Criteria-based visualization design for hazard maps

Abstract

Abstract. Probabilistic seismic hazard estimates are a key ingredient of earthquake risk mitigation strategies and are often communicated through seismic hazard maps. Though the literature suggests that visual design properties are key for effective communication using such maps, guidelines on how to optimally design hazard map are missing from the literature. Current maps use color palettes and data classification schemes which have well-reported limitations that may inadvertently miscommunicate seismic hazard. We surveyed the literature on color and classification schemes to identify design criteria that have empirical support for communicating hazard information. These criteria were then applied to redesign the seismic hazard map for Germany. We isolated several communication goals for this map, including essential properties about moderate-hazard seismic regions and a critical hazard threshold related to the German seismic building codes. We elucidate our redesign process and the selection of new colors and classification schemes that satisfy the evidence-based criteria. In a mixed-methods survey, we evaluate the original and redesigned seismic hazard maps, finding that the redesign satisfies all the communication goals, and improves users’ awareness about the spatial spread of seismic hazard, relative to the original. We consider practical implications for the design of hazard maps across the natural hazards.

Visual Communication of Aftershock Forecasts Based on User Needs: A Case Study of the United States, Mexico and El Salvador

“…Given the ubiquity of location-related use cases shortly after a large earthquake, maps were seen as an immediate need directly after the mainshock, along with simplified statements that put the most important hazard first, e.g., by describing the probability of strong shaking. Strategic use of colors that connote risk (e.g., red) may assist users to quickly understand the critical spatial patterns, as supported by prior visualization research [Schneider et al, 2023]. Both shaking intensity level maps and probability of exceedance maps were seen as useful, as has been found for volcanic risk visualization [Thompson et al, 2015], though perhaps the former is more useful soon after the mainshock than the latter.…”

“…Guidance does exist for visualizing seismic hazards in general [Schneider et al, 2023] and other natural hazards (e.g., Thyng et al [2016]). However, these guidelines make no connection to the needs of users of this information, nor are they evaluated by such users.…”

The communication strategy for the release of the first European Seismic Risk Model and the updated European Seismic Hazard Model

“…To design user-centred products, testing is indispensable (Dallo et al, 2022a;Karjack et al, 2022;Marti et al, 2023;Schneider et al, 2022). The earthquake hazard and risk maps of Europe were two of the main products that were also integrated into many other products (e.g., flyers, posters).…”

“…The earthquake hazard and risk maps of Europe were two of the main products that were also integrated into many other products (e.g., flyers, posters). Maps are commonly used to communicate spatial hazard and risk but are only an appropriate format if they are well designed (Marti et al, 2019;Schneider et al, 2022). Experiences show that colour scales are often chosen based on subjective preferences and not empirical evidence (Thompson et al, 2015).…”

“…Robertson and O'Callaghan (1986) further recommend using linear progressions in colour lightness across the entire scale in order to guarantee perceptual uniformity (i.e., a unit increase in data value corresponds to a unit increase in the perception of change between colours). Schneider et al (2022) additionally provide a criteria-based framework for the design of hazard maps demonstrated by the design of the German seismic hazard map (Grünthal et al, 2018). However, for cross-country maps one must also take into account that what people associate with specific colours is cultural-specific (Wang et al, 2014).…”