More Than Meets the Eye: Volcanic Hazard Map Design and Visual Communication

Abstract

Volcanic hazard maps depict areas that may be affected by dangerous volcanic processes, such as pyroclastic density currents, lava flows, lahars, and tephra fall. These visualisations of volcanic hazard information are used to communicate with a wide variety of audiences both during times of dormancy and volcanic crisis. Although most volcanic hazard maps show similar types of content, such as hazard footprints or zones, they vary greatly in communication style, appearance, and visual design. For example, maps for different volcanoes will use different combinations of graphics, symbols, colours, base maps, legends, and text. While this variety is a natural reflection of the diverse social, cultural, political, and volcanic settings in which the maps are created, crises and past work suggest that such visual design choices can potentially play an important role in volcanic crisis communication by influencing how people understand the hazard map and use it to make decisions. Map reading is a complex process, in which people construct meaning by interpreting the various visual representations within the context of their information needs, goals, knowledge, and experience. Visual design of the map and the characteristics of the hazard map audience can therefore influence how hazard maps are understood and applied. Here, we review case studies of volcanic crises and interdisciplinary research that addresses the relationship between hazard maps, visual design, and communication. Overall, this growing body of work suggests that volcanic hazard maps can be very useful visual tools for crisis communication if they are designed in a way that provides clear and useful information for the audience. Further, while it is important that each map is designed for its unique situation and setting, engaging with hazard map audiences to better understand their information needs and considering lessons learnt from interdisciplinary work on visual communication can help inform and guide knowledge exchange using maps.

Integrating Volcanic Hazard Data in a Systematic Approach to Develop Volcanic Hazard Maps in the Lesser Antilles

“…Other studies have shown how design elements such as colour, symbology, data classification (e.g., stretched vs. binned), map content (including borders, landmarks etc. ), and use of gradational shading can significantly affect the way in which users interpret information on a map (e.g., Monmonier, 1996;Olson and Brewer, 1997;Severtson and Vatovec, 2012;Thompson et al, 2015Thompson et al, , 2017Cheong et al, 2016). Our personal experience has also shown this to be the case.…”

“…Developing a volcanic hazard map is challenging, as it requires consideration and integration of a vast array of information into a single graphical image, including past eruptive activity, topography, weather patterns, any available modelling data, time frames for volcanic hazard analyses, quality of data, and associated uncertainties, as well audience-specific map elements and design features (e.g., Thompson et al, 2017). The different strands of information available for the development of any given volcanic hazard map are thus diverse in terms of origin and type of data, methodologies involved in their generation and the associated uncertainties.…”

Assessing the impact of road segment obstruction on accessibility of critical services in case of a hazard

“…A lava flow invasion hazard map identifies the locations that may be affected by a lava flow within a given time period (De La Cruz-Reyna et al, 2000;Sigurdsson et al, 2015;Thompson et al, 2017). The one used in this study provides for each location (corresponding with a cell of 90 m resolution) a probability of being inundated by lava flow during the next eruption (Fig.…”

“…Other studies define the road segments that are most susceptible to be affected depending on their location relative to historical hazard zones (Sohn, 2006) or their closeness to areas having a high susceptibility to host a hazard (Postance et al, 2017). Probabilistic hazard maps provide relevant information about the probability of given areas to be affected by a hazard and methods to produce such maps have developed significantly over the last years, e.g., for lahars (Bartolini et al, 2014;Sandri et al, 2014), landslides (Alexakis et al, 2014), earthquakes (Yazdani and Kowsari, 2017), pyroclastic flows (Bartolini et al, 2014;Sandri et al, 2014;Tierz et al, 2016), lava flows (Becerril et al, 2014;Favalli et al, 2009Favalli et al, , 2012 and tephra (Becerril et al, 2014;Bonadonna et al, 2005;Sandri et al, 2014). Such maps are produced by combining data on historical events with physical or statistical modeling (Calder et al, 2015).…”

Assessing road segment impact on accessibility to critical services in case of a hazard

“…A lava flow invasion hazard map identifies the locations that may be affected by a lava flow within a given time period (De La Cruz-Reyna et al, 2000;Sigurdsson et al, 2015;Thompson et al, 2017). The one used in this study provides for each location (corresponding with a cell of 90 m resolution) a probability of being inundated by lava flow during the next eruption ( Figure 3).…”