SCEC2024 Poster #016: Abundant Repeating Earthquakes with Non-repeatable Ruptures on the Erkenek-Pütürge Fault (SE Turkey)

Group B, Poster #016, Seismology

Abundant Repeating Earthquakes with Non-repeatable Ruptures on the Erkenek-Pütürge Fault (SE Turkey)

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Poster Presentation

2024 SCEC Annual Meeting, Poster #016, SCEC Contribution #13645 VIEW PDF

Repeaters are known as earthquakes that rupture the same asperity repeatedly, generating highly-similar waveforms. However, repeaters can also experience various rupture processes, especially following large earthquakes, as evidenced by the temporal changes of source parameters. In this study, we developed a new strategy to systematically detect the repeaters that show non-repeatable ruptures, i.e. non-repeaters. Our workflow starts from detecting typical repeater sequences with waveform cross-correlation (CC) above 0.9 and CC-measured differential S-P time within 0.01 s. Based on this, we adopt a much lower CC threshold to see whether non-repeaters are contained within each repeater sequenc...e, which classify them as simple sequences or complex sequences. We apply this workflow to the Erkenek-Pütürge fault (EPF) of SE Turkey, and detected 41 repeater sequences during 2020-2023/04, which covers the post-seismic period for both the 2020 Mw 6.8 and 2023 Mw 7.8 earthquake that struck this fault segment. These repeaters distribute in the vicinity of the ruptured area at a depth ranging from 0-15 km, indicating persistent creep and afterslip occurring in these patches. Intriguingly, 28 out of the 41 repeater sequences (~68%) are complex, containing one or more non-repeaters. We further explore the relationship between magnitude and recurrence interval. Results show that ~74% repeater sequences have their first 2 events following the mainshock showing decreasing magnitude, whereas only 30% of the pre-M7.8 repeaters show monotonic magnitude decreasing over the ~3 years. This imply that repeater magnitudes are less sensitive to fault slip under a low rate. However, among the 19 sequences that show slip rate modulation on magnitude, 15 of them (79%) are complex, suggesting that inner complexity is probably one of the necessary conditions for such modulation.
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