On the morning of 19 May 2026, Indonesia’s volcanology agency did something it does not do lightly: it raised Awu Volcano to Alert Level 3, the second-highest tier on the country’s four-level scale. The trigger was a swarm of 519 shallow volcanic earthquakes recorded beneath the mountain between 1 and 18 May, a pace of nearly 29 per day. A 4 km exclusion zone now rings the summit crater. But on Sangihe Island, where Awu dominates the skyline, tens of thousands of people live, farm, and go to school on slopes that previous eruptions have buried under superheated debris.
A volcano with a body count
Awu is a stratovolcano capped by a crater lake, rising on the northern end of Sangihe Island in North Sulawesi province, roughly 270 km northeast of Manado. It is one of Indonesia’s deadliest. The Smithsonian Institution’s Global Volcanism Program documents a string of catastrophic eruptions stretching back centuries. The combination of steep terrain, a crater lake that can interact explosively with rising magma, and dense settlement on the lower flanks makes any escalation at Awu a serious concern. This is not a remote peak. Roads, a port, health clinics, and schools all sit within the zones that historical eruptions have reached.
What the earthquake swarm tells scientists
The core data comes from Indonesia’s Center for Volcanology and Geological Hazard Mitigation, known as PVMBG, and has been independently cross-referenced by the Smithsonian’s Global Volcanism Program. Between 1 and 18 May, instruments logged 519 shallow volcanic earthquakes and 24 deep volcanic earthquakes beneath Awu. The alert was formally raised at 13:00 local time on 19 May.
Shallow volcanic earthquakes matter because they indicate magma or superheated fluids moving at relatively low depths, closer to the surface. A swarm this dense over eighteen days signals that something is changing inside the volcano’s plumbing system. The critical question is trajectory: an accelerating swarm with progressively shallower events would suggest magma is actively rising, while a stable or declining pattern could mean the system is venting pressure without building toward eruption.
That trajectory is not yet clear from publicly available data. PVMBG has confirmed the aggregate count for the eighteen-day window, but daily breakdowns and depth distributions have not been published in a format accessible to international observers. Ground deformation measurements, which would show whether the volcanic edifice is physically swelling, have not appeared in public-facing reports either. Satellite-based radar can detect centimeter-scale inflation of a volcano’s surface, and such readings would be a strong indicator of magma intrusion. PVMBG almost certainly monitors deformation internally, but those results remain behind closed doors for now.
Similarly, there is no accessible summary of gas emission trends. Rising sulfur dioxide flux often accompanies magma approaching the surface, and changes in fumarolic activity or crater lake color can signal shifting conditions underground. Domestic bulletins have mentioned visual observations in passing, but without systematic, translated logs, outside analysts cannot piece together the full picture.
Tens of thousands in the hazard footprint
A peer-reviewed vulnerability analysis published in the Spasial journal at Sam Ratulangi University mapped how many residents live inside Awu’s hazard zones. The researchers combined settlement maps, historical eruption footprints, and administrative records to estimate exposure to pyroclastic flows, lahars, and ashfall. Their findings, available through the journal’s online archive and via its digital object identifier, support the characterization that tens of thousands of people reside inside zones that would be directly affected by a significant eruption.
The exposure is not uniform. Some villages sit in valleys that have repeatedly funneled lahars downslope. Others occupy ridges more vulnerable to heavy ashfall but less to dense pyroclastic surges. Critical infrastructure, including the roads and port facilities that any evacuation would depend on, also falls within mapped hazard zones. A large eruption would not just threaten lives directly; it could cut off the routes needed to move people out and supplies in.
The study predates the current unrest, and population growth or new construction since publication could shift the actual numbers. But as a baseline, it establishes the scale of what is at stake: this is not a volcano surrounded by empty jungle.
The gap between the exclusion zone and the real danger
The 4 km exclusion zone is a regulatory boundary, not a physical barrier. It restricts entry and activity near the summit, but homes, farms, and roads extend well beyond that perimeter into areas that past eruptions have devastated. Many households depend on agriculture on Awu’s fertile slopes, and suspending daily life is not a simple ask when livelihoods are tied to the land.
This tension is not unique to Awu. Across Indonesia, millions of people live on or near active volcanoes because volcanic soil supports productive farming and alternative land is scarce. At Awu, no direct evacuation orders from local regency officials or Indonesia’s national disaster agency, BNPB, have appeared in verified reporting as of late May 2026. Alert Level 3 typically triggers enhanced monitoring, preparedness measures, and recommendations to avoid high-risk zones. Mandatory mass evacuation usually accompanies Level 4. Whether authorities have begun quietly relocating residents from the most exposed settlements, pre-positioning relief supplies, or clearing evacuation routes has not been confirmed publicly.
What a Level 4 alert would mean for Sangihe Island
Level 4, the highest tier on Indonesia’s volcanic alert scale, signals that an eruption is imminent or underway. It would almost certainly trigger mandatory evacuations, military and police involvement in moving people, and activation of national disaster response protocols. For an island community like Sangihe, that raises logistical challenges that mainland volcanoes do not face. Evacuation by sea requires functioning ports and enough vessels. Evacuation by air depends on ash conditions and limited airstrip capacity. If Awu were to produce a large eruption column, regional air traffic could also be disrupted.
None of this is inevitable. Many volcanic swarms subside without eruption. But the confirmed data, 519 shallow earthquakes in eighteen days beneath a volcano that has killed thousands in documented eruptions, places Awu in a category that demands close attention. PVMBG’s decision to raise the alert level reflects a professional judgment that the risk has crossed a threshold worth acting on.
For the communities on Awu’s slopes, the weeks ahead hinge on information that has not yet been made public: whether the swarm is accelerating or fading, whether the ground is inflating, whether gas emissions are climbing. Until PVMBG or BNPB releases more granular monitoring data, the most defensible position is the one the agency has already taken. The mountain is in a heightened state of unrest, the potential for dangerous activity is real, and tens of thousands of people remain within reach of whatever Awu does next.
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*This article was researched with the help of AI, with human editors creating the final content.
