Refining micro-seismic catalogs around Seydişehir, Turkey

Abstract

In Turkey, two official seismology centers, Bogazici University Kandilli Observatory and Earthquake Research Institute Regional Earthquake-Tsunami Monitoring Center (KOERI-RETMC) and Republic of Turkey Prime Ministry Disaster Emergency Management Authority (AFAD) announce and share seismic catalogs with the public and international services. According to their seismic network distribution, together with different crustal models and calculation algorithms, obtaining earthquake parameters (location, depth, etc.) could differ between these two centers, especially, affecting source types of the low-magnitude events. Both low-magnitude tectonic events and artificial quakes that originating from open-pit quarry are catalogued by the seismology centers. These two centers announce different source types for the seismic events; therefore, this study focuses on the reliable identification of the micro-seismic events. Magnitude Ml<2.4 177 seismic events commonly identified in KOERI-RETMC and AFAD catalogs are used. Due to the differences between KOERI-RETMC and AFAD seismic catalogs, the “first determination” (FD) was needed to start the discrimination analyses. Then, waveforms of the station SEYD and SEDI are operated by KOERI-RETMC and AFAD were analyzed with four methods (Amplitude Ratio, Complexity, Short Time Fourier Transform and Corner Frequency-Power Spectrum) and two statistical approaches (linear and quadratic discriminant functions) with the use and comparison with FD. Finally, station-based weightings are obtained with all techniques, and the source types of all events are calculated in percent. Generally, the success rates of the methods are calculated over 90%. The reliability increases with the co-usage of many analyses and the application of method-based weighting. Hence, many methods should be used to reliably determine the source types of micro-seismic events. Both centers should make more detailed analyses to identify micro-seismic events and share their reliable and revised catalogs.