Relocation of the 2018 Zakynthos, Greece, aftershock sequence: spatiotemporal analysis deciphering mechanism diversity and aftershock statistics

An M w 6.8 earthquake occurred on October 25, 2018, 35 km offshore from the southwest coastlines of Zakynthos Island. The aftershock sequence appeared remarkably productive with six aftershocks of M  ≥ 5.0 in the first month and tens of aftershocks with M  ≥ 4.0 during the study period. The GCMT sol...

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Bibliographic Details
Published in:Acta geophysica 2020-10, Vol.68 (5), p.1263-1294
Main Authors: Karakostas, V., Kostoglou, A., Chorozoglou, D., Papadimitriou, E.
Format: Article
Language:English
Subjects:
Aftershocks
Clusters
Earth and Environmental Science
Earth Sciences
Earthquakes
Geological faults
Geophysics/Geodesy
Geotechnical Engineering & Applied Earth Sciences
Relocation
Research Article - Solid Earth Sciences
Seismic activity
Seismicity
Statistical analysis
Stress transfer
Structural Geology
Subduction (geology)
Time series
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Summary:An M w 6.8 earthquake occurred on October 25, 2018, 35 km offshore from the southwest coastlines of Zakynthos Island. The aftershock sequence appeared remarkably productive with six aftershocks of M  ≥ 5.0 in the first month and tens of aftershocks with M  ≥ 4.0 during the study period. The GCMT solution for the main shock suggests a very low angle plane (dip = 24°) for a dextral strike–slip faulting (rake = 165°). A similar solution is suggested for the largest aftershock ( M w 5.9) that occurred 5 days afterward. The proximity of the main shock location with the dextral active boundary of Kefalonia Transform Fault Zone (KTFZ) along with the Hellenic Subduction front supports this oblique faulting. The aftershock activity is comprised mostly in depths 5–12 km and forms eight distinctive clusters that accommodate regional strain and evidence strain partitioning. The role of stress transfer and statistical analysis are combined for detailing the highly productive aftershock sequence. Earthquake networks analysis reveals their random structure soon after the main shock, which became small-world structure after the first 200 days. Time series analysis constructed from the aftershock frequency and seismic moment release and manifested significant correlation among the eight seismicity clusters.
ISSN:1895-6572
1895-7455
DOI:10.1007/s11600-020-00483-4