A volcano responsible for killing more than 7,000 people across three major eruptions is shaking again, and Indonesian authorities have raised its alert to the second-highest level on the national scale.
Awu, a 1,320-meter stratovolcano on Sangihe Besar island in North Sulawesi province, was elevated to Level III (“standby”) by Indonesia’s Center for Volcanology and Geological Hazard Mitigation (PVMBG) after weeks of escalating seismic activity that began no later than March 2026 and continued through at least late April. Only Level IV, “warning,” sits above the current designation, and it typically triggers mandatory evacuations.
The Sangihe Islands regency is home to roughly 130,000 people. Awu’s summit, which holds a crater lake capable of generating fast-moving lahars, rises just 5 kilometers from the regency capital of Tahuna. Coastal towns, fishing villages, and farmland ring the volcano’s lower slopes, and the island’s limited road network funnels toward a single port and a small airstrip, both of which could be cut off quickly by ashfall or pyroclastic debris.
A history written in disaster
Awu’s record, cataloged by the Smithsonian Institution’s Global Volcanism Program (GVP), makes clear why even moderate unrest here commands attention. In 1711, an eruption killed approximately 3,000 people across the island. In 1856, another explosive event claimed around 2,806 lives. A third major eruption in 1892 killed roughly 1,532. Smaller but still dangerous eruptions followed in 1913, 1921, 1922, and 1966, the last of which produced pyroclastic flows and lahars that reached populated areas.
Several of these disasters involved the crater lake. When magma heats or displaces a large body of water sitting inside a summit crater, the result can be sudden steam explosions or lahars, fast-moving slurries of water, rock, and volcanic debris that travel down river valleys at speeds communities cannot outrun on foot. Awu’s crater lake remains intact today, adding a layer of hazard that purely “dry” volcanoes do not pose.
What monitoring data shows
Two reports from the GVP document the current unrest in detail. A 22 March 2026 volcanic activity report recorded rising seismicity and tremor anomalies that had been building over preceding weeks. A follow-up 29 April 2026 summary extended the chronology through late April, tracing its data back to PVMBG’s real-time MAGMA Indonesia monitoring platform.
The key takeaway from both reports: the seismic unrest was not a brief spike. Tremor activity persisted and, by some measures, intensified across more than five weeks of documented observation. That sustained pattern is what prompted PVMBG to move Awu from Level II (“advisory”) to Level III (“standby”), a designation that widens exclusion zones around the crater and puts disaster-response agencies on higher readiness.
PVMBG’s alert thresholds factor in earthquake frequency, tremor amplitude, ground deformation, gas emissions, and visual observations. The specific values that triggered the standby designation have not been published in the GVP summaries, so outside observers can track the direction of change but cannot calculate precise eruption probabilities from public data alone.
What is still unknown
Precise daily earthquake counts and Real-time Seismic Amplitude Measurement (RSAM) readings after 29 April 2026 have not yet appeared in publicly available GVP reporting. Without that granular data, it is difficult to judge whether tremor rates are still climbing, leveling off, or beginning to decline. Volcanologists watch closely for patterns such as accelerating seismic swarms or abrupt quiet periods, both of which can precede explosive events.
No formal evacuation orders from Indonesia’s National Disaster Management Authority (BNPB) or North Sulawesi provincial officials have surfaced in the institutional reporting reviewed as of late May 2026. Local authorities may have expanded exclusion zones around the crater, but the specific radius and the number of people relocated, if any, are not confirmed in available records.
The type of eruption Awu might produce also remains an open question. Its history includes explosive eruptions that sent pyroclastic flows racing down its flanks and events that generated lahars from the crater lake. Whether the current unrest points toward a phreatic steam explosion, a magmatic eruption, or a gradual return to quiet cannot be determined from seismic summaries alone. Geochemical sampling of the crater lake, sulfur dioxide flux measurements, and satellite-based deformation studies would help narrow the possibilities, but those datasets have not appeared in the public record.
Why Sangihe’s geography raises the stakes
Sangihe Besar is a remote volcanic island roughly 270 kilometers north of Manado, the provincial capital of North Sulawesi. It sits in the Sangihe arc, a chain of volcanic islands stretching between Sulawesi and Mindanao in the Philippines. Reaching the island requires either a flight to Naha airport or a ferry crossing that can take several hours depending on sea conditions.
That isolation cuts both ways. In normal times, it means Awu’s activity draws less outside attention than volcanoes on Java or Bali. During a crisis, it means evacuation capacity is constrained by the number of available vessels, the condition of a single main road network, and weather that can ground small aircraft. Ashfall on the runway or heavy seas could effectively strand communities on the island during the window when leaving matters most.
Regional air traffic is also a concern. Volcanic ash clouds can damage jet engines and abrade cockpit windshields, prompting aviation authorities to reroute or ground flights across wide corridors. If Awu produces a significant ash column, flight paths between Manado, Davao, and other regional hubs could be affected.
What residents and travelers should watch
PVMBG’s MAGMA Indonesia platform publishes daily volcanic updates and is the most direct public source for changes in Awu’s alert status or exclusion-zone boundaries. Anyone with family, property, or travel plans connected to the Sangihe Islands should monitor that platform and follow directives from local civil-protection authorities.
Travelers in North Sulawesi should check airline advisories and consider flexible booking arrangements while the standby alert holds. Residents near the volcano should know their nearest evacuation route and have a go-bag prepared. Communities downstream of river valleys that originate near the summit face the highest lahar risk and should treat any unusual rumbling, changes in river water color, or official sirens as immediate signals to move to higher ground.
Many volcanoes experience extended periods of elevated unrest without producing large eruptions, and a standby alert does not mean an eruption is imminent. But Awu’s record leaves little room for complacency. This is a volcano that has killed thousands before, that holds a crater lake capable of amplifying any eruption’s destructive reach, and that sits on an island where escape options are limited. Staying informed through official channels and respecting exclusion zones remain the clearest steps for anyone in range as the weeks ahead unfold.
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*This article was researched with the help of AI, with human editors creating the final content.
