Response of the solid Earth to ice mass changes: numerical modeling techniques, implementation of faults, and implications for future seismic potential in regions undergoing ice loss
Abstract
Ice sheets and glaciers are extremely sensitive to climate changes such as those that have occurred during the Quaternary glacial-interglacial cycles. From the point of view of the solid Earth, ice bodies represent surface loads that vary through space and time. These mass fluctuations cause transient stresses in the Earth's crust, which are superimposed on the tectonic stress field. As the crust is usually close to brittle failure, even small stress changes may trigger faulting. On the timescale of a glacial-interglacial cycle, ice mass redistributions can cause stress changes that are sufficiently large to promote or suppress faulting. Here we present an evaluation of finite-element modeling techniques based on the software ABAQUS, which have been used to simulate solid Earth deformation in response to ice sheet growth and melting (Hampel et al., CAGEO, 2019). Benchmark models for glacial isostatic adjustment (GIA) show that ABAQUS models applying the geometrically non-linear formulation (NLGEOM) yield correct isostatic restoring forces, displacements and stresses for incompressible and compressible materials. Models with NLGEOM also enable the implementation of faults as frictional contact interfaces, which allows quantifying their response to ice mass fluctuations in terms of amount and rate of fault slip. The model results show - In agreement with paleoseismological data - that many faults worldwide experienced a pronounced slip rate increase in response to post-LGM ice sheet melting and lithospheric rebound. The currently low level of seismicity in Greenland and Antarctica can be explained by the stresses induced by the modern ice caps, however, future ice loss may trigger intermediate to large magnitude earthquakes if the crust underneath the ice caps contains faults prone to failure. The identification of potentially seismogenic faults, for example by monitoring the microseismicity, will be essential to evaluate seismic hazard in regions undergoing ice loss.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP31C1653H
- Keywords:
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- 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions;
- GEODESY AND GRAVITY;
- 1621 Cryospheric change;
- GLOBAL CHANGE;
- 1641 Sea level change;
- GLOBAL CHANGE