Abstract The western coast of India is highly vulnerable to tsunami hazards due to its geographical proximity to the Makran Subduction Zone (MSZ), one of the most seismically active margins of the northern Indian Ocean. Moreover, during the Late Holocene, the Great Rann of Kachchh (GRK) along the western coast of India functioned as an extended arm of the Arabian Sea, serving both as a receptor of far-field waves and as a plausible local tsunami source due to its seismic activity that might have forced the Harappan and medieval settlements of Kachchh to reoccupy/relocate. Geological evidence, including tsunami deposits along the western Indian coastline and within the GRK, attests to repeated Holocene tsunami events and underscores the need for numerical modelling to resolve their dynamics. Here, we simulate tsunami generation, propagation, and runup under both modern and paleo-bathymetric conditions for two different sources i.e. Far-field (MSZ) and local (GRK) sourced events. To account for paleo-shoreline configurations, relative sea-level highstands of + 5 m and + 9 m were incorporated into bathymetric reconstructions. The result shows that far-field scenarios under present and elevated sea levels produce moderate wave heights (0.6–1.0 m) along western coastal margins with minimal impact on Harappan and medieval sites, whereas local scenarios amplify effects, reaching ~ 3.7 m in inland basins and ~ 1.5 m along coastal margins, significantly affecting these settlements, suggesting a direct role of tsunamis in shaping cultural and geomorphic evolution of the region. Inundation mapping reveals that only GRK events generate considerable onshore flooding at key sites, with ~ 0.5–1 m depth during Holocene highstands, matching settlement chronologies. These findings demonstrate that relative sea-level fluctuations strongly modulate tsunami hazard, highlighting the importance of integrating paleo-sea-level reconstructions with geological and archaeological records to refine long-term risk assessments and resilience strategies for vulnerable coastal populations.
Sharma et al. (Fri,) studied this question.