Relocation of recent seismicity and seismotectonic properties in the Gulf of Corinth (Greece). Issue 2 (14th October 2017)

• Record Type: Journal Article
• Authors: Mesimeri, Maria; Karakostas, Vassilios; Papadimitriou, Eleftheria; Tsaklidis, George; Jacobs, Katrina
• Is Part Of: Geophysical journal international. Volume 212:Issue 2(2018:Feb.)
• Page Start: 1123
• Page End: 1142
• Publication Date: 2017-10-14
• Subjects: Waveform inversion -- Seismicity and tectonics -- Continental tectonics: extensional -- Dynamics: seismotectonics; Geophysics -- Periodicals; 550
• DOI: 10.1093/gji/ggx450
• Languages: English
• ISSNs: 0956-540X

Abstract

Summary: Recent seismicity (2008–2014) taking place in the Gulf of Corinth and recorded, since the establishment of the Hellenic Unified Seismological Network is relocated in this study. All the available P and S manually picked phases along with the waveforms of 55 broad-band, three-component seismological stations were used. The relocation is performed using the double difference method with differential times derived from phase-picked data and waveform cross-correlation. The accuracy of the relocated catalogue, estimated using a bootstrap approach, is of the order of few hundred metres. In an attempt to define the stress regime in the area, we compute moment tensors of 72 earthquakes with M L ≥ 3.0 and use them to calculate the total seismic moment tensor. A dominant strike of 270° that found in the westernmost part, was changed to 270°–290° at the centre of the gulf, perpendicular to the almost N–S extension of the rift. Further to the east, a gradual change in fault orientation is observed. In the easternmost part, the strike becomes 240°, in agreement with the geometry of the rift. The highly accurate earthquake catalogue, consisting of ∼26 000 events, reveals two patterns of activity in the western Corinth Gulf, namely, strongly clustered seismicity in both space and time in shallow depths and below that activity a very narrow shallow north-dipping seismic zone. Earthquake clusters, mainly located in the western study area, are identified using CURATE algorithm and associated with different north or south-dipping fault segments. The seismicity in the shallow north-dipping seismic zone, defined in detail in this study, is continuous and free of earthquake clusters. This continuous activity most probably defines the boundaries between brittle and ductile layers. The central and eastern parts of the study area mainly accommodate spatiotemporal clusters.