Comparison of inversion results calculated from short and long-period data: An example from the Crete Island

Alkan H., Öztürk S.

8th INTERNATIONAL CONFERENCE ON MATHEMATICS “An Istanbul Meeting for World Mathematicians”, İstanbul, Türkiye, 9 - 11 Temmuz 2024, ss.295-304

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Basıldığı Şehir: İstanbul
  • Basıldığı Ülke: Türkiye
  • Sayfa Sayıları: ss.295-304
  • Van Yüzüncü Yıl Üniversitesi Adresli: Evet

Özet

In this study, we aimed to investigate the crust and upper mantle structure in the Crete Island (Eastern Mediterranean) using the algorithm called inversion of P-receiver functions. For this purpose, we chose 2 short-period and 2 long-period seismic stations named KERA and ZKR, operated by GE (GEOFON Program GFZ Potsdam, https://geofon.gfz-potsdam.de/). Also, we tried to establish a relationship among P- and S-wave velocities, epicentral and hypocentral distributions of events, and local tectonic units. To calculate the P-receiver functions, teleseismic earthquake data composed of approximately 400 events were selected. The occurrence parameters of earthquakes were epicentral distances between 30°-90° with a magnitude greater than Mw≥5.7. The time interval to collect the earthquakes was chosen from 2005 to 2023. To perform the inversion of P-receiver functions, we applied the three important steps called (i) LQT rotation, (ii) time-domain deconvolution, and (iii) stacking. Then, we performed the inversion algorithm which is exactly similar to the simulated annealing method. P-receiver functions calculated from long- and short-period data were inverted using the 0 km depth stacking to create the P- and S-wave velocity-depth models beneath the KERA and ZKR stations. According to P-wave and S-wave velocity histograms, the crust with a thickness of approximately 28 km (P-wave velocity is ~8.5 km/s and S-wave velocity is ~4.3 km/s) is underlain by the mantle lid with its bottom at a depth of ~100 km. The seismic lithosphere-asthenosphere boundary is manifested by decreasing P- and S-wave velocity changes. Also, a low Vp/Vs ratio is observed in the upper crust beneath the ZKR station. The high crustal velocities calculated as a result of the inversion and the earthquakes that occurred at crustal depths were compatible with each other and hence, this harmony showed that shallow earthquake activity will continue in the future. Finally, the crust-mantle (Moho) and Lithosphere-Asthenosphere discontinuities beneath the Crete Island are consistent with previously performed studies.