| Abstract Submission No. | ABS-1.2-0036 |
| Title of Abstract | Decomposition of geocentric sea-level rise in the Maritime Continent reveals a tectonic fingerprint |
| Authors | A. G. Nidheesh*, Sophie Coulson, Brent G. Delbridge, Grace Ertel, Aurel Moise, Matthew D. Palmer |
| Organisation | Indian National Centre for Ocean Information Services (INCOIS) |
| Address | INCOIS, HYDERABAD Hyderabad, Telangana, India Pincode: 500090 E-mail: nidheesh.ag@incois.gov.in |
| Country | India |
| Presentation | Oral |
| Abstract | The islands of the Maritime Continent (MC) are highly vulnerable to sea-level rise driven by a range of barystatic, sterodynamic, and tectonic processes. Co-seismic and inter-seismic deformation can modify sea surface height (SSH) through seafloor displacement and gravitational changes associated with crustal mass redistribution, yet the long-term impacts of these processes on SSH remain poorly understood. Here we compare satellite altimetry observations of SSH over the MC (1993¿2021) with model-based estimates of the major contributors to SSH change. We predict spatio-temporal patterns of SSH change associated with glacial isostatic adjustment (GIA) and with gravitational, rotational, and deformational (GRD) effects arising from recent changes in polar ice sheets, glaciers, and terrestrial water storage. These predictions draw on contemporary reconstructions from GRACE data, glacier mass balance models, and global hydrological datasets. Sterodynamic SSH variations are estimated from ocean reanalysis products, and the associated ocean mass redistribution is used to compute ocean GRD. The combined contribution of these processes accounts for most of the observed SSH change across the MC. However, we identify an anomalous SSH trend northwest of Sumatra that is not attributable to sterodynamic or GIA/GRD processes. This rate anomaly coincides with GRACE-derived long-term geoid change near the 2004 M9.1 Indian Ocean earthquake rupture zone. We interpret this signal as the first observational evidence of gravitational perturbations to geocentric SSH induced by subduction processes. |
| Keywords | Sea-level rise, sterodynamic changes, GRD fingerprints, Subduction tectonics |