Global Volcano Activity and the Gas Emissions They Emit
Currently, there are roughly 30 active volcanoes around the world. While this number seems small, experts note that having this many active sites is unusual rather than typical because volcanic regions span vast areas along tectonic plate boundaries, covering millions of kilometers.
Some volcanoes, such as the Yellowstone caldera in Wyoming, the La Garita volcanic system in Colorado, and Lake Toba in Sumatra, Indonesia, cover enormous districts. Yet one in particular stands out for its size and risk: Campos Flegrei near Naples in Italy. This supervolcano describes eruptions capable of expelling massive volumes of material in the past and sits near a population of several million people, making its potential impact especially significant.
In geology discussions, a supervolcano is defined as one that has expelled about 1,000 cubic kilometers of material at some point in its history. It may have a cluster of multiple crater mouths and remains a critical concern precisely because it lies adjacent to dense populations.
Another well-known example is Mount Vesuvius in Italy, famously destructive in antiquity and still regarded as one of the world’s most dangerous volcanoes. Nearby, Popocatépetl in Mexico has shown renewed activity, most recently erupting at the end of May this year. In the Asian region, Indonesia hosts several active volcanoes, including Karangetang and Dukono, among others that occasionally erupt. Southeast Asia together with the nations along the so‑called Ring of Fire continues to experience frequent volcanic events.
In the Philippines, multiple vents remain active in zones around the archipelago, highlighting ongoing volcanic activity across the region.
Joan Martí, a researcher with the Scientific Research Council and coordinator of a regional volcanology group, notes that Etna in Italy and Vesuvius in particular have long been considered among the most dangerous. Beyond Europe, observers continue tracking eruptions at Popocatépetl and other major Mexican volcanos to understand regional risk patterns.
There is also ongoing attention to the Indonesian volcanic arc, where several volcanoes erupt irregularly and contribute to the overall volcanic dynamics of the area. In the Philippines, a cluster of activity within the Ring of Fire shows that explosions occur with notable regularity across multiple sites.
Gas Emissions During Eruptions
During eruptions, volcanoes routinely release gases such as carbon dioxide and sulfur dioxide. These gases can rise to altitudes of twenty to thirty kilometers, influencing atmospheric conditions in ways that have been observed in historic eruptions. The gas plumes can alter climate and weather patterns and have recorded effects on nearby populations and environments, as seen in historic cases.
Carbon dioxide replaces oxygen in the air, which can affect breathing for people in close proximity. A recent example involves the Canary Island of La Palma, which entered a calm phase after a major eruption but later showed renewed activity and gas emissions that impacted adjacent towns. Efforts to monitor gas flows help protect communities that live near volcanic zones.
Sulfur emissions pose specific hazards because they can combine with water to form sulfuric acid, which may contaminate water supplies, pastures, and animal feed. These chemical interactions underscore the importance of monitoring gas emissions for public health and environmental safety.
Regueiro emphasizes that a volcano’s atmospheric impact can persist long after eruptions due to the large volumes of material suspended in the atmosphere. This effect should be considered alongside other volcanic consequences, such as meteotsunamis linked to submarine eruptions in the recent past. The South Pacific region has been a particular focus for such events.
Despite the strong influence of volcanic gases, researchers argue that the most lasting effects hinge on human emissions and longer-term climate interactions rather than isolated eruptions alone. The balance of natural and human contributions continues to shape regional air quality and environmental health.
In Spain, it is not anticipated that a major eruption will occur in the near term. After the La Palma event, communities on volcanic islands remain vigilant, with some areas showing continued, though limited, activity. For Stromboli, a small Italian island, even a modest eruption can complicate daily life due to the constant geologic activity around a coastal setting.