Seismicity of the 2017 north Aegean Sea earthquake sequence
Abstract
Ayvacık district of Çanakkale province was hit by a moderate size (Mw=5.2) earthquake on 6 February 2017. Centroid moment tensor solutions for 60 events with moment magnitudes (Mw) between 3.4 and 5.3 are computed by applying a waveform inversion method on data from the Turkish and Greek broadband seismic networks. The data covers the period between 1 January and 28 February 2017. The mainshock is a shallow focus normal event with strike-slip component at a depth of 10 km. Focal depths of aftershocks range from 3 to 24 km. The seismic moment (Mo) of the mainshock is estimated as 7.62 × 1016 Nm. The calculated rupture duration of the Ayvacık mainshock is 3 s. The focal mechanisms of the aftershocks are mainly normal faulting with a minor strike-slip component. The geometry of focal mechanisms reveals a normal faulting regime with NE-SW trending direction of T-axis in the entire activated region. The stress tensor inversion results indicate a predominant normal stress regime with a WNW-ESE oriented maximum horizontal compressive stress (SH). In the development of the Biga Peninsula in NW Anatolia is in good agreement with the resolved stress tensors. With respect the newly determined focal mechanisms, the effect of the propagating of the North Anatolian Fault into Aegean Sea is very clearly pronounced. According to high-resolution hypocenter relocation of the 2017 Ayvacık seismic sequence, five main clusters are revealed. The aftershock activity in the observation period between 1 January and 28 February 2017 extends from the mainshock cluster from W to E direction. Seismic cross-sections indicate that a complex pattern of the hypocenter distribution with the activation of ten segments. The western cluster is associated with a fault plane trending mainly N-S and dipping vertical, while the eastern is related to a fault plane trending NE-SW and dipping towards SW. The best constrained focal depths indicate that the aftershock sequence is mainly confined in the crust (depth ≤ 24 km) and is operating in the approximate depth range from 3 to 24 km. Consequently, Coulomb stress analysis is performed to calculate the stress transfer and correlate it with the activated region. Positive lobes with stress more than 3 bars are obtained, indicating that these values are large enough to increase the Coulomb stress failure towards NW-SE direction.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.T13I0339G
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGYDE: 8110 Continental tectonics: general;
- TECTONOPHYSICSDE: 8118 Dynamics and mechanics of faulting;
- TECTONOPHYSICS