Relative sea level and coastal vertical movements in relation with volcano-tectonic processes in Mayotte

TL;DR

This study investigates the Holocene vertical movements of Mayotte Island, linking them to volcanic and mantle processes, and highlights the significant role of deep magma reservoir pressure changes and volcanic loading.

Contribution

It provides new insights into the volcanic and mantle influences on Holocene vertical movements in Mayotte, integrating geological data with modeling approaches.

Findings

An abrupt 10 m subsidence 9.3 kyr ago.

A 10 m uplift from 8.1 to 7 kyr ago at 9 mm/yr.

Deep magma reservoir pressure changes caused surface movements.

Abstract

During the last 10 kyr, significant subsidence and uplift occurred on Mayotte Island in the Comoros archipelago, but the role of volcanic processes in Holocene vertical movements has been neglected. Here, we show that an abrupt subsidence of 10 m occurred 9.3 kyr ago and then an uplift of the same amplitude occurred at a rate of 9 mm/yr from 8.1 kyr to 7 kyr ago, and we compare the relative sea level of Mayotte with a reference sea level curve. Using a modeling approach, this study shows that an increase and a decrease in pressure in a deep magma reservoir was responsible for the ~10 m subsidence and the 10 m uplift, whereas the loading by new volcanic edifices has caused the subsidence that has occurred during the past 6.1 kyr. The surface movement was caused by pulses from the deep mantle that were probably related to superplume activity.