Dr. Aranguiz-Muñoz, Rafael

The destructive potential of a massive tsunami is not only related to society’s response capacity and evacuation plans, but also to the urban morphology and land cover. The Boca Sur neigh- borhood is one of the areas in central Chile that is most exposed to tsunamis, and it is framed in the context of increasing urban growth. Faced with the worst tsunami scenario (earthquake Mw = 9.0), residents’ evacuation potential is analyzed by using a least-cost-distance model, and two scenarios of land cover change are considered (2002 and 2018). Presently, the sector’s urban areas have grown by 83%, therefore its population has also grown. The evacuation times consider an average walking speed (1.22 m/s) for both years (2002 and 2018). This analysis establishes that over 40% of the study area is more than 60 min away from the safe zones established by authorities. This differs greatly from the 22-min average tsunami arrival time. Moreover, 19% of the area could not be evacuated in less than 30 min. Therefore, it can be concluded that the increased urbanization in the coastal area has not improved travel times, as urban planning did not consider the optimization of evacuation times to the designated safe zones. In this study, we propose new safe zones that would help reducing evacuation times to 30 min. In addition to the area’s high tsunami risk, the evacuated population’s strong travel time limitations are added, prioritizing the incorporation of social and urban resilience elements that help to effectively reduce the risk of disaster, by using land-use planning and community work.

On September 28, 2018 significant tsunami waves, which are considered to have been generated by submarine landslides, struck the shorelines of Central Sulawesi, Indonesia. One month after the event, the authors conducted a questionnaire survey of the affected areas (Donggala Regency and Palu City) to collect information on the evacuation behaviour and tsunami awareness of local residents. In the present study, in addition to summarising the overall trend of the survey results using descriptive statistics, a chi-squared test was applied to analyse the significance of the relationship between tsunami awareness and evacuation behaviour and the demographic characteristics of respondents. The analysis of the results demonstrates that although the respondents generally have a high level of tsunami awareness, younger people and Donggala Regency residents have an overall lower understanding of the phenomenon. It was also found that 82.5% of the population evacuated after witnessing others evacuating during the event. As there was no official warning to residents before the arrival of the tsunami, this social trigger played a significant role in prompting evacuation and decreasing the number of casualties. The present study also revealed that many people faced congestion while evacuating (especially in Palu City). This highlights the need to introduce additional tsunami disaster mitigation strategies to ensure that all residents can swiftly evacuate during such incidents.