The eruption began on 20 March 2010, sometime between 10.30pm and 11.30pm, a few kilometres east of the Eyjafjallajökull glacier in the northern slopes of Fimmvörðuháls mountain pass. The first fissure was 500 metres long, pointing northeast–southwest, with 10–12 erupting lava craters which spewed around 1,000°C hot lava 150 metres in the air. Lava is alkaline so its movement to the west and east of the fissure is slow. It has flowed more than 4000 metres northeast of the fissures into Hrunagil canyon, forming a more than 200-meter long “lava”-fall, slowly approaching Þórsmörk. On 25 March scientists witnessed on location, for the first time in history, the formation of a pseudocrater during a steam explosion, while studying the eruption. And a new fissure opened around 7pm, about 200 meters northwest of the original fissure and lava coming from it has now started to flow into Hvannárgil canyon.