Resolving coseismic and aseismic normal fault slip behaviors from InSAR time series of the European Ground Motion Service (egms)
Author(s)
Wood, James
Whittaker, Alex
Bell, Rebecca
Coveney, Saoirse
Kranis, Haralambos
Type
Journal Article
Abstract
Normal fault slip is regularly quantified for instantaneous seismic events and across geological timescales in rate-and-state friction frameworks. However, recent studies have shown that normal faults may undergo transient aseismic slip exceeding time-averaged rates, outside of steady state conditions. This highlights the need for further detailed observation of both coseismic and aseismic deformation on normal faults to better constrain how structures accommodate and release strain across all seismic stages. Here, we exploit open-source, InSAR-derived vertical ground motion data from the European Ground Motion Service (EGMS) to evaluate sub-mm scale deformation across active faults in the Larissa Basin, where two Mw > 6 earthquakes occurred in 2021, and the North Gulf of Evia, Central Greece. We resolve the spatial and temporal evolution of uplift and subsidence fields of the Larissa earthquake sequence, finding elevated coseismic uplift to subsidence ratios of 1:6–9. EGMS time series across the Costal Fault System of the North Gulf of Evia imply normal fault slip at above-creep throw rates of 2–3 mm/yr with limited associated seismicity. The nearby seismogenic Atalanti Fault shows no differential ground motion across its plane and is in an apparent locked state. Observed variable slip behaviors imply that long-term, geologically derived throw rates may combine transient periods of elevated aseismic slip, coseismic slip, and steady state motion. We consider these findings in the context of seismic hazard while assessing the applicability of EGMS data in tectonic studies to bridge an important gap in resolving fault motion across all spatial and temporal scales.
Date Issued
2025-09-01
Date Acceptance
2025-08-26
Citation
Tectonics, 2025, 44 (9)
ISSN
0278-7407
Publisher
Wiley
Journal / Book Title
Tectonics
Volume
44
Issue
9
Copyright Statement
© 2025. The Author(s). This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
License URL
Publication Status
Published
Article Number
e2025TC008904
Date Publish Online
2025-09-08