Systematic slowing of initially rapid retreat of new coasts formed by historical eruptions in volcanic islands

Zhao, Zhongwei, Mitchell, Neil C., Quartau, Rui and Ramalho, Ricardo S. 2025. Systematic slowing of initially rapid retreat of new coasts formed by historical eruptions in volcanic islands. Journal of Geophysical Research: Earth Surface 130 (8) , e2024JF008058. 10.1029/2024jf008058

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Abstract

Plain Language Summary: When volcanic eruptions create new land, they form new coasts exposed to waves that can collapse abruptly. These coasts often consist of friable material, making them easily eroded by waves. We studied coastline changes at 12 coasts formed by historical volcanic eruptions. In the cases with observations at multiple stages, the coast retreated rapidly shortly after the eruptions, but then retreated more gradually. How they retreated with time can be well represented by an equation found earlier for a coastal volcano in the Azores, Portugal. We attribute the slowing of erosion primarily to wave energy loss on widened submarine platforms. Slowing is also potentially due to erosion, removing friable material and exposing harder, more resistant rocks. Furthermore, volcanic coasts often have steep, rising terrain landward, so when cliffs collapse, they generate larger piles of debris that further protect the cliffs. Surprisingly, erosion rates did not vary with the size of local waves or rainfall. Instead, local rock type and fracture density may dominate how quickly these young volcanic coasts erode.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/
Publisher:	American Geophysical Union
ISSN:	2169-9003
Date of First Compliant Deposit:	26 August 2025
Date of Acceptance:	16 August 2025
Last Modified:	26 Aug 2025 15:30
URI:	https://orca.cardiff.ac.uk/id/eprint/180672

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