Identification of Coastal Sand Deposits From Tsunamis and Storm Waves Based on Numerical Computations

Abstract

Paleotsunami sand deposits are useful for identifying frequency and magnitude of past tsunami events (e.g., G. A. Dawson & Shi, 2000) and consequently serve as a proxy for imminent threat arising from possible future events. Similarly, storm deposits can provide evidence of past catastrophic coastal storms (Morton & Sallenger, 2003). However, both tsunamis and storm waves can form similar deposits (e.g.,

A Numerical Modeling Approach for Better Differentiation of Boulders Transported by a Tsunami, Storm, and Storm‐Induced Energetic Infragravity Waves

“…Even if energetic IG waves are generated, storm boulder transport distances are smaller than tsunami boulder transport distances in both the planar and reef topographies (Figure 2), as in the case of sand deposits (e.g., Watanabe et al., 2021). Thus, a longer transport distance can be crucial in differentiating tsunami and storm boulders, even if energetic IG waves are generated.…”

Sediment Transport Modeling Based on Geological Data for Holocene Coastal Evolution: Wave Source Estimation of Sandy Layers on the Coast of Hidaka, Hokkaido, Japan

“…The importance of coastal topography in STM was emphasized using 2D modeling with different slopes (Gusman et al., 2012; Watanabe et al., 2021). The I and S areas have different coastal topography on the coastline, beach ridge height, and the river mouth (Figures 1e and 1f).…”

“…STM is affected by topographic and sediment conditions, in addition to the wave height (Apotsos, Gelfenbaum, et al., 2011; Gusman et al., 2012, 2018; Li et al., 2012, 2014; Sugawara, 2019; Sugawara, Takahashi, & Imamura, 2014, 2019; Watanabe et al., 2017, 2021). Therefore, we performed sensitivity tests in the realistic parameter ranges that may have affected STM (Table 1).…”

“…Modern tsunami deposit studies have reported cases where the sand distribution does not correspond to the inundation area (Abe et al., 2012). The numerical simulation of sediment transport using extreme waves is a solution to these problems (Sugawara et al., 2019; Watanabe et al., 2018, 2021). Because directly comparing the distribution of sand layers with simulated tsunami inundation is impossible, tsunami propagation and the associated sediment transport modeling (STM) have attracted considerable attention from researchers (Sugawara, Goto, & Jaffe, 2014).…”

Can Mud Deposits Indicate Inundation Extent of Paleotsunamis? Insights From Sediment‐Transport Simulations for Sand and Mud

“…This study used 0.2 mm (2.0 phi) for sand sediment, the intermediate value of the observed grain size for sand deposits. Indeed, many previous studies simulated sediment transport using a single grain size and revealed that such simulation could explain the observed distribution (e.g., Apotsos et al., 2011a, 2011b; Sugawara et al., 2014; Watanabe et al., 2018, 2021). The observed grain size of the mud tsunami deposit in the Sendai plain is 4.0–6.82 phi (Chagué‐Goff et al., 2012).…”