Q&A; on the eruption in Eyjafjallaj÷kull

How long will the eruption last?

The eruption continues. It is not possible to predict the duration of the eruption. Previous known eruptions from this volcano were in the years 1612, believed to have lasted only three days, and 1821-3, when it erupted on and off for over a year.

What kind of an eruption is it?

The eruption is an explosive eruption beneath a glacier. The ash is fluorine rich, of intermediate content and the particles are very fine.

Is the ash dangerous?

Yes, the fluorine is dangerous to livestock. The quantity is approximately 25-35 mg/kg according to chemical analysis carried out by the Institute of Earth Sciences, University of Iceland. The fine ash can also effect human health, for example the respiratory system.

Has ash fallen in Iceland?

Yes, in the southeast and extreme south of the country (downwind). Today ashfall is reported south of the volcano (19.04.). The wind has been quite strong so dry ash that fell earlier is blowing with the wind causing local reduction of visibility hazardous for driving.

How high is the ash plume?

The plume has not been detected on IMO's radar since early morning 18.04.2010. It may be under on average about 10000 feet (about 3 km). The greatest height that the plume has reached is 33000 ft (about 11 km) on the first eruption day.

How far has the ash plume reached?

The plume has been detected over the British Isles, east to Norway and Finland. The Icelandic Meteorological Office issues daily forecasts of ashfall.

In what direction does the wind blow?

Now (19.04.) the wind blows from the north over Iceland, carring the ash to the south. The northerly wind will decrease in strength until tomorrow, but remain from the north until Wednesday, when it will become more variable. Northerly winds are expected after that.

Why were there floods and can floods still be expected?

Several very sudden j÷kulhlaups (glacier outburst floods) have occurred during the subglacial eruption in Eyjafjallaj÷kull volcano. The largest one came in the very beginning of the event with maximum discharge about 2000-3000 m3/sec. Now the eruption is constrained to one vent and, therefore, very limited amount of ice is melted and, accordingly, little danger of large j÷kulhlaups. The floods are monitored by online gauges in several rivers around the volcanoes Katla and Eyjafjallaj÷kull. Large or damaging j÷kulhlaups are not expected in connection to this event unless changes occur in the eruption pattern.

How is the eruption monitored?

The Icelandic Meteorological Office monitors earth movements, water conditions and weather and issues warnings. Many kinds of measurements are carried out by the IMO and other agencies that provide valuable information used to warn of impending danger, for example potential eruptions and floods. The IMO's weather radar on the southwest tip of the country shows the height of the ash plume, which is important for calculating the distribution of the ash. There is a 24/7 watch at the IMO, where a meteorologist is present and a seismologist and hydrologist are on call. The IMO works closely with the National Emergency Agency, the University of Iceland and the British Meteorological Office, where the London VAAC (Volcanic Ash Advisory Centre) is stationed. The London office gives information on ash which are based on information from the Icelandic Met Office.

How are eruptions forecast and monitored in Iceland?

To forecast and monitor seismic and volcanic activity in Iceland, IMO operates a nationwide digital network of seismic stations and continuous GPS stations. Subglacial eruptions often coincide with j÷kulhlaups. To monitor the j÷kulhlaups IMO uses water-level gauges and electrical conductivity meters. More about this in an article in Eos.

How do I find basic weather information, present weather and forecasts?

Information on the weather conditions near the volcano can be viewed on the weather pages of the IMO-web and navigate from there. For the present weather one can view the newest synoptic analysis. The obseravations are plotted according to WMO standards. There are no highland stations near the volcano. The difference in the weather in the lowland and in the mountains can be considerable. Wind-chill and wetness (rain, snow or blowing snow) are always a potential hazard as sudden weather changes are more common on higher ground than in the lowland.


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