Boulder Dislodgement During Coastal Storms and Tsunamis: Insights From a New Ensemble Model

Abstract Boulders are excellent candidate deposits to study coastal inundation events by storms and tsunamis due to their significant preservation potential. However, it is difficult to infer how and what forcing dislodged the boulder. We present a new model that enables ensemble and Monte‐Carlo‐type simulations to study the sensitivity of boulder, the fluid flow, and environmental parameters. Our examples show that boulder transport is complex and nonlinear, and to acknowledge the uncertainties of the boulder's preexisting transport conditions, a range of velocities and environmental parameters should be used to quantify the flow that caused boulder dislodgement. Key Points Hydrodynamic conditions in storms or tsunamis are difficult, if not impossible, to assess for boulder movement, especially for past events The model for boulder dislodgement takes important parameters from parameter distributions, allowing for the uncertainty assessments Boulder dislodgement is complex and requires lift and drag work in concert, especially when the center of mass is below the rotation point