Preprints
https://doi.org/10.5194/nhess-2021-183
https://doi.org/10.5194/nhess-2021-183

  28 Jun 2021

28 Jun 2021

Review status: this preprint is currently under review for the journal NHESS.

Characterisation of fault plane and coseismic slip for the May 2, 2020, Mw 6.6 Cretan Passage earthquake from tide-gauge tsunami data and moment tensor solutions

Enrico Baglione1,2, Stefano Lorito2, Alessio Piatanesi2, Fabrizio Romano2, Roberto Basili2, Beatriz Brizuela2, Roberto Tonini2, Manuela Volpe2, Hafize Basak Bayraktar3,2, and Alessandro Amato2 Enrico Baglione et al.
  • 1Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS)- Sgonico (TS) – Italy
  • 2Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Roma 1, Via di Vigna Murata 605, 00143, Roma, Italy
  • 3Department of Physics “Ettore Pancini”, University of Naples Federico II, Naples, 80126, Italy

Abstract. We present a source solution for the tsunami generated by the Mw 6.6 earthquake that occurred on May 2, 2020, about 807thinsp;km offshore south of Crete, in the Cretan Passage, on the shallow portion of the Hellenic Arc Subduction Zone (HASZ). The tide-gauges recorded this local tsunami on the southern coast of Crete island and Kasos island. We used these tsunami observations to constrain the geometry and orientation of the causative fault, the rupture mechanism and the slip amount. We first modelled an ensemble of synthetic tsunami waveforms at the tide-gauge locations, produced for a range of earthquake parameter values as constrained by some of the available moment tensor solutions. We allow for both a splay and a back-thrust fault, corresponding to the two nodal planes of the moment tensor solution. We then measured the misfit between the synthetic and the observed marigrams for each source parameter set. Our results identify the shallow steeply-dipping back-thrust fault as the one producing the lowest misfit to the tsunami data. However, a rupture on a lower angle fault, possibly a splay fault, with a sinistral component due to the oblique convergence on this segment of the HASZ, cannot be completely ruled out. This earthquake reminds us that the uncertainty regarding potential earthquake mechanisms at a specific location remains quite significant. In this case, for example, it is not possible to anticipate if the next event will be one occurring on the subduction interface, on a splay fault, or on a back-thrust which seems the most likely for the event under investigation. This circumstance bears important consequences because back-thrust and splay faults might enhance the tsunamigenic potential with respect to the subduction interface due to their steeper dip. Then, these results are relevant for tsunami forecasting both in the framework of the long-term hazard assessment and of the early warning systems.

Enrico Baglione et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on nhess-2021-183', Anonymous Referee #1, 23 Jul 2021
  • RC2: 'Comment on nhess-2021-183', Gerasimos Papadopoulos, 05 Aug 2021

Enrico Baglione et al.

Enrico Baglione et al.

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Short summary
We investigated the seismic fault structure and the rupture characteristics of the Mw 6.6, May 2, 2020, Cretan Passage earthquake through tsunami data inverse modelling. Our results suggest a shallow crustal event with a reverse mechanism within the accretionary wedge rather than on the Hellenic Arc subduction interface. The study identifies two possible ruptures: a steeply sloping reverse splay fault and a back-thrust rupture dipping south, with a more prominent dip angle.
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