May 6, 2010
A weekly feature provided by scientists at the Hawaiian Volcano Observatory.
Europeans wanted cash, not ash, from Iceland!
An Icelandic volcano was prominently featured in March and April's news, first for its gentle, tourist-friendly eruptions, and later for its catastrophic ash eruptions that shut down European air traffic for six days. The volcano's name, Eyjafjallaj?kull or Eyjafj?ll, doesn't easily roll off anyone's but Icelander's tongues.
Iceland, like Hawai`i, was created by volcanoes. Iceland is almost 10 times larger in area than Hawai`i Island, with twice as many people. In plate tectonic terms, Iceland was created by the coincidence of a hot spot and a spreading plate boundary, whereas Hawaiian volcanoes were produced by a hot spot beneath the middle of a plate, far from the nearest spreading boundary.
Eyjafjallaj?kull volcano is quite a bit smaller than Kīlauea—in length it would span the east rift zone from Pu`u `O`o to Cape Kumukahi—but is a bit taller in elevation. Eyjafjallaj?kull and its larger neighbor, Katla, are the southernmost volcanoes on the Icelandic mainland. Both have erupted historically.
The March eruption of Eyjafjallaj?kull volcano started on its eastern flank after months of inflation and heightened seismicity. Lava fountains up to 100m (330 ft) high played along a short fissure and fed thick `a`a lava flows that advanced only 1.6 km (1 mi) to the north. The longest flow created spectacular lava falls as it dropped through a steep canyon.
Iceland's initial Hawaiian-style eruption produced an average of about 13 cubic meters of lava per second (206,000 gpm) from its start on the evening of March 20 through a slow-down in activity on April 7. This average was about 3-5 times the typical long-term Kīlauea eruption rate but well below that of a typical Mauna Loa eruption. This phase of Eyjafjallaj?kull's eruption stopped on April 12, 2010.
Late on April 13, a swarm of small earthquakes began under the central part of Eyjafjallaj?kull, and an eruption at its ice-capped summit caldera was confirmed on April 14. This activity was much more explosive for two reasons: (1) the magma was more gas-rich than that erupted during the March flank event, and (2) hot lava rapidly melted the overlying ice cap, producing meltwater that flashed explosively into steam.
Cinder and ash were ejected high into the atmosphere and, by April 15, had been blown eastward, resulting in closures of most European airspace. Ingestion of volcanic ash into jet engines can foul critical parts and sensors, which can result in significant loss of power during flight—not a good thing. About 100,000 flights were cancelled and millions of passengers and cargo containers were stranded during the six-day closure.
Icelanders were, at first, happy about the potential boon to tourism created by the relatively safe flank eruption. The good publicity was welcome, given the bad publicity about the collapse of Iceland's economy in 2008. But the change in eruption styles eventually resulted in even more negative publicity as Iceland's ash spread over Europe.
During the first three days of the summit eruption, 10-20 times more lava was erupted than during the earlier flank event (this higher eruption rate was similar to Mauna Loa eruptions). By the fourth day, the eruption rate had diminished to less than 30 cubic meters per second (480,000 gpm). The threat of more regional ash dispersal will continue until Eyjafjallaj?kull's eruption stops as shown by activity in the past few days.
Local effects from its summit eruption were also profound. Lava from the summit craters melted its way beneath glaciers, creating significant flooding. Known as j?kullhlaups, these floods covered portions of the coastal plain west of the volcano, destroying roads, bridges, and farm buildings—losses that will be another blow to the Icelandic economy.
While Eyjafjallaj?kull has already caused many problems, there is even more to worry about. The two most recent eruptions of this volcano were closely associated with more intense eruptions of its larger neighbor, Katla. So far, Katla has shown no signs of activity.
Icelandic volcanological agencies are keeping a very close watch on both volcanoes. Detailed up to date information can be found online at http://www.earthice.hi.is/page/ies_Eyjafjallajokull_eruption?74, and an excellent sequence of photographs showing the range of activity described here can be viewed at http://www.earthice.hi.is/page/jardvis_eyjo_myndir
Kīlauea Activity Update
Breakouts, scattered from the top of the Pulama pali to the coast along the new eastern flow branch, were active throughout the past week. Lava, entering the ocean at the flow's terminus, is constructing a new lava delta near a long-buried promontory called Ki. Expansion of the flow on the coastal plain buried the County's viewing area by mid-week and had begun to consume the visitor parking area at the end of Highway 130. As of this writing (Thursday, May 6), the flows had crossed the end of the road and were creeping toward the ocean through thick vegetation, triggering small brush fires and minor methane bursts in the process. More of the highway pavement will likely get covered during the next few days.
At Kīlauea's summit, a ponded, circulating lava surface deep in the collapse pit within the floor of Halema`uma`u Crater was visible via Webcam throughout the past week. The lava surface remained relatively steady, showing little variation in its depth below the rim of the vent. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.
There were no felt earthquakes during the past week.
Visit our Web site (http://hvo.wr.usgs.gov) for detailed Kīlauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea activity summary; email questions to askHVO@usgs.gov.
Updated: May 28, 2010 (pnf)