A large explosive eruption began on the 4 September 2007, producing a 3 kilometres (1.9 mi) high eruption column and a new, 100 metres (330 ft) deep and 300 metres (980 ft) wide crater. The explosive activity continued into 2008, when the volcano settled back into the effusion of lava flows; a cinder cone formed in the northern crater during the eruption. Aerosol clouds from the eruption extended over east Africa. The 2007 eruptions forced the evacuation of three villages and disturbed air travel in the touristically important area; livestock fatalities and injuries to people led to requests that the government of Tanzania enact access restrictions to the volcano and to increased awareness of the threat formed by the volcano. Wild animals such as flamingos were also impacted by the eruption. The eruption was preceded in July by seismic activity, which was frequently mistaken for renewed eruptions, and the intrusion of a dyke less than 20 kilometres (12 mi) from Ol Doinyo Lengai.