The Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) reported that eruptive activity continued at Lewotobi Laki-laki during 12-18 February. A sudden increase in the number of volcanic earthquakes was detected at 2200 on 11 February and the seismicity remained at high levels. At 0300 on 12 February the exclusion zone was expanded to a radius of 5 km from the center of Laki-laki and 6 km in a semicircle counterclockwise from the NE to the SW. The Alert Level was raised to 4 (on a scale of 1-4) at 0300 on 13 February and the exclusion zone was again expanded to 6 km from the center of Laki-laki and 7 km in a semicircle counterclockwise from the NE to the SW. PVMBG noted that during 3 January-13 February the seismic network also detected increases in harmonic tremor, low-frequency earthquakes, and shallow volcanic earthquakes. Observable activity also increased and fumarolic plumes rose from cracks on the upper NW flank, though weather conditions often obscured views. Crater incandescence was visible, but often faint. BNPB recommended that residents evacuate from the six villages within the expanded exclusion zone including Nobo (5 km NE), Dulipali (6 km NNW), and Hokeng Jaya (3 km WNW).

During 13-17 February dense white plumes rose 400-600 m above the summit. Seismicity fluctuated, but notably deep volcanic earthquakes were recorded during 16-17 February while shallow volcanic earthquakes were not. At 0558, 1622, and 2343 on 17 February dense gray ash plumes rose 400-900 m above the summit and drifted N and 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.

Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG, also known as CVGHM), Badan Nacional Penanggulangan Bencana (BNPB)