# Reconstructing the 26 June 1917 Samoa Tsunami Disaster
## 6 Conclusions  
This study aimed to reconstruct the 1917 tsunami in Samoa and assess the impacts of inundation on present-day buildings and population exposure. Our findings show variable consistency between modelled-to-observed event reconstructions, which are exemplified by the inconsistency in the wave arrival time in Apia and underestimation of inundation extent/intensity in southeast Upolu. The observed discrepancies are probably due to: (1) earthquake source model and geometry configuration; (2) instrumental seismic and/or tide gauge record uncertainties for Samoa in 1917 that might explain the 20 min anomaly in the tidal reference time; (3) limited records of runup observations for validation; (4) uncertainties in potential source and/or co-seismic mechanisms that might have exacerbated the observed characteristics of the tsunami (e.g., in Apia harbour). These uncertainties represent areas for further modelling investigation. Notwithstanding these discrepancies, our modelling provides a first-order estimation to better quantify the magnitude of impacts for the 1917 tsunami inundation in Samoa that can support scenario-based hazard risk assessment. Our modelling suggests that the scale of impacts, in particular on Savai'i and with regards to potential casualties and human displacement, likely exceeded that which was recorded in historical records. However, it is equally plausible that, although the extent of property damage and displaced peoples was likely severe, the casualty rate may have been low comparable to the death toll observed in the January 2022 Hunga-Tonga Hunga-Ha'apai tsunami in Tonga. Nevertheless, comparison between the 1917 and 2009 events suggests that the extent of present-day exposure distribution around the two main islands of Samoa from local tsunamis originating at the Northern Tonga Trench is highly influenced on the earthquake epicentre and location/orientation of co-seismic displacement. That is, Savai'i Island is more exposed to tsunamis originating along the western segment of the NTT (e.g., 1917 event), compared with Upolu in the east, which exhibits greater exposure to outer-rise events originating along the east NTT segment. Conceptualization, L.S., C.B., S.W., R.P., J.C.T., M.W., L.T. and P.V. ; methodology, C.B., S.W., R.P. and L.S. ; software, C.B., R.P., L.S., S.W. and M.W. ; validation, L.S., C.B., S.W., R.P., J.C.T., M.W., L.T. and P.V. ; formal analysis, L.S., C.B., S.W., R.P., J.C.T., M.W., L.T. and P.V. ; investigation, L.S., C.B., S.W., R.P. and P.V. ; resources, S.W. and M.W. ; data curation, L.S., C.B., S.W., M.W., J.C.T. and L.T. ; writing\(-\)original draft preparation, L.S., S.W., C.B., R.P., M.W. and P.V. ; writing\(-\)review and editing, L.S., C.B., S.W., R.P., J.C.T., M.W., L.T. and P.V. ; visualization, L.S., C.B. and R.P. ; supervision, S.W., M.W. and J.C.T. ; project administration, L.S., S.W. and M.W. ; funding acquisition, S.W., L.S., M.W., P.V., J.C.T. and L.T. All authors have read and agreed to the published version of the manuscript. The APC was funded by NIWA Taihoro Nukurangi Project No: CARH2206. Not applicable. **Data Availability Statement:** Baseline topography, bathymetry, and exposure datasets used in this study as well as raw results are accessible via formal request to the Samoa Ministry of Natural Resources and Environment. The BG-Flood hydrodynamics modelling software is available on the GitHub: [[https://github.com/[PERSON]/BG_Flood](https://github.com/[PERSON]/BG_Flood)]([https://github.com/[PERSON]/BG_Flood](https://github.com/[PERSON]/BG_Flood)) (accessed on 1 June 2021), and the RiskScape multi-hazard impacts modelling software is available at: [[https://riskscape.org.nz/](https://riskscape.org.nz/)]([https://riskscape.org.nz/](https://riskscape.org.nz/)) (accessed on 28 June 2021). **Acknowledgments:** This research was supported via collaboration between NIWA Taihoro Nukurangi Natural Hazards National Science Centre (S.W. ; C.B. and R.P. ), the University of Portsmouth (L.S. and M.W.