Monday, July 23, 2012

Small Earthquake Swarm at Krafla Volcano, Iceland

Iceland

A series of small quakes has occurred at Krafla volcano in Northern Iceland. A series of about 10-12 small quakes, the strongest being near mag 1.5, occurred swiftly with maybe one or two very small aftershocks in the area. Krafla volcano last erupted in 1984 in a series of fissure fed events, and multiple inflation and deflation events. It is one of Iceland's most active volcanoes alongside Grimsvötn (or Grimsnes), Hekla, and Katla.

The depths of these events are unknown according to my computer analysis, but I suspect these quakes may have occurred due to geothermal prospects int he area, however this could also be related to a very minor dike intrusion under the volcano, as the locations of these quakes seem to suggest activity in the center of the topographically indistinct caldera region.

The Smithsonian GVP characterizes Krafla:

"The Krafla central volcano, located NE of Myvatn lake, is a topographically indistinct 10-km-wide caldera that is cut by a N-S-trending fissure system. Eruption of a rhyolitic welded tuff about 100,000 years ago was associated with formation of the caldera. Krafla has been the source of many rifting and eruptive events during the Holocene, including two in historical time, during 1724-29 and 1975-84. The prominent Hverfjall and Ludent tuff rings east of Myvatn were erupted along the 100-km-long fissure system, which extends as far as the north coast of Iceland. Iceland's renowned Myvatn lake formed during the eruption of the older Laxarhraun lava flow from the Ketildyngja shield volcano of the Fremrinamur volcanic system about 3800 years before present (BP); its present shape is constrained by the roughly 2000 years BP younger Laxarhraun lava flow from the Krafla volcanic system. The abundant pseudocraters that form a prominent part of the Myvatn landscape were created when the younger Laxarhraun lava flow entered the lake."

Krafla is highly active, geothermally speaking. It boasts many fumeroles, mud pots, and fissure systems. The last eruption began in 1974, and ended in 1984, a 10-year cycle that produced massive amounts of magma. Eruptions from Krafla today would likely not produce massive amounts of ash, rather it would most likely be a repeat of the previous eruption with fissure fed lava flows, and flood basalts that would no doubt produce a large amount of CO2/SO2 emissions, but otherwise be largely undamaging to populations near and around the world. One casualty, if the volcano should erupt, would most likely be the loss of geothermal prospecting in the area, which could also be the main cause of the recent quakes.

Personally, I would not be very worried about an eruption from Krafla, but I would be very excited to see it happen. These fissure eruptions do not occur worldwide very often, with the exception of Kilauea in Hawaii, and some volcanoes in the Great African Rift Valley, so an eruption like that would produce some very spectacular pictures and video indeed!

Iceland is always a fascinating place to keep an eye on. Even when volcanoes are not erupting, there are always plenty of volcanic-related things to see such as the famed Blue Lagoon, and the newly opened Thrihnukagigur volcano tour, where you are actually lowered into an extinct (or dormant) volcano's magma chamber! Not to mention the famed Hekla volcano, of which many people in the Viking era considered to be the 'official' entrance to Hell. ironically, the famed Viti craters of Krafla and Mývatn literally mean, "Hell", and Icelanders for many centuries believed that volcanoes were the physical entrance to such a place.

This most recent event is most likely a random anomaly, and probably not significant, however Iceland is a fascinating and random place as far as volcanoes are considered. Eyjafjallajökull erupted with little more than a month's notice after several centuries of inactivity, and other frequent offenders have laid dormant for decades. It is truly a landscape of unparalleled beauty and danger, and one of the few spots on the planet where you can be an eyewitness to how the earth builds land!

No comments:

Post a Comment

Comments are moderated. See the comment policy for details.