash from a brown plume. There were no new explosions. The base of the plume glowed dimly and incandescent fragments were ejected sporadically. Seismic tremor levels increased slightly when the plume turned to white. The summit tiltmeter network recorded no tilt signal above typical daily oscillations. Two small earthquakes were located beneath an area immediately to the east of Halema`uma`u Crater and one was located on south flank faults.

The sulfur dioxide (SO2) emission rate from the summit continued to be elevated and was about 750-830 tonnes/day on Mar. 27 (measured twice,), compared to a background rate of between 150-200 tonnes/day. The reduced emissions were obtained on the white plume and are expected to increase with the resumption of the brown plume as has been observed earlier this week.

Sulfur dioxide concentrations were again below concern at Jaggar museum and Kilauea Visitors Center. Trade (northeasterly) winds kept gas emissions in the south caldera where SO2 concentrations were up to 40 ppm in areas downwind of Halema`uma`u Crater along Crater Rim Drive (mostly between Halema`uma`u parking lot and the southwest rift zone pullout during trade winds) and up to 140 ppm near the Halema`uma`u overlook close to the new vent.

Definitions of terms used in the update:

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

mauka, makai: Hawaiian terms for the direction toward the mountains and toward the ocean, respectively.

incandescence: the production of visible light 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).

TEB: The most recent phase of activity started with a breakout from the perched channel/pond system on November 21, 2007 or Thanksgiving eve. TEB stands for Thanksgiving Eve Breakout.

kipuka: a Hawaiian word which describes an area of vegetation that is completely surrounded by active or inactive lava flows.

NPS eruption crew: a hardy band of experienced individuals who interpret active lava flow viewing for visitors while keeping them at a safe distance. The National Park Service (NPS) eruption crews normally work within the Hawai`i Volcanoes National Park but have been supporting the Hawai`i County lava viewing effort since it opened on Saturday, March 8, 2008.

rootless shields: Shield vents are normally built directly over a lava-supplying fissure, as is the case for the TEB shield. Rootless shield vents are not built directly over a lava-supplying fissure and are, instead, fed horizontally from a fissure via a lava tube. Rootless shields have been built over Kilauea lava tubes in the last few years.

perched ponds or channels: A lava pond or channel becomes perched above the surrounding terrain when repeated overflows build up their edges. The perching continues as long as the overflows continue. The channel developed by the July 21, 2007 eruption perched itself more than 100 feet above the pre-eruption ground surface.

gas emission rates: usually in metric tonnes (= 1,000 kilograms)/day if measured at HVO, a gas emission rate is the rate at which gas is released by a volcanic vent. Typical background SO2 emission rates for Kilauea are 150-200 tonnes/day from sources in Halema`uma`u crater and 1,500-3,000 tonnes/day from Pu`u `O`o vent. Once the gas is released into the air, the hazard it poses to living things is directly related to its concentration. Higher concentrations are found downwind of sources so changes in wind direction and speed can bring gases at hazardous concentrations into different areas.

LP earthquakes: Most volcanic earthquakes that occur in Hawai`i are short-period (SP) in nature, meaning that the shaking starts abruptly and contains relatively high frequency components; these quakes are usually associated with subsurface rock failure (breakage). Long-period (LP) earthquakes have lower frequency energy and emergent beginnings, meaning that their signals start with small amplitude and become stronger. LP earthquakes are usually associated with subsurface fluid movement.

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 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/hvostatus.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