| Abstract | Rapid determination of centroid moment tensor (CMT) of earthquakes, namely the source centroid location, focal
mechanism, and magnitude is important for early disaster responses and issuing Tsunami warnings. Using
the SWIFT system (Source parameter determinations based on Waveform Inversion of Fourier Transformed seismograms)
developed by Nakano et al. (2008), we are developing earthquake monitoring system in Turkey. Also
determinations of CMT for background seismicity can resolve the stress field in the crust, which may contribute
to evaluate potential earthquake, to develop scenarios for future disastrous earthquakes, or to find hidden faults in
the crust. Using data from regional network in Turkey, we have tried a waveform inversion for an M=4.4 earthquake
that occurred about 50 km south of Sea of Marmara, of which source location is at 40.0N and 27.9E with
15 km depth (after the ANSS Comprehensive Catalog). We successfully obtained the CMT solution showing a
right-lateral strike-slip fault, of which one of the nodal planes strikes ENE-WSW, corresponding to the strike of an
active fault mapped here. This fault runs parallel to the north Anatolian fault, and large earthquakes of Ms 7.2 and
7.0 ruptured this fault on 1953 and 1964, respectively. Using the regional network data, we can determine CMT for
earthquakes as small as magnitude about 4. Of course, the lower limit of magnitude depend on the data quality. In
the research project of SATREPS – Earthquake and tsunami disaster mitigation in the Marmara region and disaster
education in Turkey, we will develop CMT determination system and CMT catalogue in Turkey. |
