Active sediment generation on coral reef flats contributes to recent reef island expansion

Abstract

The ongoing development of Jeh Island in the Marshall Islands was investigated using aerial photographs, high-resolution satellite imagery, and radiometric dating of island sediments. Remote sensing observations show the present-day island of Jeh is the product of two or more smaller islands merging together between 1943 and 2006 which are continuing to expand despite local sea-level rise (SLR). Remote sensing observations show modern island development involving a complex multistage merging of smaller islands on a linear atoll rim. Radiometric ages of sediments demonstrate that island development is occurring through the active generation and delivery of modern sediments. Results highlight that at sites where sediment production regimes are in a healthy state, island building under conditions of SLR is possible. The findings have implications for interpreting island evolution from morphostratigraphic studies and understanding future island behavior with further SLR. ©2020 American Geophysical Union