Although the size-frequency distributions of icebergs can provide insight into how they disintegrate, our understanding of this process is incomplete. Fundamentally, there is a discrepancy between iceberg power-law size-frequency distributions observed at glacial calving fronts and lognormal size-frequency distributions observed globally within open waters that remains unexplained. Here we use passive seismic monitoring to examine mechanisms of iceberg disintegration as a function of drift. Our results indicate that the shift in the size-frequency distribution of iceberg sizes observed is a product of fracture-driven iceberg disintegration and dimensional reductions through melting. We suggest that changes in the characteristic size-frequency scaling of icebergs can be explained by the emergence of a dominant set of driving processes of iceberg degradation towards the open ocean. Consequently, the size-frequency distribution required to model iceberg distributions accurately must vary according to distance from the calving front.

Linking hard rock coastal cliff erosion to environmental drivers is challenging, with weak relationships commonly observed in comparisons of marine and subaerial conditions to the timing and character of erosion. The aim of this paper is to bring together datasets to explore how best to represent conditions at the coast and to test relationships with erosion, which on this coast is primarily achieved via rockfalls. On the N. Yorkshire coast in the UK we compare a continuously monitored microseismic dataset, regionally monitored coastal environmental conditions, modelled at-cliff conditions and periodic high-resolution 3D monitoring of changes to the cliff face over a 2-year period. Cliff-top microseismic ground motions are generated by a range of offshore, nearshore and at-cliff sources. We consider such ground motions as proxies for those conditions that promote the occurrence of rockfalls and erosion. Both these data and modelled at-cliff water levels provide improved insight into conditions at, and wave energy transfer to, the cliff. The variability in microseismic, modelled and regionally-monitored environmental data derives statistically 2 significant relationships with increases in the occurrence of rockfalls. The results demonstrate a marine control on the total volume and size characteristics of rockfalls. The strongest relationships found are with rockfalls sourced from across the entire cliff, rather than just at the toe, indicating that the marine influence, albeit indirectly, extends above and beyond the area inundated. These results identify failure mechanisms driving erosion, where a range of processes unique to the coast trigger failure, but in a manner beyond purely wave action at the cliff toe. Greater erosion occurs at the cliff toe. However, comparing water level inundation frequency, microseismic energy transfer and erosion, we observe that heights up the cliff that correspond with water levels associated with low frequency, high energy storms, or more frequent inundation, do not experience increased erosion. Our results describe the relationship between inundation duration, energy transfer and erosion of hard rock cliffs, and illustrate the relative intensity of erosion response to variations in these conditions. Implicitly our data suggests that in future, cliffed rocky coasts may be relatively quick to respond to changes in environmental forcing.

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The alongshore distribution of wave energy is believed to be an important control on the spatial variability of coastal erosion. There is, however, a lack of field data quantifying the alongshore variability in wave energy on rock coasts, whereby the relative control of coastline geometry versus foreshore characteristics on wave energy delivery remains unclear. A number of studies have identified high-frequency cliff-top ground shaking to be generated by wave impacts at the cliff toe during high tides (HT). To capture the variability of wave-cliff impact energy along-coast, we installed an array of cliff-top seismometers along a 1 km stretch of coastline in North Yorkshire, UK. Our aim is to constrain how wave energy transfer to the cliff toe varies, and to examine the relative energy transfer around typical coastline features, including a bay and headlands. Whilst the greatest HT ground motion energy is recorded at a headland and the lowest at the centre of the bay (5% of that observed at the headland), we identify no systematic alongshore variation in the HT ground motion energy that can be related to coastline morphology. We also note considerable variation between features of similar form: the total HT ground motion energy at one headland is only 49% of the next headland 1 km alongshore. Between neighbouring sites within the bay, separated by only 100 m, we observe up to an order of magnitude difference in ground motion energy transfer. Our results demonstrate the importance of the foreshore in driving the variations in energy delivery that we observe. Local alterations in water depth and foreshore topography control the alongshore distribution of wave energy available to generate cliff HT ground motions. Importantly, this apparently local effect overrides the influence of macroscale coastal planform morphology, which has previously been assumed to be the dominant control. The results show that foreshore characteristics that hold influence over wave energy transfer vary significantly over short (~100 m) distances, and so we expect erosion controlled by wave impacts to vary over similar scales.

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