An early version of this database (Ogburn et al. unpublished; Calder et al. 2015) originally tried to classify maps in 5 categories: geology-based, integrated (bulls-eye), administrative, simple modeling-based, and probabilistic modeling-based. Throughout the course of the IAVCEI Commission on Volcanic Hazards and Risk (CVHR) State of the Hazard Map workshops, however, it was realized that more categories were needed to fully classify maps and that these original categories mixed aspects of map methodology (geology-based, modeling-based) with hazard zone presentation (integrated, administrative).
The Volcanic Hazard Maps Database now classifies maps according to a variety of map aspects including:
- Hazard Process Type: which hazard processes (e.g. lahar, lava flow) are represented on the map?
- Hazard Zone Presentation: are hazard processes combined into hazard level-focused zones (e.g. high-medium-low hazard) or are hazard processes separated into hazard process-focused zones (e.g. lahar hazard zone, lava flow hazard zone)?
- Temporal Scale: is the map intended to serve for a long time as a background hazard map or was the map created during or for a short-term crisis?
- Spatial Scale: does the map cover the volcano, an entire region, or just a flank or drainage?
- Publication Format: what is the original physical format of the map? Is it a map sheet or poster, a sign, a flyer, a figure in a journal, an insert in a hazard assessment, or an interactive website?
- Zonation Methodology: what methods were used to assess hazard and create zones? If the map was based on modeling, what models were used?
- Scenario Types: is the map based on the most-likely or worst case scenario? On a certain size or style eruption? On a specific previous eruption? On a certain season, vent location, or eruption composition?
- Hazard Zone Labels and Probability definition: how are the hazard zones defined and labeled? How is probability defined? Are zones defined by the hazard process name, the qualitative probability (e.g. high-medium-low), using numeric probabilities, or estimated values or Hazard Impact Metrics (e.g. ash thickness)?
- Purpose and Audience: what was the intended purpose of the map (e.g. hazard awareness, crisis management, land-use planning, scientific interest)? Who was the intended audience (e.g. the public, emergency managers, government planners, scientists)?
- Language: what language or languages is the map presented in?
- Map Design and Cartographic Elements: what color scheme, basemap type, dimensionality or view style (2D plan view, 3D perspective view), and layout is used? What cartographic or other map elements are included (e.g. evacuation routes, hazard arrival times, actions to take, uncertainty visualization)?
In this way, maps can be categorized using all or some of these categories. For example, a volcanic hazard map can be classified according to its most salient characteristics or according to user needs, and thus be an “hazard process-focused, English-language, long-term, modeling-based map” or a “worst-case scenario, poster-style, lahar hazard map”.