Two weeks ago, the Philippine Institute of Volcanology and Seismology recorded three distinct, short-lived explosions in less than five minutes at Taal Volcano. The eruption sent a column of ash and steam up to 1.2km into the air.

Despite this, it caused little disruption. The volcano remains at Alert Level 1, or “low-level unrest”, with a smaller eruption logged over the weekend.

Yet even small eruptions like these can reveal important clues about how volcanoes behave and why scientists closely monitor even relatively minor volcanic rumbling.

A history of big eruptions

Taal Volcano lies in Batangas Province, about 60km south of Manila. The active volcano sits on Volcano Island within Taal Lake. It is one of the Philippines’ 24 active volcanoes.

Taal is also among the country’s most closely monitored volcanoes and is one of only 16 Decade Volcanoes around the world. These are volcanoes with a history of large, destructive eruptions and significant risk to nearby populations. Others include Mount Etna in Italy and Mount Rainier in the United States.

Taal has a long history of much larger eruptions. In January 2020, it sent ash plumes more than 15km into the atmosphere, forcing the evacuation of hundreds of thousands of people,........

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