Effects of Source Faulting and Fringing Reefs on the 2009 South Pacific Tsunami Inundation in Southeast Upolu, Samoa

Abstract

Local observations of nearshore and runup processes provide the evidence base for refining and improving source parameters through forward tsunami modeling (e.g., Davies, 2019; Yamazaki et al., 2018). Such improvements can lead to more realistic tsunami hazard representations and a better understanding of local processes for use in coastal management planning.

Multiscale Quantification of Tsunami Hazard Exposure in a Pacific Small Island Developing State: The Case of Samoa

“…The 2009 SPT represents a maximum likely local event and was the second most devastating disaster in this region over the preceding century in terms of loss of life and trauma, i.e., second only to the 1918 influenza pandemic disaster [28]. While Samoa is known to have experienced far-field tsunamis such as that from the 1960 Valdivia event [29], the overall threat to safety from far-field tsunamis is much lower compared with local events which can impact the shores of Samoa in less than 20 min (e.g., [14,30]).…”

“…The recent acquisition of 1 and 5 m gridded LiDAR topography and near-shore bathymetry for the whole of Samoa [36] now enables the development of more detailed hazard and risk assessments. For example, the work presented in [14] provides a characteristic set of 2009-type tsunami analogies (or hazard models), which can be applied to scenario-based exposure assessments (e.g., [37][38][39]), a key focus of this study.…”

“…A significant proportion of SIDS populations and business hubs in the central Pacific are in coastal low-lying areas which are vulnerable to the impacts of tsunamis [10]. This was clearly demonstrated by the 2009 South Pacific tsunami (SPT) which impacted the Independent State of Samoa (herein Samoa) [11][12][13][14], causing widespread loss of life and infrastructure damage along the southern shores of Upolu and Savaii islands [15][16][17][18][19] (Figure 1). While planning tools to support tsunami resilience in Samoa have been developed, such as identifying evacuation and hazard mitigation zones (e.g., [20,21]), these were purposefully designed to be conservative and derived using relatively coarse datasets.…”

“…The aim of this study is to quantify and assess the influence which tsunami inundation model resolution has on multiscale exposure distributions of built elements at risk. We apply representations of the 2009 SPT hydrodynamic model developed in [14], as well as digital representations of buildings and roads to quantify risk exposure distributions across multiple sociopolitical levels. The key objectives are to: (1) apply a scenario-based approach to assess building and road exposure to model 2009 SPT inundation at 50 and 10 m grid resolution as developed by [14]; and (2) to demonstrate the influence of inundation model resolution on exposure distributions at national, district, and village levels, and how these can support preparedness planning.…”

“…We apply representations of the 2009 SPT hydrodynamic model developed in [14], as well as digital representations of buildings and roads to quantify risk exposure distributions across multiple sociopolitical levels. The key objectives are to: (1) apply a scenario-based approach to assess building and road exposure to model 2009 SPT inundation at 50 and 10 m grid resolution as developed by [14]; and (2) to demonstrate the influence of inundation model resolution on exposure distributions at national, district, and village levels, and how these can support preparedness planning. We discuss the suitability of model resolution in rapid tsunami risk exposure analysis as well as the implications of our findings within the context of tsunami preparedness and evacuation planning.…”