Icelandic eruption and ash fall: Disaster response, take two

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On May 21, 2011, Grímsvötn volcano awoke from a 7-year eruptive slumber, producing an ash and gas plume about 17 km (10.6 miles) high. The eruption brought on immediate concern that airline traffic would be disrupted in Europe for the second time in as many years.

The initial eruptive plume rose higher than that of Eiya (Eyjafjallajökull) in 2010, and higher than Grímsvötn's last eruption in 2004. Within hours, ash began to blanket areas within Iceland 50 miles southeast of the volcano. In response, airports in Iceland were immediately closed to international traffic while the UK and the European continent prepared for the worst.

Grímsvötn is Iceland's most active volcano, erupting about once every 10 years since 1783, when it and its neighbor, Laki fissure, erupted catastrophically. Together in that year, the ash and gas produced by these two eruptions caused widespread famine and the deaths of about 20 percent of Iceland's population.

Within a year of the 1783 eruptions, 60 percent of Iceland's grazing livestock also died from ash ingestion and associated fluorosis. Widespread reports of the eruption's environmental impact—sulfurous odor and burned vegetation (never mind about air traffic problems)—occurred in Europe.

The 2011 Grímsvötn eruption was not a total surprise. In addition to the volcano's frequent eruptive history, Icelandic volcanologists had been monitoring continuous inflation of the volcano since 2004. Increased geothermal activity and, more recently, seismicity, including tremor bursts, had also told them that something was up.

Icelanders have learned to live with their volcanoes the way we live with ours here in Hawai‘i: respectfully. Especially recently, Europeans are adjusting their lives and activities to be more respectful, as well.

Last year's spectacular eruption of Eiya renewed the resolve amongst European geologists who study volcanic hazards, like ash, meteorologists who work to predict where ash might be transported, and civil aviation authorities who are charged with keeping airliners safe. Until that event, though, commercial airline companies and engine manufacturers, who are necessarily watchful of profit margins, were less than enthusiastic participants in volcanic disaster preparedness.

The cancellation of an estimated 95,000 flights by civil aviation authorities for the 2010 eruption motivated airline and aircraft companies to conduct more detailed studies of the tolerance of jet engines to volcanic ash. Until that time, regulations mandated a zero tolerance policy in airspace that was forecast to contain ash.

The enhanced testing and agreement of the airlines, aircraft companies, and civil aviation authorities and governments allowed the opening of limited fly zones. The new designation carefully permits airlines to fly where airborne ash concentration is forecast to be less than 4 milligrams/cubic meter.

For Europeans concerned about ash from Icelandic eruptions, the success of this new bit of regulation relies heavily on the accuracy of ash distribution forecast maps produced by the UK's Volcanic Ash Advisory Center's (VAAC).

The mapped information and European airspace decisions are coordinated amongst 39 member states and the European community by an organization called Eurocontrol. Following the Eiya eruption in 2010, Eurocontrol and the UK's VAAC have worked carefully together to plan for possible future eruptive scenarios.

Remarkably, barely a month before the 2011 Grímsvötn eruption began, Eurocontrol and the UK Ash Center, along with the freshly galvanized community of nearly 100 airlines, regulatory authorities, and air navigation companies, carried out a crisis exercise to test and validate the regulatory changes and procedures.

And what volcano did they choose to carry out their exercise on, you ask? Why, Grímsvötn, of course! The scenario played out a fictitious 48-hour eruption of the volcano, complete with an ash plume to 10 km (30,000 ft) and forecast winds that took the plume across the UK and the European continent.

One member of the USGS Volcano Science Center and former HVO staffer who attended the exercise applauded its success but noted the spookiness of hearing of the real eruption of Grímsvötn just a month later.

As of this writing (Thursday, 26 May), activity has diminished, and the eruption appears paused. The European community in general, and hopeful commuters in particular, are breathing a guardedly optimistic sigh of relief. What appears clear at this time is that the lessons learned from the Eiya eruptive crisis a year ago have paid off in spades for the current one.

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Volcano Activity Update

Lava erupted continuously within Pu‘u ‘Ō‘ō over the past week, feeding a lava lake perched above the crater floor. Changes in eruptive output commonly resulted in overflows from the lake that slowly built up the crater floor, which is about 35 m (115 ft) below the east rim of Pu‘u ‘Ō‘ō. No lava is erupting outside the crater.

A small lava lake was also present deep within the Halema‘uma‘u Overlook vent during the past week. On May 25, the lava lake rose abruptly to a new level 120 m (394 ft) below the floor of Halema‘uma‘u. Volcanic gas emissions remain elevated, resulting in relatively high concentrations of sulfur dioxide downwind.

One earthquake beneath Hawai‘i Island was reported felt this past week. A magnitude-3.0 earthquake occurred at 6:45 p.m., HST, on Friday, May 20, 2011, and was located 17 km (11 mi) southeast of Ho‘okena at a depth of 10 km (6 mi).