Counting Alaska Volcanoes

As the Alaska Volcano Observatory matures, a refereed, consistent list of vents, volcanic centers, and historically active volcanoes is needed. Previously published lists of Alaska volcanoes are often fundamentally different from each other in what they seek to describe; sometimes possess internal inconsistencies; and do not include recent activity and recently recognized volcanoes. The Geologic Database of Information on Volcanoes in Alaska (GeoDIVA) is a uniquely thorough resource which can be used to count, categorize, and qualify volcanic features and events using explicit standardized criteria. Using traditional groupings of separate and dependent volcanoes, defining the term "eruption" to include both magmatic and phreatic eruptions, and further including suspected eruptions, persistent fumaroles, measured volcanic deformation, and volcanic-related earthquake swarms as evidence of activity, we can refine the volcano count. Alaska has about 140 Quaternary volcanoes, 94 of which had Holocene activity, 52 of which have been historically active (1700 CE to present), and 28 of which have had historical magmatic eruptions. These numbers are as much as 20% higher than similar numbers from existing published lists. To better understand Alaska volcanoes we are working to identify every individual vent. Once all known vents have been identified and compiled, we will establish explicit criteria for hierarchical categorization of vents and groups of vents. Using these, and impartially applied qualifiers describing age and type of volcanic activity, we will derive more robust answers to the questions of how many volcanoes are in Alaska, and how many of those have been active in recorded history.