Source and Rupture Process of the 2017 Bodrum - Kos Earthquake Inferred from Strong Ground Motion Records,


Irmak T. S. , Alçık H., Pınar A.

VI. International Earthquake Symposium, Kocaeli, Kocaeli, Türkiye, 25 - 27 Eylül 2019, ss.894-897

  • Basıldığı Şehir: Kocaeli
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.894-897

Özet

We studied the source and rupture process of the July 20, 2017 Bodrum-Kos Earthquake

(Mw=6.7) to investigate and better understand the source process and coseismic slip distribution.

Strong ground motion data with three component were collected from Kandilli Observatory and

Earthquake Research Institute, Disaster and Emergency Management Authority and Institute of

Geodynamics Strong Motion Network of Greece selecting 13 stations with 35 components. The

mainshock records were inverted to displacement to retrieve source parameters for the

mainshock through searching for the best CMT location on a 3-D grid scheme. The results

indicate that the best CMT point is located at 6 km depth and shows predominantly normal

faulting mechanism with a considerable strike-slip component; where left-lateral strike-slip

motion has been derived on the nodal planes striking NW-SE and dipping NE, while the sense of

motion is right-lateral-strike-slip on the plane extending NE-SW and dipping SW. The near-field

source modeling of the strong motion data suggests that the main moment release is located

around 4 km of the west of the initial break point and the maximum slip is 1 m, if the shear

modulus is assumed to be 30 GPa. The size of the asperity is about 40 km in length and 20 km in

width, and the duration of rupture is about 13 seconds with Mw = 6.7. The derived average stress

drop of #σ=1.8 MPa. The average displacement is calculated as 0.68 m. Slip distribution shows

a large asperity at shallower part of the fault plane at the eastern side of the hypocenter. The

rupture is very smooth and gradually expands near the hypocenter and propagates bilaterally in

the directions east and west (but mostly to the east). The distribution of the slip vectors indicates

that a normal fault mechanism is dominant during the whole rupture propagation. However, a

small right lateral strike-slip component can be seen at the larger moment release area where

located - W of the hypocenter. The moment release and displacements rates in the shallower

parts of the fault plane are larger than the deeper parts of the fault plane. This could increase the

chances of a continuous surface rupture that could be responsible for tsunami generation.