Paleoseismologic evidence for the relatively regular recurrence of infrequent, large-magnitude earthquakes on the eastern North Anatolian fault at Yaylabeli, Turkey

Abstract

Paleoseismologic trenches excavated across the eastern part of the North Anatolian fault at Yaylabeli, Turkey, provide evidence for fi ve surface ruptures during the past 2000 yr. We interpret these events as: (1) the historical 1939 M w 7.9 earthquake; (2) the historical 1254 A.D. earthquake; (3) the historical 1045 A.D. earthquake; (4) an earthquake that occurred between 660 A.D. and 1020 A.D., most probably between 717 A.D. and 844 A.D.; and (5) an earthquake that occurred between 302 A.D. and 724 A.D., possibly the historical 499 A.D. event. Although one of the interevent intervals we document is 685 yr long (between the 1254 A.D. and 1939 A.D. earthquakes), the other three intervals are between 200 and 350 yr long. Our results, which facilitate a rare opportunity to test the completeness of the paleoseismologic record at multiple sites, are generally similar to those from the nearby Çukurçimen trench site, located 2 km to the east, demonstrating reproducibility of the paleoearthquake record. However, the eighth-to ninth-century event (E4) that we document at Yaylabeli was not observed at Çukurçimen. The addition of this event facilitates the recognition of a previously unnoticed North Anatolian fault earthquake cluster, during which at least the eastern and central parts of the fault appear to have ruptured during a brief sequence in the eighth and ninth centuries. Addition of this possible cluster suggests that the North Anatolian fault commonly ruptures in brief, systemwide sequences, although the individual earthquakes in each sequence differ from cluster to cluster in terms of location, magnitude, and rupture sequence. These paleoearthquake data reinforce the idea of relatively regular recurrence of infrequent, large-magnitude earthquakes on the eastern section of the North Anatolian fault. We attribute this relatively simple behavior to the structural maturity of the North Anatolian fault and its relative isolation from other major seismic sources within the Anatolia-Eurasia plate boundary.

Are U‐Th Dates Correlated With Historical Records of Earthquakes? Constraints From Coseismic Carbonate Veins Within the North Anatolian Fault Zone

“…The peak at 1430 AD that is represented by two carbonate samples with more precise relative age errors corresponds to the most prominent event peak obtained from the carbonate dating (Figure S8 and Table ). This peak is consistent, within the range of analytical error, with the results of all paleoseismic trenching studies conducted to the east of Reşadiye (Fraser et al, ; Hartleb et al, ; Kozacı et al, ; Zabcı et al, ). The event dated in these trenches was attributed to the 1254 AD earthquake in the historical earthquake records.…”

“…Note that horizontal lines extended to the related peak on relative probability curve project our results. T1 = Fraser (), T2 = Zabcı et al (), T3 = Polat et al (), T5 = Fraser et al (), T6 = Kozacı et al (), T7 = Hartleb et al ().…”

“…Along the Mihar‐Tümekar segment three research groups have excavated several trenches (Hartleb et al, ; Kozacı et al, ; Fraser et al, ; Figure b), where 1200 BC, 499 AD, 1045 AD, and 1254 AD events were dated (Figure ). Moreover, Fraser et al () provided evidence of the 1668 earthquake in the western part of the segment (Figure ).…”

“…= Mihar‐Tumekar, E.S. = Erzincan Segments, T1 = Fraser (), T2 = Zabcı et al (),T3 = Polat et al (), T4 = Hubert‐Ferrari et al (), T5 = Fraser et al (), T6 = Kozacı et al (), T7 = Hartleb et al (). (c) Location of the Reşadiye fissure‐ridge travertine along the NAFZ.…”

Kinematic analysis and palaeoseismology of the Edremit Fault Zone: evidence for past earthquakes in the southern branch of the North Anatolian Fault Zone, Biga Peninsula, NW Turkey

“…When we considered these earthquakes' locations, formation timings and magnitudes, it seems that the large earthquakes, which eventuated on the EFZ and were quite close to the YGFZ, triggered each other. The palaeoseismological studies carried out in the northern branch of the NAFZ suggested that the estimated recurrence interval is 150-300 years for surfaceruptured large earthquakes (Hartleb, Dolan, Kozaci, Akyuz, & Seitz, 2006;Ikeda et al, 1991;Kozacı, Dolan, & Finkel, 2009;Kozacı, Dolan, Yönlü, & Hartleb, 2011;Özaksoy et al, 2010;Rockwell, Barka, Dawson, Akyuz, & Thorup, 2001;Rockwell et al, 2009), while palaeoseismological studies on the southern branch are very limited, except for Yoshioka and Kuşçu (1994), Kürçer et al (2008), Belindir (2008) and Özalp et al (2013); however, Özalp et al (2013) reported that the return period of the greater earthquakes that occurred on the southern branch was not regular, but these fault segments have the potential to produce earthquakes on the northern branch. Additionally, Belindir (2008) reported an earthquake recurrence interval on the YGFZ that ranged between 253 and 925 years.…”