Volcano Watch — Amid Financial Turmoil, Kīlauea's "Budget" Appears Sound but the Forecast is Voggy

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If we think of volcanoes operating on a magma-based economy, the past several years have been remarkably profitable for Kīlauea. Normally, the Hawaiian Hotspot "bank" regularly pays the volcano in magma, which Kīlauea stores in a reservoir (like a wallet or purse) beneath the summit. Until 2003, Kīlauea's reservoir of magma was being spent faster-erupting on the East Rift Zone-than it was being resupplied from the "bank" and the volcano's wallet was getting thinner.

Between late 2003 through 2005, a windfall bonus of magma from the Hawaiian Hotspot "bank" was paid to Kīlauea's shallow summit reservoir. The infusion became apparent when, after more than five years of steady deflation or wallet thinning, the summit of the volcano began to swell.

By the beginning of 2005, the summit magma wallet was bursting at its seams, and an eruptive spending spree began. Lava production at Pu`u `Ō`ō increased significantly. After declining slightly, it remained nevertheless steady and significantly elevated for a year-and-a-half.

But we could tell that magma still wasn't being spent from the summit account as fast as it was being deposited. The summit reservoir continued to swell until June 17, 2007, when a large magma withdrawal occurred from both the summit and the east rift zone, including Pu`u `Ō`ō. The resulting expenditure to the surface produced Father's Day flows emplaced near Kane Nui o Hamo and temporarily unsettled Kīlauea's shallow plumbing.

Kīlauea's magmatic spending spree continued, though, rapidly refilling and finally bursting Pu`u `Ō`ō crater's seams. This was followed by the never-before-documented lava channel and ponds of late 2007, the Thanksgiving Eve Breakout (TEB) shield, subsequent rootless shields, and an expanded flow field to the coast. Then the expansion of Kīlauea's summit slowed and gently reversed.

The destabilizing magmatic supply-and-demand events of 2003-2007 produced other results, as well. Beginning in late 2007 and early 2008, Kīlauea summit tremor and SO₂ release ramped up to levels we hadn't seen in nearly 30 years of monitoring. Something literally was up. SO₂ release is a shallow process, magmatically speaking, and the increase in emissions told us that pressure confining SO₂ trapped in the magma below was lessening. By mid-February, SO₂ emissions were high enough to produce hazardous concentrations directly downwind of Halema`uma`u, prompting the park to close part of Crater Rim Drive. By March 12, gas worked its way to the surface, bursting through the east wall of Halema`uma`u.

Since March at least (some would argue sooner) Kīlauea has been spending its magmatic- and, particularly, its gas -budget, through two eruptive sites: the summit and the east rift zone. In July, a brief surge in effusion rate and east rift SO₂ emissions caused air quality in downwind communities, particularly in Pahala, to deteriorate even more.

Meanwhile, summit SO₂ emissions have remained seriously elevated, and-combined with about twice this amount of east rift gas release-add up to a total SO₂ release rate, beginning 2008, of 3,500 tonnes/day-nearly twice the average rate of the previous 5 years.

As we enter the cooler, wetter months encompassing Ho`oilo-October through April-residents and visitors to east Hawai`i can expect more frequent trade-wind disruptions. And with these disruptions will likely come more periods of poor air quality. This likelihood combined with the elevated emissions from summit and rift, tells us that we should brace ourselves for the voggy days to come.

The eruptive events of 2007 and 2008, especially, have clearly produced some remarkable and beautiful eruptive treasures, courtesy of Kīlauea's 2003-2006 windfall magma profit-a spectacular summit eruption and equally amazing surface flows and ocean entry. Nevertheless, as that familiar saying of economics goes, "There is no free lunch." Residents of east Hawai`i, who have been able to profit from views close to the eruption will be paying their vog dues in the coming months, giving those in west Hawa`ii a few days' respite.

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Volcano Activity Update

Kīlauea Volcano continues to be active. A vent in Halema`uma`u Crater is erupting elevated amounts of sulfur dioxide gas and very 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. On October 9, scientists got another look at the lava lake deep within the vent on the floor of Halema`uma`u. The lava lake, barely visible from the air, appeared to be approximately 120 to 150 meters (about 400 to 500 ft) below the vent rim, and cannot be seen from the rim of Halema`uma`u Crater or Jaggar Museum Overlook. There have also been several small ash-emission events from the vent, lasting only minutes, in the last week.

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 continues to erupt from fissure D of the July 21, 2007, eruption and flows toward the ocean through a well-established lava tube. A deflation-inflation cycle at the summit created fluctuations in activity at the flow field over the past week. The deflation phase of the cycle produced a pause in activity at the flow field and ocean entry, lasting several days, due to a reduction in lava supply. The inflation phase of the cycle led to an increase in lava supply that created breakouts from the lava tube starting on Monday, October 6. As of Thursday (Oct 9) three moderate-sized surface flows were still active in and above Royal Gardens subdivision, creating minor expansion of the flow field's east margin. The ocean entry at Waikupanaha had restarted by Wednesday (Oct 8) morning, and is producing a weak to moderate plume.

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. Do not 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. Check Civil Defense Web site or call 961-8093 for viewing hours.

Mauna Loa is not erupting. Three earthquakes were located beneath the summit this past week. Continuing extension between locations spanning the summit indicates slow inflation of the volcano.

One earthquake beneath Hawai`i Island was reported felt within the past week. A magnitude-2.7 earthquake occurred at 8:37 a.m., H.s.t., on Saturday, October 4, 2008, and was located 10 km (6 miles) northwest of Pahala at a depth of 10 km (6 miles).

Visit our Web site 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. skip past bottom navigational bar