TY - JOUR
T1 - Slip history of the 1944 Bolu-Gerede earthquake rupture along the North Anatolian fault system
T2 - Implications for recurrence behavior of multisegment earthquakes
AU - Kondo, Hisao
AU - Özaksoy, Volkan
AU - Yildirim, Cengiz
PY - 2010/4/1
Y1 - 2010/4/1
N2 - Recent research shows that active fault systems produce multisegment earthquakes; however, we have yet to understand the faulting behavior of various spatial patterns of segments. We conducted a three-dimensional trenching survey to reconstruct the detailed slip history of a fault segment that ruptured as one of the multisegment ruptures along the North Anatolian fault system. The trench site, on the Gerede segment, recorded a maximum right-lateral slip of up to 6 m that was associated with the 1944 Bolu-Gerede earthquake (M 7.4). Fault exposures show evidence of four paleoearthquakes. Radiocarbon dates, a refined probability density distribution, and correlation with historical earthquakes place the mean repeat time at ∼330 years. Four discrete paleoslips yield a slip per event of 5.0 ± 0.8 m with a coefficient of variation of 0.2. Our research suggests that multisegment earthquakes exhibit various spatial patterns, regardless of recurrence with quasiperiodicity and characteristic slip. Coincidentally, the fault geometry exhibits extremely linear traces, suggesting simple stress accumulation and release through earthquake cycles. Furthermore, the 1944 event did not occur in a single segment, and the Gerede segment probably ruptured within a slip-pulse-like rupture during a multisegment earthquake. A comparable geological slip rate of ?17 mm a-1 based on a GPS-based strain rate supports the persistence of macroscopic asperity through recent geological time. Therefore we conclude that a segment with simple fault geometry along a strike-slip fault system plays an important role in forecasting the timing of future multisegment earthquakes, but the spatial extent of such earthquakes needs to be explored further.
AB - Recent research shows that active fault systems produce multisegment earthquakes; however, we have yet to understand the faulting behavior of various spatial patterns of segments. We conducted a three-dimensional trenching survey to reconstruct the detailed slip history of a fault segment that ruptured as one of the multisegment ruptures along the North Anatolian fault system. The trench site, on the Gerede segment, recorded a maximum right-lateral slip of up to 6 m that was associated with the 1944 Bolu-Gerede earthquake (M 7.4). Fault exposures show evidence of four paleoearthquakes. Radiocarbon dates, a refined probability density distribution, and correlation with historical earthquakes place the mean repeat time at ∼330 years. Four discrete paleoslips yield a slip per event of 5.0 ± 0.8 m with a coefficient of variation of 0.2. Our research suggests that multisegment earthquakes exhibit various spatial patterns, regardless of recurrence with quasiperiodicity and characteristic slip. Coincidentally, the fault geometry exhibits extremely linear traces, suggesting simple stress accumulation and release through earthquake cycles. Furthermore, the 1944 event did not occur in a single segment, and the Gerede segment probably ruptured within a slip-pulse-like rupture during a multisegment earthquake. A comparable geological slip rate of ?17 mm a-1 based on a GPS-based strain rate supports the persistence of macroscopic asperity through recent geological time. Therefore we conclude that a segment with simple fault geometry along a strike-slip fault system plays an important role in forecasting the timing of future multisegment earthquakes, but the spatial extent of such earthquakes needs to be explored further.
UR - http://www.scopus.com/inward/record.url?scp=79959836682&partnerID=8YFLogxK
U2 - 10.1029/2009JB006413
DO - 10.1029/2009JB006413
M3 - Article
AN - SCOPUS:79959836682
SN - 2169-9313
VL - 115
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 4
M1 - B04316
ER -