While the after effects of the volcano Eyjafjallajokull are slowly beginning to dissipate, scientists warn that the new worry surrounds the adjacent and massive Katla volcano. Eyjafjallajokull has served as the opening act or at the least a contributing trigger for Katla three times in succession in the past.
The Katla volcano, located near the southern end of the islands eastern volcanic zone, hidden beneath the Myrdalsjökull icecap, is one of Iceland's most active and is a frequent producer of damaging jökulhlaups, or glacier-outburst floods. A large 9 x 14 kilometer subglacial caldera is up to 750 m deep.
Although most historical eruptions have taken place from fissures inside the caldera, the Eldgjá fissure system, which extends about 60 km to the northeast from the current ice margin, has been the source of major Holocene epoch eruptions. An eruption from the Eldgjá fissure system about 934 AD produced a voluminous lava flow of about 18 cu km, one of the world's largest known lava flows. Katla has been the source of frequent explosive eruptions.
The volcano Katla, if triggered, could pose a far more serious threat, as much as ten times stronger than what was just experienced with Eyjafjallajokull with stronger tremors and more lava of course, but also a much larger ash plume.
The two volcanoes are only separated by approximately 12 miles above ground, but geologists believe that beneath the surface they are linked by a series of shared magma channels which is why they so often erupt in relative unison. Like Eyjafjallajokull, Katla is buried beneath Myrdalsjokull which is among the largest glaciers in Iceland, estimated to be about 550 yards deep, or twice as thick as the glacier over Eyjafjallajokull was prior to the eruption.
The last three times Eyjafjallajokull erupted, Katla followed suit. To make matters more acute, Katla erupts about every 80 years on average, the last time being in 1918.
At this time seismic readings show that there have been small tremors at Katla, but geologists and geophysicists believe these are not indicators of an eruption, but rather the after effects of Eyjafjallajokull that triggered glacial displacement and are slightly skewing sensors causing false positive readings. While there is no fear of an imminent threat from a Katla eruption as Katla could erupt tomorrow or hold off another 1, 5, or 20 years.
Casey Kazan via AP News
Image credit: www.guardian.co.uk/environment/blog/2010/apr