# Reconstructing the 26 June 1917 Samoa Tsunami Disaster
## 5 Discussion  
Our results suggest that the south coast of Savai'i including parts of south Upolu were affected by the 1917 tsunami. A comparison of the historic evidence with the modelled inundation shows some inconsistencies. For example, observations of runup in the village of Lotofaga in southeast Upolu indicate that half of the village was submerged [4; 31], which suggests significantly greater inundation extent and flow depth in Lotofaga than what our model reproduces. That is, the modelled inundation suggests that Lotofaga was not severely impacted. This inconsistency likely reflects the simplicity in our tsunami source model in the light of recent evidence of complex behaviour at'subduction-zone bends', as is the case at the northern Tonga Trench [26]. In addition, records of the maregram of Apia harbour indicated initial water level fluctuations only 5-10 min after the earthquake compared with approximately 34 min modelled wave arrival time in Apia. The observed fluctuations of 5-10 min in Apia after earthquake initiation is highly unlikely if considering that the tsunami was generated/influenced by the earthquake source alone, which was located further west of the 2009 epicentre and farther away from Apia. However, the maregram accurately recorded the normal tides at the time of the event, which were within 14 min of tide predictions. This suggests that either the recorded timing of the tsunami or earthquake were inaccurate, or that there is more complexity in the tsunami source mechanism than what is currently captured in our modelling. For example, the possibility of complex near-simultaneous faulting source comparable with that seen for the 2009 event [25; 38; 39] has not been assessed in this study. It is also probable that the earthquake could have caused co-seismic submarine landsl close to or along the north coast of Upolu, which might explain the early fluctuations  
Figure 10: Epicentres of the 1917 and 2009 earthquakes and corresponding extents at the coast that were predominantly affected by each respective tsunami according to the models. The red crosses indicate the 1917 runup benchmarks shown in Figures 5 and 6 showing locations that should be inundated. observed in Apia harbour that cannot be accounted for using our current earthquake source mechanism (e.g., [41]). Further investigations are needed to unravel this dilemma. Of particular note is the comparison in total number of casualties between the two events. In the 2009 tsunami, 146 people lost their lives [26] and several thousand were displaced, compared with only two casualties inferred from damage descriptions in the 1917 event [32]. In contrast, the extent of inundation inferred from our modelling of the 1917 tsunami, particularly on Savai'i, suggests that damage to property, threat to life, and displacement would have been more severe than what is currently inferred from the historical records. It is plausible that loss of life may have been minimal based on the modern analogy presented by the devastating Hunga-Tonga Hunga-Ha'apai volcano-generated tsunami where three casualties along with major destruction to property, homes, and businesses, and displacement of approximately 1500 people were observed [42]. However, it is equally plausible that loss of life and human displacement far exceeded that which has been documented in historical records. Nevertheless, the hazard risk patterns presented in this study when compared with the 2009 event indicate that the 1917 tsunami would have been more severe on the island of Savai'i compared with Upolu.