Active Volcanoes This Week

What the Weekly Volcanic Activity Report is

Every Thursday the Smithsonian Institution's Global Volcanism Program (GVP) and the US Geological Survey's Volcano Hazards Program publish the Weekly Volcanic Activity Report: a digest of volcanoes that showed notable activity during the report week (Thursday to Wednesday). Each entry condenses what national observatories, Volcanic Ash Advisory Centers (VAACs) and satellite monitoring reported over those seven days. Volcanoes fall into two groups. "New activity" means an eruption began, resumed after a pause, or changed character in a significant way — ash plumes suddenly rising much higher, pyroclastic flows appearing, an observatory raising its alert level. "Ongoing activity" covers eruptions that have been under way for a while and did not fundamentally change during the week: the same style of explosions, the same lava flows. On the map the first group is shown with red pulsing markers, the second with orange ones.

The summaries are full of alert levels and aviation colour codes. Every country runs its own scale — Alert Level 1–4 in Indonesia and the Philippines, 0–5 in Vanuatu, 1–5 in Japan — so they cannot be compared directly: "level 3" in one system may mean something quite different in another. The more universal one is the ICAO Aviation Colour Code that observatories share with air-traffic services: green means the volcano is quiet, yellow that unrest is above background, orange that an eruption is under way with little or no ash or that one is likely, and red that an eruption is producing a significant amount of ash. Plume heights are given above sea level (a.s.l.), in kilometres and feet, because that is how aviation uses them, and plume drift is given as a compass direction.

This is not a list of every erupting volcano on Earth. Around 40–50 volcanoes are erupting at any given moment, but the report only includes those for which new information arrived during the week and met the selection criteria: a notable change in activity, large ash emissions, evacuations, a change of alert level, or a volcano being added to monitoring. A volcano that has been quietly fountaining lava for years without incident can be absent from the list for weeks. The editors also stress that the notices are preliminary and subject to revision as events are studied in more detail; the carefully reviewed accounts are published later in the Bulletin of the Global Volcanism Network.

The source is the RSS feed of the Smithsonian / USGS Weekly Volcanic Activity Report. Summaries are shown in English exactly as published, without translation, so that the original wording is not distorted. Upstream, the report comes out once a week, on Thursdays by 23:00 UTC; we sync the feed every 6 hours, and the badge in the page header shows when the snapshot was last taken. Earlier weeks stay in the archive — pick one in the selector above the map to see how the picture has changed.