PVMBG raises Lewotobi Laki-laki to Level III after seismicity and inflation increase, Indonesia
Indonesia’s Center for Volcanology and Geological Hazard Mitigation (PVMBG) raised the alert level for Lewotobi Laki-laki in East Flores, East Nusa Tenggara, from Level II to Level III at 13:00 WITA (05:00 UTC) on May 12, 2026. The decision followed increased deep volcanic earthquakes, persistent non-harmonic tremor, inflation, and surface activity from May 1 to 11. Residents and tourists were told to avoid activity within a 5 km (3.1 miles) radius of the eruption center.
Lewotobi Laki-laki on May 9, 2026. Credit: PVMBG
Indonesia’s Geological Agency, through PVMBG, raised Lewotobi Laki-laki to Level III / Siaga after visual and instrumental monitoring showed increased volcanic activity beneath the volcano in Flores Timur Regency. This placed Lewotobi Laki-laki among three Indonesian volcanoes at Level III.
Lana Saria, Acting Head of Indonesia’s Geological Agency (Badan Geologi), said that monitoring from May 1 to 11 was dominated by deep volcanic earthquakes. 21 to 32 deep volcanic earthquakes were recorded per day from May 1 to 4, while non-harmonic tremor remained high and persistent at 17 to 27 events per day.
Deep volcanic earthquakes point to a strong supply of magma or magmatic fluids into the volcanic system, while non-harmonic tremor shows continued movement of shallow volcanic fluids.
Deep earthquakes later decreased to 8 to 12 events per day, approaching May 10, but remained above previous normal conditions, while non-harmonic tremor reached 27 events on May 9.
Surface activity was recorded through rockfalls and exhalations on several observation days, especially on May 2 and 3 and May 6, while inflation measurements showed continued pressure accumulation inside the volcano’s magmatic system.
MAGMA Indonesia reported white smoke from the main crater was observed at moderate intensity on May 12, up to 200 m (650 feet) from the summit.
Updated hazard-zone map divides the Lewotobi Laki-laki hazard area into three zones.
KRB III covers a 4 km (2.5 miles) radius from the summit and is exposed to directed eruptions with lateral ballistic ejecta, especially from the northwest to northeast sectors, as well as pyroclastic flows, volcanic material avalanches, lava flows, heavy ashfall, and large volcanic gravel.
KRB II extends from 4 to 6 km (2.5 to 3.7 miles) and is exposed to possible expansion of pyroclastic flows, lava flows, ballistic ejecta, and lahars if eruptive intensity increases. KRB I extends from 6 to 9 km (3.7 to 5.6 miles) and is exposed to lahars, volcanic ashfall, and lapilli up to about 10 mm (0.4 inches) in diameter during larger eruptive activity.
PVMBG recommended that residents, visitors, and tourists avoid all activity within a 5 km (3.1 miles) radius of the eruption center. Communities along rivers that drain from the summit are urged to watch for rain-triggered lahars during high-intensity rainfall, especially in Dulipali, Padang Pasir, Nobo, Nurabelen, Klatanlo, Hokeng Jaya, Boru, and Nawakote. Residents affected by ashfall are advised to use masks or nose-and-mouth coverings to reduce respiratory exposure.
The Lewotobi volcanic edifice is located on eastern Flores Island and consists of adjacent Lewotobi Laki-laki and Lewotobi Perempuan stratovolcanoes, with summits less than 2 km (1.2 miles) apart.
References:
1 Kenaikan Tingkat Aktivitas G. Lewotobi Laki-laki, NTT dari Level II (Waspada) menjadi Level III (Siaga) Tanggal 12 Mei 2026 Pukul 13.00 WITA – PVMBG – May 12, 2026
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