The following was received by the Smithsonian's Global Volcanism Network. This report is preliminary and subject to change as the event is studied in more detail. We will forward additional significant information as it becomes available.
Wednesday, 2nd October 1996, 16:00
The Skeidararsandur area will be closed to night 20-11 because of possible flooding. Activity started in Bardarbunga in Sunday then moved to the area N of Grimsvotn caldera where an eruption started on Monday. To day activity has moved back to Bardarbunga central and large earthquakes up to M4, have occurred in the afternoon.
Bardarbunga and Grimsvotn are two central volcanoes under Vatnajokull, Grimsvotn has been the more active one (last 1983), but eruptions have also happened in Bardarbunga in historical times. Now it seems that activity is in both these centrals which is unusual, there is even thought that an eruption might be already started in Bardarbunga. As there is a dense cloud cover over the eruption sites it is not known what is realy happening. The eruption continues N of Grimsvotn caldera. If an eruption starts in Bardarbunga the meltwater will more likely go towards north.
Thursday, 3rd October 1996, 09:10
Eruption continues and the vapour/ash column now extends to 30.000 feet or 10 km altitude and has been seen from aircraft on international routes. It is seen from Hofn village in SE Iceland being white in colour and as it seems little ash. It is now one ash column, tilting to N. Little ashfall is reported from N Iceland. Observations in late afternoon yesterday indicated that the eruption had moved to a new collapse in the glacier 1-1.5 km from where it started. The fissure is believed to be 6-8 km long. The direction seems to be north, but this is not clear yet.
It seems that water flows to south under the glacier, no indications are of meltwater in rivers to the north.
Activity started in Bardarbunga in Sunday then moved to the area N of Grimsvotn caldera where an eruption started on Monday. Wedensday afternoon the activity has moved back to Bardarbunga central and large earthquakes up to M4, have occurred in the afternoon. Seismic activity was less last night and the volcanic tremour less then yesterday regarded due to easier passage for the magma to the surface. It is hoped that eartquakes in Bardarbunga proper do not indicate beginning of an eruption more to the west. At the moment the eruption site is between Bardarbunga and Grimsvotn and hopefully it stays there. Apart from flooding/surging to the south to the Skeidararsandur outwash plain no constructions are in danger and no inhabited places. It is therefor an ideal situation for an eruption, though we geologist would have liked it to be more accessible.
Jokulhlaup (surge) from Grimsvotn caldera has not started, it is feared it migth be quite large. At the moment the road management is enforcing flood-levees and preparing to cut through the roads to make easyer passages for the water, thus saving the bridges in the flood plain.
Yesterday was cloudy with heavy rain. It cleared up in late afternoon. Daylight is now 08-18. Today is clear weather and good view should be of the eruption from the air. As the glacier has fractured a lot around the eruption site all traffic is banned in the western half of Vatnajokull glacier.
Helgi Torfason
National Energy Authority
Grensasvegur 9 108 Reykjavik