Coastal cliff ground motions and response to extreme storm waves

TitleCoastal cliff ground motions and response to extreme storm waves
Publication TypeJournal Article
Year of Publication2015
AuthorsEarlie CS, Young AP, Masselink G, Russell PE
JournalGeophysical Research Letters
Date Published2015/02
ISBN Number1944-8007
Keywords0933 Remote sensing; 1817 Extreme events; 3025 Marine seismics; 4546 Nearshore processes; cliff-top displacements; cliff-top wave overtopping; coastal erosion; extreme waves; Microseismic ground motion; Terrestrial Laser Scanning

Coastal cliff erosion from storm waves is observed worldwide but the processes are notoriously difficult to measure during extreme storm wave conditions when most erosion normally occurs, limiting our understanding of cliff processes. Over January-February 2014, during the largest Atlantic storms in at least 60 years with deep water significant wave heights of 6 – 8 m, cliff-top ground motions showed vertical ground displacements in excess of 50 – 100 μm; an order of magnitude larger than observations made previously. Repeat terrestrial laser scanner surveys over a 2-week period encompassing the extreme storms gave a cliff face volume loss 2 orders of magnitude larger than the long-term erosion rate. The results imply that erosion of coastal cliffs exposed to extreme storm waves is highly episodic and that long-term rates of cliff erosion will depend on the frequency and severity of extreme storm wave impacts.

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