In a special report from 24 November the Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) stated that seismicity at Lewotobi Laki-laki began to increase over the previous few days. The dominant seismic signals, non-harmonic and low-frequency, indicated activity at shallow depths. Increased inflation was detected in tiltmeter data during the previous three days, although Global Navigation Satellite System (GNSS) data continued to show fluctuations in the vertical component over the past week. Beginning at 1400 on 24 November there was an increase in the number of deep volcanic earthquakes, indicating a rapid rise of magma. At 2100 the Alert Level was raised to 4 (the highest level on a scale of 1-4) and the public was warned to stay 6 km away from the center of Laki-laki and 7 km in an area clockwise from NW to NE

Geological Summary. The Lewotobi edifice in eastern Flores Island is composed of the two adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes (the "husband and wife"). Their summits are less than 2 km apart along a NW-SE line. The conical Laki-laki to the NW has been frequently active during the 19th and 20th centuries, while the taller and broader Perempuan has had observed eruptions in 1921 and 1935. Small lava domes have grown during the 20th century in both of the summit craters, which are open to the north. A prominent cone, Iliwokar, occurs on the E flank of Perampuan.

Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM)