THE 16 APRIL 2015 MW6.1 EARTHQUAKE SEQUENCE NEAR KASOS ISLAND AT THE EASTERN HELLENIC SUBDUCTION ZONE

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Published: Jul 27, 2016
DOI: https://doi.org/10.12681/bgsg.11822
Keywords:
earthquake slip model focal mechanism Hellenic trench
A.A. Kiratzi
Aristotle University of Thessaloniki, Department of Geophysics
Abstract

Broad band seismic waveforms are used to determine the source model of the 16 April 2015 (UTC 18:07:44) earthquake, Mw6.1, which occurred 14 km SW of Kasos Island, in the eastern Hellenic subduction zone. The mainshock is connected with oblique leftlateral motion on a reverse fault, dipping to SE. Most of the aftershocks are compatible with strike-slip or oblique normal faulting, with the T-axes showing along arc extension. A finite fault slip inversion was performed, allowing for the rake angle to vary across the fault, to capture the variation in the slip vectors. The rupture initiated in the lower crust, at a centroid depth of 23 km, and propagated mainly towards SW. The slip is confined in depth within ~17km and 27km, mainly in a single asperity, with the peak slip of the order of 60 cm. The slip model provided synthetic seismograms which matched satisfactory the observed, and with forward modelling the ShakeMap was calculated. The 2015 Kasos earthquake sequence is compatible with shear motions parallel to the strike of the subduction zone. It provides evidence that part of the deformation in the eastern Hellenic subduction is taken up by the simultaneous operation of reverse faulting and of minor strike-slip and oblique normal faulting, with slip vectors aligned ~ parallel to the Pliny and Strabo Trenches and the long axis of the local bathymetry.

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  • Geophysics and Seismology
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