The earthquake sequence of the Gulf of Kerameikos East of Kos Island August 02 -09, 2004: First results

Introduction

On August 2, 2004 a sequence of moderate magnitude earthquakes occurred in the Gulf of Kerameikos  area (East of Kos Island) Turkey (Gokova Korfezi). The main shock took place on August 4, 2004, 03:01 GMT and it was located about 40km East of the city of Kos at 20km focal depth and  with magnitude Mw=5.5 (HRV). It is interesting to note that the sequence started on August 2, 2004, 20:29 GMT with an earthquake of magnitude ML=3.6 on the Richter scale and was followed by several events as they can be observed on the records of the nearest to the area seismic stations of  the National Observatory of Athens Seismic Network  at Samos (SMG) [02/08, 03/08, 04/08, 05/08, 06/08] and Archaggelos (ARG) [02/08, 03/08, 04/08, 05/08, 06/08]. The largest aftershocks occurred on August 4, 2004, at 04:19 GMT and 14:18 GMT with magnitudes of Mw 4.8 and 5.0 respectively (See also at http://bbnet.gein.noa.gr).

Moment Tensor Inversion First Results

The strongest events of the sequence were well recorded at all digital broad band stations operated by the Institute of Geodynamics of the National Observatory of Athens.  Moment tensor inversion using three component broad band data from the nearest available NOA stations (also GEOFON and MEDNET operating stations in the Aegean area and collaborating with NOA) (after Dreger 2002) resulted in normal fault mechanisms with the following solutions:

Preliminary Conclusions

A synthesis of the above mentioned results and a comparison with the estimations of other International Institutes, show that the earthquake sequence occurred on a fault zone of almost E-W strike. This zone starts West of Kos Island and follows the coast of  Bodrum Peninsula.

References

Dreger, D. S., 2002. Time-Domain Moment Tensor INVerse Code (TDMT_INVC) Version 1.1. User's Manual.

Compiled by Efthimios Sokos, Nicos S. Melis, George N. Stavrakakis and Costas Boukouras.