Seismic parameters re-determined from historical seismograms of 1935-Erdek–Marmara Island and 1963-Çınarcık Earthquakes

Abstract

In this study, the original seismograms of the 1935-Erdek–Marmara Island and 1963-Çınarcık Earthquakes, recorded at local and regional distances, were vectorized. The epicentral locations have been calculated using available readings from original records and also ISS and seismic station bulletins for 04.01.1935-14:41 and 16:20 Marmara Island–Erdek Earthquakes and 18.09.1963-16:58 Çınarcık Earthquake. The epicenter determinations show that the first event in 04.01.1935 was located at 40.72N–27.72E, while the second one occurred at 40.61N–27.43E, indicating that both were located near the Marmara Island. Another finding is that the 1963 event was located at 40.80N–29.18E, near the Princes’ Island fault. Furthermore, moment tensor inversion method was applied on these earthquakes by using original seismograms, which provided an opportunity to illuminate the seismotectonic features of Marmara Region based on the retrieved fault mechanism solutions. For the first time, the fault mechanisms for 04.01.1935-14:41 and 16:20 Earthquakes were determined using moment tensor inversion from the original seismic waveforms. Likewise, the result obtained for the fault mechanism of 1963 Çınarcık Earthquake showed normal fault mechanism with much shallower depth than estimated before. Our preferred solutions showed that the fault mechanisms for the three events are normal faults and coincide with the seismotectonic structure of the Marmara Region.