Impact of nested moisture cycles on coastal chalk cliff failure revealed by multi seasonal seismic and topographic surveys

This is a Preprint and has not been peer reviewed.

Downloads

Download Preprint

Supplementary Files
Authors

Michael Dietze , Kristen L. Cook, Luc Illien, Oliver Rach, Stephanie Puffpaff, Ingolf Stodian, Niels Hovius

Abstract

Cliff failure is a fundamental process shaping many coastlines worldwide. Improved insight into direct links between cliff failure and forcing mechanisms requires precise information on the timing of individual failures, which is difficult to obtain with conventional observation methods for longer stretches of coastline. Here we use seismic records and auxiliary data spanning 25 months to precisely identify and locate 81 failure events along the 8.6-km long chalk cliff coast of Jasmund, on Germany’s largest island, Rügen. The sub-minute precision of event timing allows the linkage of individual failures to triggers over a wide range of relevant time scales. We show that during the monitoring interval, marine processes were negligible as a trigger of cliff failure, although still being important for the removal of resulting deposits. Instead, cliff failure was associated with terrestrial controls on rock moisture. Most failures occurred when water caused a state transition of the cliff forming chalk, from solid to liquid. Water content was modulated by: i) subsurface flow towards the cliff, ii) rain onto the cliff, and iii) condensation of atmospheric moisture, leading to clustered failures preferentially during the night. Seasonal water availability, controlled by plant activity, imposed an annual cycle of cliff failure, and wetter and drier than average years imposed a month-long legacy effect on cliff failure dynamics. Similar terrestrial control mechanisms may also be relevant for other coastal chalk cliffs, in addition to already investigated marine triggers.

DOI

https://doi.org/10.31223/osf.io/wuvdr

Subjects

Earth Sciences, Geomorphology, Physical Sciences and Mathematics

Keywords

Dates

Published: 2020-01-09 08:53

Last Updated: 2020-06-26 07:16

Older Versions
License

CC0 1.0 Universal - Public Domain Dedication

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.