Holocene sea level changes in Southeast Asia

点击翻译按钮获取中文摘要

Changes in relative sea level (RSL) are the net effect of contributions from eustatic, isostatic, tectonic and other local factors, such as subsidence due to sediment compaction. Holocene sea-level reconstructions are needed to constrain both vertical land movements and geophysical models of Glacial Isostatic Adjustment (GIA), that are in turn used to correct sea level measurements obtained with instrumental measures, such as tide gauges. Therefore, regional Holocene RSL datasets, surveyed following standardized protocols, represent a long-term baseline against which to assess changes in sea level during the past century and to evaluate sea-level changes in the 21st century at local and regional scale. While accurate Holocene RSL datasets are available for some areas, RSL reconstructions for a region highly vulnerable to future sea level rise such as Southeast Asia are still limited, fragmentary and there are still problems associated with the correct interpretation of sea-level indicators and their relationship to sea level, and with the quality of age determinations. The overarching question of this proposal is: how can we improve our knowledge of relative Holocene sea level changes and associated processes in Southeast Asia? We will target this question re-analyzing published sea level datasets, which will be compiled in a database following a standardized approach. We will then expand our preliminary dataset, investigating several islands of the Spermonde Archipelago, which is an area that is highly sensitive to future sea level rise. Then, we will create a large set of earth models focusing on Southeast Asia, in order to have a full representation of the possible GIA effects in this area, including uncertainties due to the selected ice model and mantle viscosity profile, and use both our database and field data to refine the range of models that matches more closely geologic data. Our field data will be then analyzed using a Bayesian statistical approach in order to identify patterns of Late Holocene sea level changes. This information will be cross-analyzed with data from satellite imagery, which will be used to detect the level of human occupation of the different islands composing the Spermonde Archipelago and the land use patterns. This project, also thanks to the cooperation with the international partners that are world leaders in sea level science, will train a PhD student in all the aspects of sea level research, from laboratory and field techniques to earth modelling and data analysis.