GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.3 - POSTER GNGTS 2023 REAR: a Regional ElAstic Rebound calculator A. Consorzi 1 , D. Melini 2 , G. Spada 1 , P. Gegout 3 1 Dipartimento di Fisica e Astronomia (DIFA), Settore Geofisica, Alma Mater Studiorum – Università di Bologna, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione di Sismologia e Tettonofisica, Roma 3 Observatoire Midi-Pyrenees, Toulouse, France Mass redistribution on the Earth’s surface causes displacements and gravity field anomalies on various temporal scales. REAR (the Regional ElAstic Rebound calculator) is a Fortran 90 program for modeling the instantaneous response to surface loads of a spherical, non-rotating, perfectly elastic and isotropic Earth. Surface loads can be either associated to redistributions of ice and water at the Earth’s surface. The solution of the Elastic Rebound (ER) problem is of particular interest in regions currently subject to deglaciation in response to climate change but it is also relevant in other contexts in the realm of solid Earth geophysics. REAR allows for the high-resolution computation of relevant geodetic variables using the classical solution of the surface loading problem (Farrell, 1972). REAR only accounts for the deformation induced by a surface load ( e.g. , a cryospheric load), and does not solve the Sea Level Equation (Farrell and Clark, 1976); therefore, REAR is appropriate for regional problems in which the self-gravitation of the oceans and the effects of Earth rotation can be neglected. REAR is particularly oriented to the computation of geodetic variables (horizontal and vertical displacement, geoid height variations) that can be observed in the periphery of glaciers or ice sheets currently subject to significant mass variations in consequence of global warming (e.g., Spada et al., 2012). The speed and ease of use of REAR make it the ideal tool for a vast range of geo-scientifical applications, and an advanced teaching support for quantitative geodynamics topics. In REAR, the surface load distribution is modelled as a bed of disk-shaped elements of constant radius. The axial symmetry of the discs ensures the direct application of standard formulas for the response functions (Farrell, 1972). The user can prescribe either the disk thickness variation or the rate of change of the thickness. In the first case, the outputs of REAR represent the instantaneous displacements in response to loading; in the second one, they represent a rate of displacement (geodetic rates) assuming a constant rate of melting or accretion. Moreover, REAR can be configured to deal with compensated or uncompensated surface loads: when the load is compensated, the disc load extra mass is exactly balanced by the mass of a complementary load of uniform thickness to ensure no net variation in the Earth system mass; on