Nobody knows how many active volcanoes there are on the Earth. For one thing, activity does not necessarily mean that a volcano is spurting lava right now. Signs of life in recent decades that might be resumed in the future are enough for a volcano to be viewed as active. In August 2005, some thorough people at Michigan Technological University in the US had a stab at cataloguing the Earth's active volcanoes (see www.geo.mtu.edu/volcanoes/world.html).
- One In the Antarctic. Mount Erebus
- Two In mainland Europe, Stromboli and Etna, both in Italy
- Six In Iceland
- One In mainland South America, plus one on the Galapagos Islands in the Pacific
- One In the West Indies, on Montserrat
- Sixteen In Central America, including Popacatapetl in Mexico, five in Guatemala, two in Costa Rica, seven in El Salvador and one in Nicaragua
- Three in the continental US, including Mount St Helens
- Five in and around Alaska
- Three In Hawaii and two others In the Pacific
- Two In New Zealand
- One In Japan, Mount Unzen
- Four in Kamchatka, Russia
- Ten In the Indian Ocean, Indonesia and the Philippines, including Mount Pinatubo, the site of spectacular volcanism in the 1990s
- One In Africa, on the Cape Verde Islands
All of these are active or have been recently. To them must be added the large number of ocean ridges where more or less continuous volcanism is in progress.
Every Wednesday, the US Geological Survey and the Smithsonian Institution issue their weekly alert on volcanic activity. It excludes long-running activity and sea-floor volcanism, focusing on new and potentially hazardous volcanism. See www.volcano.si.edu/reports/usgs.
For more general information see:
Cascades Volcano Observatory vulcan.wr.usgs.gov/home/html
USGS Volcano Hazards Program volcanoes.usgs.gov