The main aim of this study is to investigate the self-relation and self-similarity of earthquakes in and around the Marmara Sea (NW Turkey) by using these obtained source parameters. With this purpose, spectral source parameters for 77 small to moderate earthquake (3.5 ≤ M_L ≤ 5.2) that occurred during 2004–2018 have been determined from P and S wave spectra according to Brune’s source model by using regional broadband seismograms. The average ratio of P/S wave corner frequency is found to be 1.3 that suggesting higher corner frequency for P wave. The static stress drops range from 0.1 and 136 MPa with a median value of 9.8 MPa (98 bars). The high stress drops for these events can indicate high frictional strength and low strain-rate of the faults. Similarly, the low values of the stress drop can indicate a general weakness of the faults in the study area. There is no clear dependence between the seismic moment and the static stress drop in the analyzed events but some events which have lower seismic moment value also have lower stress drop. Obtaining results indicated the corner frequency decreases with increasing of the seismic moment. Also, a slight depth dependence of the corner frequency has been observed for the analyzed events. Shallower events have larger corner frequency value than deeper events. Also, a clear depth dependence of the stress drop values has not been observed. However, the depth dependence of the seismic moment is seen more clearly. Our results indicated that the deeper events have larger seismic moment values in the study area. In spite of scattering in small events, a linear relationship between local magnitude (M_L) and moment magnitude (M_W) could be obtained as M_W = 1.4261(± 0.31) + 0.6399(± 0.08)M_L from P waves spectra and M_W = 0.0136(± 0.21) + 0.9883(± 0.05)M_L from S wave spectra and calculated M_W values are consistent with waveform inversion (centroid moment tensor — CMT) results. These relationships may be useful for seismic hazard studies in the study area.

中文翻译：

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马尔马拉地区（土耳其）中小地震的震源参数

这项研究的主要目的是使用获得的震源参数研究马尔马拉海（土耳其西北）及其周围地区地震的自相关性和相似性。与此目的，光谱源参数为77小到中等地震（3.5≤中号_大号根据Brune的震源模型，使用区域宽带地震图根据P和S波谱确定了2004-2018年发生的≤5.2）。发现P / S波拐角频率的平均比率为1.3，表明P波的拐角频率更高。静应力下降范围为0.1到136 MPa，中值为9.8 MPa（98巴）。这些事件的高应力下降可能表明断层具有较高的摩擦强度和较低的应变率。同样，应力降的低值可能表明研究区域的断层普遍脆弱。在所分析的事件中，地震矩与静应力下降之间没有明显的依存关系，但是某些地震矩值较低的事件也具有较低的应力下降。结果表明，转角频率随地震力矩的增加而减小。此外，对于所分析的事件，还观察到拐角频率的轻微深度依赖性。较浅的事件比较深的事件具有更大的转折频率值。而且，还没有观察到应力降值的明显的深度依赖性。但是，可以更清楚地看到地震矩的深度依赖性。我们的结果表明，较深的事件在研究区域具有较大的地震矩值。尽管在小事件中会发生散射，但局部幅度（尚未发现应力下降值的明显的深度依赖性。但是，可以更清楚地看到地震矩的深度依赖性。我们的结果表明，较深的事件在研究区域具有较大的地震矩值。尽管在小事件中会发生散射，但局部幅度（尚未发现应力下降值的明显的深度依赖性。但是，可以更清楚地看到地震矩的深度依赖性。我们的结果表明，较深的事件在研究区域具有较大的地震矩值。尽管在小事件中会发生散射，但局部幅度（M _L）和力矩大小（M _W）可通过P波谱获得M _W = 1.4261（±0.31）+ 0.6399（±0.08）M _L且M _W = 0.0136（±0.21）+ 0.9883（±0.05）M来自S波谱的_L和计算出的M _W值与波形反演（质心矩张量— CMT）结果一致。这些关系对于研究区域的地震灾害研究可能有用。