Indonesia has over 100 active volcanoes, including Mount Lewotobi Laki-laki, which is currently highly active. As of May 18, 2025, officials from the Center for Volcanology and Geological Disaster Mitigation (PVMBG) have raised the alert level from 3 (alert) to level 4 (warning) — the highest alert level — as it erupted the night before. 

Though the eruption was small, experts are still monitoring the situation as the level 4 warning stays in effect. Learn more about what these levels indicate, along with the methods volcanologists use to monitor and alert people about volcanoes in Indonesia and around the world.

Mount Lewotobi Laki-laki Eruption

According to a translated press release from the PVMBG, “the eruption produced an eruption column reaching 3,000 [about 9,800 feet] to 5,500 [about 18,000 feet] meters above the peak of the mountain or around 7,000 [about 23,000 feet] meters above sea level.”

The eruption was accompanied by thick, gray ash that moved towards the west and northwest. According to the Multiplatform Application for Geohazard Mitigation and Assessment in Indonesia (MAGMA Indonesia) — part of PVMBG — the eruption registered at 44 millimeters on a seismograph and lasted for about 43 seconds. 

Though the eruption was smaller and not explosive, officials warn that residents and tourists should not go within a 3.5-mile radius of the volcano. Residents have not been evacuated from the area, but officials have also noted to wear masks to prevent inhaling volcanic ash and monitor for heavy rains that could increase the possibility of lava flows. 

Initially, the PVMBG rated the activity level for Mount Lewotobi Laki-laki at a 3, but since the increase in activity, it was raised to a 4, the highest activity level.  

Read More: 5 of the Most Explosive Volcanic Eruptions

Volcanic Activity Levels in Indonesia

With the frequency of eruptions in Indonesia, MAGMA Indonesia monitors and informs the area about volcanic activity. They’ve broken down volcanic activity levels, like the one at Mount Lewotobi Laki-laki, into four levels. 

• Level 1 has a normal status. Area residents can still go about their daily lives, but around the volcano, there may be signs of toxic gases, though this doesn’t happen at every volcano.

• Level 2 has an alert status. There may be increased activity, but with this level, the public can still carry on with their daily activities. The public should stay vigilant in case anything changes and an eruption occurs. 

• Level 3 also has an alert status. The volcano may be erupting and there is obvious change in activity. The public should avoid the area surrounding the volcano, and if in close proximity, begin to prepare for evacuation.

• Level 4 is the highest on the scale. It has the same description as level 3, except that eruption is imminent. The surrounding residents should evacuate as soon as and as safely as possible.

Global Volcanic Observation 

Countries across the globe have their own monitoring and alert systems that work to keep people safe from volcanic activity. In the U.S. the United States Geological Survey (USGS) uses a similar 4-level system that ranges from normal to advisory to watch to warning. Mexico also uses a 4-level system, while New Zealand uses a system that rates activity from 0 to 5.

Though some of the volcano activity and alert systems can be on a different scale, most countries seem to follow the same volcanic aviation scale, known as the Volcano Observatory Notice for Aviation (VONA). This color-coded system keeps air traffic safe. The colors are green, yellow, orange, and red, and indicate whether or not airplanes should fly in the area.

Read More: The Axial Seamount Volcano Could Still Erupt in 2025, and Benefit Marine Life

Article Sources

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A graduate of UW-Whitewater, Monica Cull wrote for several organizations, including one that focused on bees and the natural world, before coming to Discover Magazine. Her current work also appears on her travel blog and Common State Magazine. Her love of science came from watching PBS shows as a kid with her mom and spending too much time binging Doctor Who.