Febraury 26

Photographs taken by Gísli Óskarsson (e-mail: gosk@ismennt.is)
Courtesy of Gísli and Icelandic National Broadcasting Service (e-mail: tvnews@ruv.is)

Hekla volcano in South Iceland began a new eruption on February 26, 2000 at 18:19 GMT.

A short-term precursory earthquake activity was recorded by the seismic networks of the Science Institute, University of Iceland, and the Iceland Meteorological Office. Small earthquakes were detected by a seismograph near the summit of Hekla beginning at 17:00.  This activity gradually increased and the first locatable earthquakes occurred at 17:29. Continuous low-frequency tremor characteristic of Hekla eruptions began at 18:19, and at the same time the eruptive cloud was spotted by observers.

A network of borehole strainmeters operated by the Iceland Meteorological Office also detected precursory strain change associated with magma movements. A warning was issued to the National Civil Defense of Iceland about one hour before the eruption, and the public was alerted about the imminent eruption about 15 minutes before it began, through news on the Iceland national radio.

Initially, a 6-7 km long eruptive fissure opened up along most of the Hekla ridge. A discontinuous curtain of fire emanated from the whole fissure. More than 10 km high ash plume formed within few minutes of the beginning of the eruption, and was carried with light winds towards north. Judged from the amplitude of the eruption tremor on the nearby seismographs the eruption reached peak intensity in the first hour of activity, but then the activity gradually declined.

The maximum thickness of the ash sector, 21 km north of the volcano, was 4-5 cm when measured 7 hours after the onset of the eruption. Most of the ash fell in uninhabited areas in the interior of Iceland, but asmall amount of ash fell in inhabited areas in North Iceland. Ash fall was reported on the Grimsey island off the north cost of Iceland, at a distance of 300 km from Hekla.