This map layer includes Holocene volcanoes, which are those thought to be active in the last 10,000 years, which are within an extended area of the northern hemisphere centered on the United States. The data are a subset of data available from the Global Volcanism Program, Smithsonian Institution at http://www.volcano.si.edu/world/summary.cfm. This file is a replacement for the April 2004 map layer. These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. Further information on the Global Volcanism Program of the Smithsonian Institution is available at http://www.volcano.si.edu/The International Association for Volcanology and Chemistry of Earth's Interior (IAVCEI), The World Organization of Volcano Observatories (WOVO), and the Global Volcano Model (GVM) have sanctioned the Global Volcanism Program (GVP) to assign official names and numbers to the world's volcanoes. The purpose of the numbers is to prevent ambiguity regarding the name and location of volcanoes that may have non-unique names, or that are known by multiple names.The original VNums were based on a system developed in the 1950's for the IAVCEI Catalog of Active Volcanoes of the World (CAVW). GVP policy had been to embed significant geographical, historical, and age information in the numbers. As a result GVP often changed VNums, most frequently to accommodate newly recognized volcanoes in a particular geographical region, which over time undermined the goal of preventing ambiguity.After moving VOTW to a new database platform, we developed a new VNum system. During this process GVP staff took into account the needs of the International Civil Aviation Organization (ICAO) and other stakeholders to have numbers compatible with modern computing systems. Holocene, Pleistocene, and Tertiary volcanoes all fall under the new unified numbering system, allowing interoperability between VOTW and new databases under development globally (e.g. WOVOdat, LaMEVE). Letters and characters (hyphens and equals signs) have been eliminated. Secondary numbers have been added for subfeatures associated with each volcano. None of the new numbers start with 0 or 1 to avoid confusion with the legacy system. While a connection remains to the older system, the geographic link to CAVW regions and subregions is no longer mandatory.We feel that this change is in the best long-term interest of the community.

This map layer includes Holocene volcanoes, which are those thought to be active in the last 10,000 years, which are within an extended area of the northern hemisphere centered on the United States. The data are a subset of data available from the Global Volcanism Program, Smithsonian Institution at http://www.volcano.si.edu/world/summary.cfm. This file is a replacement for the April 2004 map layer. These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. Further information on the Global Volcanism Program of the Smithsonian Institution is available at http://www.volcano.si.edu/The International Association for Volcanology and Chemistry of Earth's Interior (IAVCEI), The World Organization of Volcano Observatories (WOVO), and the Global Volcano Model (GVM) have sanctioned the Global Volcanism Program (GVP) to assign official names and numbers to the world's volcanoes. The purpose of the numbers is to prevent ambiguity regarding the name and location of volcanoes that may have non-unique names, or that are known by multiple names.The original VNums were based on a system developed in the 1950's for the IAVCEI Catalog of Active Volcanoes of the World (CAVW). GVP policy had been to embed significant geographical, historical, and age information in the numbers. As a result GVP often changed VNums, most frequently to accommodate newly recognized volcanoes in a particular geographical region, which over time undermined the goal of preventing ambiguity.After moving VOTW to a new database platform, we developed a new VNum system. During this process GVP staff took into account the needs of the International Civil Aviation Organization (ICAO) and other stakeholders to have numbers compatible with modern computing systems. Holocene, Pleistocene, and Tertiary volcanoes all fall under the new unified numbering system, allowing interoperability between VOTW and new databases under development globally (e.g. WOVOdat, LaMEVE). Letters and characters (hyphens and equals signs) have been eliminated. Secondary numbers have been added for subfeatures associated with each volcano. None of the new numbers start with 0 or 1 to avoid confusion with the legacy system. While a connection remains to the older system, the geographic link to CAVW regions and subregions is no longer mandatory.We feel that this change is in the best long-term interest of the community.