Megathrust Earthquakes Amplify Coastal Wave Hazards in Cascadia Under Rising Sea Levels
Abstract
Along the Cascadia Subduction Zone, destructive megathrust earthquakes represent a significant coastal hazard. These events generate abrupt coseismic subsidence, instantaneously increasing relative sea level. In the coming decades, global sea level rise will continue to shift baseline coastal conditions, potentially enhancing earthquake-driven hazards. Here, we model how sea level rise, wave climate, and the magnitude and timing of earthquake-driven subsidence interact to influence nearshore wave dynamics along the Cascadia margin. We find that coseismic subsidence amplifies shoreline wave power by shifting wave action landward despite reductions in wave breaking. This amplification is strongly controlled by shore platform slope, with negligible increases along steep shores and up to a million-fold increase in wave power for low-gradient sites. These changes highlight the potential for drastic increases in coastal erosion following future earthquakes. The timing and persistence of these hazards strongly depend on the sea level trajectory. Under a high-emissions scenario, accelerated sea level rise shifts the window of maximum earthquake-driven wave amplification earlier in the century, increasing the potential of post-event coastal recovery. Our results demonstrate that interactions between climate and solid Earth geohazards create transient, but potentially long-lived, shifts in coastal wave energy regimes that can shape future hazards and landscape evolution.
Related
- Multi-lake turbidite records of Chilean megathrust earthquakes: Refining the use of turbidite volume as paleoseismic proxy
- Asthenosphere rheology and the continental-scale interseismic deformation driven by repeated megathrust earthquakes: Insights from the South American plate
- Widespread On‐Fault Geologic Evidence for Variable Mode Coseismic Slip to the Trench in Cascadia
- Seismic and tsunami hazard potential of the Negros–Sulu megathrust, Philippines
- Self-arresting and runaway earthquakes: Nucleation, propagation, Gutenberg-Richter law, and dragon-king events
BibTeX
@misc{lopez2026megathrust,
title = {{Megathrust Earthquakes Amplify Coastal Wave Hazards in Cascadia Under Rising Sea Levels}},
author = {Cesar Gavrie Lopez and Claire C Masteller},
howpublished = {EarthArXiv},
year = {2026},
month = sep,
doi = {10.31223/x59z17},
url = {https://eartharxiv.org/repository/view/14720/},
note = {CC BY-NC 4.0},
}
RIS
TY - UNPB
TI - Megathrust Earthquakes Amplify Coastal Wave Hazards in Cascadia Under Rising Sea Levels
AU - Cesar Gavrie Lopez
AU - Claire C Masteller
PY - 2026
DA - 2026/09/01
PB - EarthArXiv
DO - 10.31223/x59z17
UR - https://eartharxiv.org/repository/view/14720/
AB - Along the Cascadia Subduction Zone, destructive megathrust earthquakes represent a significant coastal hazard. These events generate abrupt coseismic subsidence, instantaneously increasing relative sea level. In the coming decades, global sea level rise will continue to shift baseline coastal conditions, potentially enhancing earthquake-driven hazards. Here, we model how sea level rise, wave climate, and the magnitude and timing of earthquake-driven subsidence interact to influence nearshore wave dynamics along the Cascadia margin. We find that coseismic subsidence amplifies shoreline wave power by shifting wave action landward despite reductions in wave breaking. This amplification is strongly controlled by shore platform slope, with negligible increases along steep shores and up to a million-fold increase in wave power for low-gradient sites. These changes highlight the potential for drastic increases in coastal erosion following future earthquakes. The timing and persistence of these hazards strongly depend on the sea level trajectory. Under a high-emissions scenario, accelerated sea level rise shifts the window of maximum earthquake-driven wave amplification earlier in the century, increasing the potential of post-event coastal recovery. Our results demonstrate that interactions between climate and solid Earth geohazards create transient, but potentially long-lived, shifts in coastal wave energy regimes that can shape future hazards and landscape evolution.
ER -