Report on Hekla (Iceland) — 27 March-2 April 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 27 March-2 April 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Hekla (Iceland). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 27 March-2 April 2013. Smithsonian Institution and US Geological Survey.
63.983°N, 19.666°W; summit elev. 1490 m
All times are local (unless otherwise noted)
On 29 March the Icelandic Meteorological Office noted that Hekla had been quiet the previous few days; no additional earthquakes had been detected since a period of increased seismicity during 10-26 March. The Icelandic Civil Defense continued to maintain a level of "uncertainty".
Geologic Background. One of Iceland's most prominent and active volcanoes, Hekla lies near the southern end of the eastern rift zone. Hekla occupies a rift-transform junction, and has produced basaltic andesites, in contrast to the tholeiitic basalts typical of Icelandic rift zone volcanoes. Vatnafjöll, a 40-km-long, 9-km-wide group of basaltic fissures and crater rows immediately SE of Hekla forms a part of the Hekla-Vatnafjöll volcanic system. A 5.5-km-long fissure, Heklugjá, cuts across the 1491-m-high Hekla volcano and is often active along its full length during major eruptions. Repeated eruptions along this rift, which is oblique to most rifting structures in the eastern volcanic zone, are responsible for Hekla's elongated ENE-WSW profile. Frequent large silicic explosive eruptions during historical time have deposited tephra throughout Iceland, providing valuable time markers used to date eruptions from other Icelandic volcanoes. Hekla tephras are generally rich in fluorine and are consequently very hazardous to grazing animals. Extensive lava flows from historical eruptions, which date back to 1104 CE, cover much of the volcano's flanks.