Ash dispersal forecast and civil aviation workshop : Geneva, Switzerland, 18-20 October 2010 : Hekla 2000 benchmark document

Hekla began erupting at 18:19 (LT=UTC) on February 26th 2000. Precursory earthquake activity was noted at 17:00, with small earthquakes detected by a seismograph close to the summit of the volcano followed by larger earthquakes at 17:29. Continuous low-frequency tremor began at the same time when the eruption cloud was first observed, indicating the start of the explosive phase of the eruption at 18:19 (2. Summary of the eruption chronology http://www.earthice.hi.is/page/hekla26feb2000). A more than 10 km high eruption column formed in the first few minutes of the eruption reaching a maximum of 12.5km, detected by radar in Keflavík and observed by aircraft and from the ground (Höskuldsson et al. 2007). Weather conditions were poor and the eruption started in darkness so that direct visual observations of the early part of the eruption are limited (Höskuldsson et al. 2007). Radar observations are discussed at Lacasse et al. (2004) and satellite observations at Rose et al. (2003). The explosive part of the eruption lasted only a short time, around 60 minutes, reaching a peak after only 40 minutes after which time a fissure of 6.6km length began to open (Höskuldsson et al. 2007).