February 5, 2009
A weekly feature provided by scientists at the Hawaiian Volcano Observatory.
Quiescence in 1913 is similar to 2008 events
In most sciences, processes are investigated by identifying the factors that affect them and varying each factor, in turn, to determine its contribution. In field geology, this is difficult; instead, we compare and contrast events or locations to learn more about the processes. At Kīlauea, there is a long, well-documented history with which to compare and contrast current activities. Summit events at Kīlauea over the last year have been unique since 1924, but bear interesting similarities to lulls in lava lake activity prior to 1924.
It is well known that, until 1924, there was a nearly continuous lake of lava in Halema`uma`u Crater, which was less than half the diameter it is today. But "nearly continuous" means there were periods when the lava lake disappeared. Mid-1913 to late 1914 was one of those periods when the crater was filled with fume, but not lava. Fortunately, regular Hawaiian Volcano Observatory (HVO) reports described this lull.
In 1913, HVO was located where the Volcano House hotel is today. Lacking direct views into Halema`uma`u Crater, observers noted sounds and characteristics of the fume coming from the pit to describe its behavior.
Reports of glow were infrequent, but descriptions of noises from the crate-blowing, coughing, booming, hissing, rumbling, grumbling, puffing, and breathing-were common. Rock slides, which were frequent and audible, sometimes produced dust clouds.
"During the last three months the only marks of activity which have fluctuated have been noises of blowing and rumbling, greater or less suffocating quality to the fumes when breathed, and very rare glimpses of flame seen two or three times at night." (HVO report, August 18, 1913).
Through September, the noises increased in intensity, and some glow was observed. Pele's hair was frequently found downwind of the crater and, when the fumes cleared, glimpses of a lava vent deep in Halema`uma`u Crater could be seen.
By October 20, 1913, Halema`uma`u Crater was considered to be in a minor eruptive phase. The crater was emitting much greater volumes of fume than in August. Sounds resembling "swashing liquid" suggest the continued existence of a lava lake, even when it was obscured by fume. A glow-lit fume cloud was a frequent sight over the crater at night.
Activity decreased through the end of 1913, and Halema`uma`u finished the year in a "semi-dormant" state, with a crater shaped like a huge funnel about 200 m (600 ft) deep and a thickly crusted lava pool in its bottom. Vigorous lava lake activity did not resume until late 1914.
Jump ahead to 2008. HVO reports have been describing many of the same characteristics. Few views of a lava pond have been recorded, but blowing and booming sounds, rock falls, and dust plumes have been common. Explosions were common in much of 2008, and some were energetic enough to erupt material to the crater rim.
The 1913-14 lull in activity and the currently elevated summit activity both result from lava being at similar shallow depths below Halema`uma`u Crater. In the early part of 1913, lava dropped to that level. In early 2008, magma rose to a similar depth.
The 2008 activity produced small amounts of tephra, often including Pele's hair. The 1913-14 lull also produced notable amounts of Pele's hair, but production of other tephra was not recorded.
Throughout both events, progress is highly variable. The overall rise of lava in the crater during 1913 and 1914 was halting, with episodes of rise repeatedly cut short with episodes of subsidence. Similarly, the 2008 activity changes several times a week, with lava interpreted to be rising and falling within the conduit below the vent.
In both cases, shallow magma produced elevated SO2 emissions and glow from the vent. "Fumes continue to pour out without abatement" (HVO report, February 4, 1914). Observers commonly described the fume as being difficult to breathe in 1913. Respiratory protection is required to work in the fume emitted today but probably wasn't necessary in earlier years.
HVO continues to monitor Kīlauea's activities and we hope to learn more by comparing recent events with past volcanic activity.
Kīlauea Volcano continues to be active. A vent in Halema`uma`u Crater is emitting elevated amounts of sulfur dioxide gas and producing small amounts of ash. Resulting high concentrations of sulfur dioxide in downwind air have closed the south part of Kīlauea caldera and produced occasional air quality alerts in more distant areas, such as Pahala and communities adjacent to Hawai`i Volcanoes National Park, during kona wind periods. A collapse deep within the vent on Wednesday, February 4 produced a robust brown plume and appeared to reopen the conduit, filled with rubble since early December. Views inside the vent the next day with a thermal camera showed a small, crusted lava pond more than 100 yards below the vent rim.
Pu`u `Ō`ō continues to produce sulfur dioxide at even higher rates than the vent in Halema`uma`u Crater. Trade winds tend to pool these emissions along the West Hawai`i coast, while Kona winds blow these emissions into communities to the north, such as Mountain View, Volcano, and Hilo.
Lava erupting from the Thanksgiving Eve Breakout (TEB) vent at the eastern base of Pu`u `Ō`ō continues to flow to the ocean at Waikupanaha through a well-established lava tube. Breakouts from a western branch of the lava tube were active on the coastal plain near the National Park boundary early in the week and also continued to feed the small ocean entry near Waha`ula. A deflation-inflation cycle beginning February 3 led to a short-term reduction in lava supply to the flow field. Surface flows and ocean entries were inactive on Thursday, February 5, and will probably resume shortly.
Be aware that active lava deltas can collapse at any time, potentially generating large explosions. This may be especially true during times of rapidly changing lava supply conditions. The Waikupanaha delta has collapsed many times over the last several months, with three of the collapses resulting in rock blasts that tossed television-sized rocks up onto the sea-cliff and threw fist-sized rocks more than 200 yards inland.
Do not approach the ocean entry or venture onto the lava deltas. Even the intervening beaches are susceptible to large waves generated during delta collapse; avoid these beaches. In addition, steam plumes rising from ocean entries are highly acidic and laced with glass particles. Call Hawai`i County Civil Defense at 961-8093 for viewing hours.
Mauna Loa is not erupting. No earthquakes were located beneath the summit this past week. Continuing extension between locations spanning the summit indicates slow inflation of the volcano, combined with slow eastward slippage of its east flank.
Three earthquakes beneath Hawai`i Island were reported felt within the past week. A magnitude-3.2 earthquake occurred at 3:37 p.m., H.s.t., on Friday, January 30, 2009, and was located 2 km (1 mile) east of Pahala at a depth of 10 km (6 miles). A magnitude-3.4 and a magnitude-3.5 earthquake occurred at 7:12 and 7:17 p.m., respectively, on the same Friday and were located 7 km (4 miles) west of Kalapana at a depth of 9 km (6 miles).
Visit our Web site (http://hvo.wr.usgs.gov) for daily Kīlauea eruption updates, a summary of volcanic events over the past year, and nearly real-time Hawai`i earthquake information. Kīlauea daily update summaries are also available by phone at (808) 967-8862. Questions can be emailed to askHVO@usgs.gov.
Updated: February 11, 2009 (pnf)