Fast relocking and afterslip-seismicity evolution following the 2015 Mw 8.3 Illapel earthquake in Chile

0578048 - GFÚ 2024 RIV US eng J - Journal Article
Hormazábal, J. - Moreno, M. - Ortega-Culaciati, F. - Báez, J. C. - Peña, C. - Sippl, Christian - González-Vidal, D. - Ruiz, J. - Metzger, S. - Yoshioka, S.
Fast relocking and afterslip-seismicity evolution following the 2015 Mw 8.3 Illapel earthquake in Chile.
Scientific Reports. Roč. 13, č. 1 (2023), č. článku 19511. ISSN 2045-2322. E-ISSN 2045-2322
EU Projects: European Commission(XE) 947856 - MILESTONE
Institutional support: RVO:67985530
Keywords : Maule earthquake * subduction zone * megathrust earthquakes
OECD category: Volcanology
Impact factor: 4.6, year: 2022
Method of publishing: Open access
https://www.nature.com/articles/s41598-023-45369-9

Large subduction earthquakes induce complex postseismic deformation, primarily driven by afterslip and viscoelastic relaxation, in addition to interplate relocking processes. However, these signals are intricately intertwined, posing challenges in determining the timing and nature of relocking. Here, we use six years of continuous GNSS measurements (2015-2021) to study the spatiotemporal evolution of afterslip, seismicity and locking after the 2015 Illapel earthquake (M-w 8.3). Afterslip is inverted from postseismic displacements corrected for nonlinear viscoelastic relaxation modeled using a power-law rheology, and the distribution of locking is obtained from the linear trend of GNSS stations. Our results show that afterslip is mainly concentrated in two zones surrounding the region of largest coseismic slip. The accumulated afterslip (corresponding to M-w 7.8) exceeds 1.5 m, with aftershocks mainly occurring at the boundaries of the afterslip patches. Our results reveal that the region experiencing the largest coseismic slip undergoes rapid relocking, exhibiting the behavior of a persistent velocity weakening asperity, with no observed aftershocks or afterslip within this region during the observed period. The rapid relocking of this asperity may explain the almost regular recurrence time of earthquakes in this region, as similar events occurred in 1880 and 1943.
Permanent Link: https://hdl.handle.net/11104/0347075