Locations of active volcanoes around the world. Data is provided by the United States Geological Survey’s (USGS) Natural Hazards Support System (NHSS) and is updated on a regular basis. Graphic by RAYMOND GRUMNEY Notes about the data U.S. Volcanoes: Information about active volcanoes in the United States is derived from the Recent Volcano Observatory Activity Reports generated by the USGS Volcano Hazards Program. NHSS retrieves this information every 12 hours and uses it to refresh the features in the U.S. Volcanoes layer. World Volcanoes: NHSS derives this information from the Weekly Volcanic Activity Report generated as a cooperative project between the Smithsonian's Global Volcanism Program and the USGS Volcano Hazards Program. NHSS updates this layer once a week. Notices of volcanic activity posted in the Weekly Volcanic Activity Report are preliminary and subject to change as events are studied in more detail.