The eruption continued until 7 February 1784, but most of the lava was ejected in the first five months. One study states that the event occurred as ten pulses of activity, each starting with a short-lived explosive phase followed by a long-lived period of fire-fountaining. Grímsvötn volcano, from which the Laki fissure extends, was also erupting at the time, from 1783 until 1785. The outpouring of gases, including an estimated 8 million tons of hydrogen fluoride and an estimated 120 million tons of sulfur dioxide, gave rise to what has since become known as the Laki haze across Europe.