According to Frederick Belton’s Ol Doinyo Lengai website, a local camp manager reported to a visitor, that several large explosive eruptions accompanied by “bangs” on 1 February. The manager noted that ash plumes were originating from a location in the crater that was further N than previous locations. The visitor saw ash plumes on 3 February that rose to altitudes of 3.2-3.3 km (10,500-10,800 ft) a.s.l. The next day, an ash plume rose to an altitude of 4.3 km (14,100 ft) a.s.l. Eruptions also occurred on 6 February.
Source: Frederick Belton’s Ol Doinyo Lengai website – “Report provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”