Development of paleoseismic trench logging and dating techniques: a case study on the Central North Anatolian Fault

Fraser, Jeff
Pigati, Jeff
Hubert-ferrari, Aurelia
Vanneste, Kris
Boes, Xavier
Avşar, Ulaş
Altınok, Sevgi
The North Anatolian Fault (NAF) is a dextral strike slip fault zone extending ∼1400km in an arc across northern Turkey. This study seeks to further constrain the timing of ground rupturing earthquakes of the NAF while developing the techniques used in paleoseismology. A paleoseismic trench was opened ∼2.7km NW of Destek on a segment which ruptured (for ∼280km) in the 1943 Tosya Earthquake (Mw:7.7). The trench site comprises a pop-up structure formed by a small releasing step-over at a restraining bend which has caused progressive growth of an upslope facing scarp. The trench is situated across the main fault trace and a trapped sedimentary sequence that includes several paleosoils. The stratigraphy is expected to be Late Holocene and historic in age due to the high level of activity on the NAF, although this has yet to be confirmed by radiometric dating. Preliminary interpretation of the trench stratigraphy indicates a record of up to 6 paleoearthquake events, the presence of an angular unconformity suggests the record may be incomplete beyond the 3 most recent events on this strand. Subtle contrasts in stratigraphy made conventional face logging difficult and was therefore augmented by mapping the magnetic susceptibility (MS) of the west wall. Approximately 6000 measurements were made using a Bartington MS2 Magnetic Susceptibility Meter with a MS2E (point) Sensor with a 5cm vertical spacing and a 20cm horizontal spacing predominantly on one side of the trench. A pilot test led to development of a strategy of moving the sensor to the nearest exposure of coarse sand or finer grained material where possible to minimize the noise generated by individual clasts. To negate the sensitivity of the MS logging method to variations in temperature the survey was conducted at night. Plotted data clearly shows the contact between rock units, the rock-soil interface (reflecting fault juxtaposition), anthropogenic influence and some soil stratigraphy. Other paleoseismic investigations on this section of the NAF (Hartleb R. et al 2003 and Yoshioka T. et al 2000) have encountered out-of-stratigraphic-order ranges in 14C ages. They attributed this to reworking, in addition to which the effects of long term human occupation are likely to be similar. The trench yielded a large amount of datable material including 158 charcoal and 140 minute gastropod samples, and some ceramic, bone and slag samples. Unlike charcoal and bone fragments, fragile minute gastropods are unlikely to have been transported, reworked or used by humans, ultimately providing improved accuracy of temporal constraints on paleoearthquakes. Using both charcoal and gastropod samples, the trench chronology can be established and the use of minute gastropods for dating paleoearthquakes can be critiqued.
European Geosciences Union - General Assembly (15-20 Nisan 2007)


Defining additional stratigraphy in paleoseismic trenches by 2d logging of magnetic susceptibility :A paleoseismic investigation near lake Ladik, North Anatolian fault, Turkey
Fraser, Jeff; Hubert-ferrari, Aurelia; Vanneste, Kris; Avşar, Ulaş; Altınok, Sevgi (null; 2008-12-19)
The North Anatolian Fault (NAF) is a dextral strike-slip plate-boundary fault zone extending ~1400 km in an arc across northern Turkey. We opened a paleoseismic trench ~2.7 km NW of Destek village on a segment which ruptured (for ~280 km) in the 1943 Ladik Earthquake (Mw:7.7). Sediments exposed in the trench yielded information on the timing of at least 6 paleoearthquake events during the last 3000 years in addition to evidence of the 1943 event. The trench was excavated across an uphill-facing fault scarp ...
A 3000-Year Record of Ground-Rupturing Earthquakes along the Central North Anatolian Fault near Lake Ladik, Turkey
Fraser, Jeff; Pigati, J. S.; Hubert-Ferrari, Aurelia; Vanneste, Krıs; Avşar, Ulaş; Altinok, S. (Seismological Society of America (SSA), 2009-10-01)
The North Anatolian fault (NAF) is a similar to 1500 km long, arcuate, dextral strike-slip fault zone in northern Turkey that extends from the Karliova triple junction to the Aegean Sea. East of Bolu, the fault zone exhibits evidence of a sequence of large (M-w > 7) earthquakes that occurred during the twentieth century that displayed a migrating earthquake sequence from east to west. Prolonged human occupation in this region provides an extensive, but not exhaustive, historical record of large earthquakes ...
Understanding of the diversity of earthquake turbiditic flows in a single lake: the case of the Lake Hazar on the East Anatolian Faul
Lamair, Laura; Hage, Sophie; Hubert-ferrari, Aurelia; Avşar, Ulaş; Garcia Moreno, David; Boulvain, Frederic; Çağatay, Namık (null; 2014-08-18)
The East Anatolian Fault (EAF) is a major left-lateral strike-slip fault accommodating with the conjugate North Anatolian Fault the westward extrusion of the Anatolian Plate away from the Arabia-Eurasia collision zone. The East Anatolian Fault ruptured over most of its length during the 19th century in a series of magnitude ~7 earthquakes. During the 20th century this fault was less active with only two events of magnitude greater than 6. This absence of large earthquakes has resulted in relatively little a...
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Akkar, S; Gulkan, P (Seismological Society of America (SSA), 2002-02-01)
In 1999, Turkey was struck by two major earthquakes that occurred 86 days apart on the North Anatolian Fault system. Both earthquakes had right-lateral strike-slip mechanisms with moment magnitudes greater than 7. The number of strong-motion records obtained from the Kocaeli earthquake (17 August 1999, M-w 7.4) was 34. The second event, designated as the Bolu-Duzce earthquake (12 November 1999, M-w 7.2), triggered 20 instruments. Among the records that we have from these earthquakes, seven are from near-sou...
Assessment of tsunami resilience of Haydarpasa Port in the Sea of Marmara by high-resolution numerical modeling
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Turkey is highly prone to earthquakes because of active fault zones in the region. The Marmara region located at the western extension of the North Anatolian Fault Zone (NAFZ) is one of the most tectonically active zones in Turkey. Numerous catastrophic events such as earthquakes or earthquake/landslide-induced tsunamis have occurred in the Marmara Sea basin. According to studies on the past tsunami records, the Marmara coasts have been hit by 35 different tsunami events in the last 2000 years. The recent o...
Citation Formats
J. Fraser et al., “Development of paleoseismic trench logging and dating techniques: a case study on the Central North Anatolian Fault,” presented at the European Geosciences Union - General Assembly (15-20 Nisan 2007), 2007, Accessed: 00, 2021. [Online]. Available: