Analysis of environmental controls on tsunami deposit texture

• We constructed a database of tsunami deposit location, grain size and environmental factors.
• We assess relationships between these factors using statistical analysis.
• Significant relationships exist between grain size, density, climate and coastal protection.
• Cluster analysis groups deposits by grain size, then sediment density and climate.
• Statistics is an underutilised tool for exploring existing tsunami databases.

Tsunamis transport large amounts of sediment and can leave recognisable signatures in the landscape. The form and composition of onshore tsunami deposits are a function of wave dynamics, sediment availability and characteristics of the local environment, the latter of which also partially controls preservation of the deposit. This research reviews these relationships in a global context and assesses the connection between tsunami deposit particle size and four controlling parameters: climate (temperature and rainfall), density of tsunami sediments, degree of coastal protection and distance between tsunami source and sediment deposition. An international dataset of tsunami deposit locations and texture was compiled from published literature and existing databases. Values for environmental variables were calculated for each location from global datasets of temperature, rainfall, coastline shape and tsunami source locations. Spearman's rank-order correlation, Principal Component Analysis (PCA) and hierarchical Cluster Analysis (CA) were used to analyse relationships between these variables. PCA results show an inverse relationship between particle size and sediment density, climate variables and distance from source. CA results support this, suggesting a cluster structure controlled primarily by particle size and secondly by climate and sediment density. These relationships can be explained by the influence of the environment on antecedent morphology and the composition of sediments available for tsunami transport.