At the mouth of the crater, the gases, ejecta, and volcanic plume have created a rare weather phenomenon known as volcanic lightning (or a "dirty thunderstorm").
When rocks and other ejecta collide with one another, they create static electricity.
This, with the abundant water-ice at the summit, aids in making lightning.

High-fluoride Hekla eruptions pose a threat to foraging livestock, especially sheep.
Fluoride poisoning can start in sheep at a diet with fluorine content of 25 ppm.
At 250 ppm, death can occur within a few days.
In 1783, 79% of the Icelandic sheep stock were killed, probably as a result of fluorosis caused by the eruption of Laki.
The effect also spread beyond Iceland.
Ash from the current Eyjafjallajökull eruption contains one-third the concentration typical in Hekla eruptions, with a mean value of 104 mg of fluoride per kg of ash.
Large-scale release of sulphur dioxide into the troposphere also poses a potential health risk, especially to people with pre-existing breathing disorders.

As of 15 April, the eruption was not large enough to have an effect on global temperatures like that of Mount Pinatubo and other major past volcanic eruptions.
One previous related sequence of eruptions of this volcano, beginning in 1821 is recorded as having lasted for over two years, but no single set of major eruptions is known to have lasted more than 'several days'.
At the mouth of the crater, the gases, ejecta, and volcanic plume have created a rare weather phenomenon known as volcanic lightning (or a "dirty thunderstorm"). When rocks and other ejecta collide with one another, they create static electricity. This, with the abundant water-ice at the summit, aids in making lightning.
High-fluoride Hekla eruptions pose a threat to foraging livestock, especially sheep. Fluoride poisoning can start in sheep at a diet with fluorine content of 25 ppm. At 250 ppm, death can occur within a few days. In 1783, 79% of the Icelandic sheep stock were killed, probably as a result of fluorosis caused by the eruption of Laki. The effect also spread beyond Iceland. Ash from the current Eyjafjallajökull eruption contains one-third the concentration typical in Hekla eruptions, with a mean value of 104 mg of fluoride per kg of ash. Large-scale release of sulphur dioxide into the troposphere also poses a potential health risk, especially to people with pre-existing breathing disorders.
As of 15 April, the eruption was not large enough to have an effect on global temperatures like that of Mount Pinatubo and other major past volcanic eruptions. One previous related sequence of eruptions of this volcano, beginning in 1821 is recorded as having lasted for over two years, but no single set of major eruptions is known to have lasted more than 'several days'.
2010 eruptions of Eyjafjallajökull