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A two‐year dataset of coastal cliff microseismic ground motions is used to explore energy transfer to a cliff. The long‐term dataset enables us to characterise cliff motion responses to a wide range of environmental processes and examine whether short‐term characteristics are representative of the long‐term. We examine whether cliff‐top motions are reliable proxies for environmental processes to inform future investigations into the drivers of erosion. The study is based at an actively eroding, macrotidal, hard rock cliffed coast where considerable intra‐annual variability in wave, tide, and storm conditions permit the examination of a full range of environmental permutations. Three frequency bands of ground motion are identified that represent wind and wave processes that transfer energy to the cliff. Examining mean energy transfer by aggregating the frequency bands by sea water elevation reveals a notable departure from tidal inundation duration alone, of relevance to understanding the timing, duration and intensity of effective processes of erosion. Peak energy transfer to the cliff face occurs during the largest storms where water levels significantly exceed those of tidal inundation rather than at locations most frequently inundated by tides. We anticipate it is therefore these conditions that are likely to be most effective in eroding hard rock coasts, rather than periods which accrue energy transfer associated with still or calm waters, and hence tidally modulated inundation may not relate well to coastal erosion. Promisingly, despite signal overlap and noise, cliff‐top motions can be used as proxies for the processes that transfer energy to the coast. Coastal cliff microseismic motions as proxies for environmental processesTidal inundation duration does not depict marine energy transfer distribution

Earthquakes trigger widespread landsliding in tectonically active landscapes. The effects of strong ground shaking on hillslope stability persist into the post‐seismic stage; rates of landsliding remain elevated in the years following an earthquake. The mechanisms that control the spatial pattern and rate of ongoing landsliding are poorly constrained, hindering our ability to reliably forecast how landscapes and landslide hazard evolve. To address this, we undertook a detailed geotechnical investigation in which we subjected representative rock samples to dynamic loading, simulating the effects of earthquake ground shaking on hillslopes of different configuration. Our results indicate that post‐seismic hillslope strength is not an intrinsic rock property; rather, it responds to the amplitude of imposed dynamic loads and the degree of pre‐existing shear surface formation within the rock. This path‐dependent behavior results from differences in the character of fractures generated by dynamic loads of different amplitude, and the ways in which apertures are mobilized or degraded in subsequent (post‐seismic) shearing. Sensitivity to dynamic loading amplitude is greater in shallow landslides in which shear surfaces are yet to fully form; such hillslopes can be strengthened or weakened by earthquake events, depending on their characteristics. In contrast, deeper landslides on steeper hillslopes in which shear surfaces have largely developed are less likely to display differences in behavior in response to dynamic loading because strain accumulation along pre‐existing fractures is dominant. Our results demonstrate the need to consider path‐dependent hillslope stability in numerical models used to forecast how landscapes respond to earthquakes and how post‐seismic hazard evolves. Landsliding is more common in the months and years after an earthquake. Our understanding of why this happens is limited but likely results from earthquake weakening of hillslopes. The mechanisms causing this weakening are difficult to assess at the landscape scale using satellite imagery. An alternative approach to improve our understanding of the controls on rock strength after an earthquake is to subject rock samples to seismic shaking in laboratory conditions. We used a custom‐built apparatus to subject rock samples to pressure conditions typical of those experienced in shallow and deep‐seated landslides. We simulated ground shaking of differing intensity to assess whether the rock was weaker or stronger after the shaking stopped. In simulated shallow landslides, ground shaking intensity affected how the sample cracked. Less intense shaking weakened the rock, implying it is more likely to fail following an earthquake. Conversely, more intense ground shaking strengthened the rock by creating a very uneven sliding surface, suggesting it is less likely to subsequently fail. Simulated deeper landslides on steeper hillslopes did not weaken, displaying less sensitivity to ground‐shaking intensity. Our findings improve understanding of how hillslopes respond to seismic shaking, assisting forecasts of how landscapes and hazard develop after an earthquake. We used novel geotechnical testing to explore mechanisms that control post‐seismic hillslope strength and rheology in brittle rocksThe amplitude of dynamic loading can govern the nature of fractures and asperities formed, affecting subsequent shear strength and rheologyThe shear deformation mechanism mobilized determines whether post‐seismic shear strength increases, decreases or remains unchanged We used novel geotechnical testing to explore mechanisms that control post‐seismic hillslope strength and rheology in brittle rocks The amplitude of dynamic loading can govern the nature of fractures and asperities formed, affecting subsequent shear strength and rheology The shear deformation mechanism mobilized determines whether post‐seismic shear strength increases, decreases or remains unchanged