Paleoearthquakes of the Düzce fault (North Anatolian Fault Zone): Insights for large surface faulting earthquake recurrence

Abstract

The 12 November 1999 Mw 7.1 earthquake ruptured the Düzce segment of the North Anatolian Fault Zone and produced a ∼40‐km‐long surface rupture. To improve knowledge about earthquake recurrence on this fault, we undertook paleoseismological trench investigations. We found evidence for repeated surface faulting paleoearthquakes predating the 1999 event during the past millennium. Dating was based on radiocarbon, 210Pb analyses, and archaeological considerations. In addition to the 1999 earthquake, prior surface faulting earthquakes are dated as follows: A.D. 1685–1900 (possibly end of 19th century), A.D. 1495–1700, and A.D. 685–1020 (possibly A.D. 890–1020). The A.D. 967 and A.D. 1878 historical earthquakes are good candidates to have ruptured the Düzce fault correlating with the oldest and penultimate paleoearthquakes. No obvious correlation for the third paleoearthquake (A.D. 1495–1700) exists. These results shows that the Düzce fault considerably participates, along with the parallel Mudurnu fault sections, in the seismogenic deformation taking place along this part of the North Anatolian Fault. Four events since A.D. 685–1020 (possibly A.D. 890–1020) would yield an average recurrence time for the Düzce fault of 330–430 years (possibly 330–370 years). The three most recent earthquakes, including 1999, occurred within 500 years. Merging results from other paleoseismological studies along the Düzce fault show a consistency of results and yields average recurrence times for the past 2000 years of 320–390 years. Assuming that the 1999 slip (2.7 m average, 5 m maximum) is representative of the behavior of this fault, the above recurrence times yield a reference figure of fault slip rate in the range 6.9–15.6 mm/a.

Recent behavior of the North Anatolian Fault: Insights from an integrated paleoseismological data set

“…[61] Four studies, involving multiple trench sites have been conducted in relatively close proximity on the Düzce Fault that ruptured in the 1999 Düzce earthquake [Hitchcock et al, 2003;Komut, 2005;Pantosti et al, 2008;Pucci, 2006;Sugai et al, 2001]. Sugai et al [2001] used a novel technique involving a geosclicer to constrain earthquake timing near Lake Efteni.…”

“…We generally disagree with these interpretations and do not use data from this study from further discussion. Because the other studies on the Düzce Fault [Hitchcock et al, 2003;Pantosti et al, 2008] comprise multiple trenches, at locations which overlap one another, Table S3 shows the data from each trench individually. We are unsure whether all of the dates are conventional radiocarbon ages; some are rounded while others are not.…”

“…Therefore, the results from existing paleoseismic investigations have been determined using slightly different methodologies, making it dubious to draw comparisons between them. With a long historical earthquake record [e.g., Ambraseys and Jackson, 1998], a relative abundance of paleoseismic data [e.g., Hartleb et al, 2006;Kozacı, 2008;Pantosti et al, 2008;Rockwell et al, 2009], and relatively simple fault geometry (i.e., linear without major interacting faults) along the eastern two thirds [e.g., Barka, 1992], the North Anatolian Fault (NAF) is an ideal natural laboratory to study long-term (thousands of years) patterns of seismicity.…”

Palaeolimnology of Lake Sapanca and identification of historic earthquake signals, Northern Anatolian Fault Zone (Turkey)

“…Knowledge of past earthquakes in earthquake-prone areas raises the possibility of protecting humans and infrastructure (Atakan, et al, 2002;Sørensen et al, 2006). It was for these reasons that the European Union project on "Large Earthquake Faulting and Implications for the Seismic Hazard Assessment in Europe" (RELIEF) was initiated (Pantosti et al, 2008).…”

Error propagation in time-dependent probability of occurrence for characteristic earthquakes in Italy

“…In our opinion, this is true only in theory. Worldwide practice (e.g., see Ellsworth et al 1999 for California; Shimazaki 2006 for Japan; Pantosti et al 2008 for Turkey) derives α values from observed sets of interoccurrence times, which are affected by epistemic errors due, at least, to completeness and sensitivity reasons (possible missed events and uncertainties in paleoseismic event dates). The aperiodicity α associated to a fault, or to a group of characteristic earthquake sources, should be, therefore, considered a representative of both the aleatory and epistemic variability.…”