Earthquake report maps play a crucial role in communicating vital seismic information to the public and emergency personnel. However, the lack of unified global standards often leads to misunderstandings and confusion. This study aims to identify the most effective visual variables in earthquake report maps to enhance user comprehension and perception, ultimately improving public safety during seismic events. This research employs a mixed-method approach, analyzing existing earthquake report maps from countries in the Pacific Ring of Fire and conducting a controlled experiment with 40 participants. Using Japan’s official map as a benchmark, we tested 8 variants, manipulating overlays, transparency, and numerical seismic intensity. Participants’ understanding was evaluated through questionnaires, the Cognitive Load Scale (CLS), the Interactive Visual Cognition (IVC) design principle detection tool, and semi-structured interviews. Statistical analysis reveals that designs incorporating numerical intensity significantly improve accurate information transmission and user satisfaction, particularly in emergency situations where they can quickly support decision-making. The application of transparency effectively reduces visual interference, making place names and background information clearer. However, when transparency and overlays lack numerical assistance, information becomes muddled, reducing comprehension. Furthermore, overlays help emphasize earthquake distribution but may obscure information and should be carefully combined with other visual parameters. The study recommends that future earthquake report map designs should emphasize concise information delivery and interactive design, such as allowing users to filter low-intensity areas or zoom into specific regions. This research provides an empirical foundation and practical guidelines for the design of earthquake visualization tools, aiming to enhance the efficiency of seismic information transmission and user experience.