Influence of climate on the late Pleistocene depositional history of the Gulf of Gemlik (Sea of Marmara)

Eriş, Kürşad Kadir; Sabuncu, Asen; Gasperini, Luca; Polonia, Alina; Kındap, Tayfun

doi:10.1007/s00367-019-00568-0

Cited by 8 publications

(7 citation statements)

References 62 publications

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“…Van also show evidence for a following transgressional phase between 48 and 29 cal. ka BP (Kuzucuoglu et al, 2010;Eriş et al, 2019), consistent with our observations.…”

Section: Impact Of Tectonics In the Iznik Basinsupporting

confidence: 93%

“…The bathymetric survey carried out in the lake allows identifying two subaquatic faults are interpreted as markers of past low lake levels as documented in the Gemlik Bay (Eriş et al, 2019) and are offset by the fault. Microseismic data document a normal slightly dextral movement on this fault during a Ms 2 earthquake (Gurbuz et al, 2000) and a previous seismic study described this fault as a dextral P-shear or secondary synthetic shear fault ( Öztürk et al, 2009).…”

Section: Discovery Of Hitherto Unknown Subaquatic Faultsmentioning

confidence: 99%

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Paléosismologie lacustre et géophysique appliquées au lac d'Iznik (Turquie) : contribution à l'étude de la branche médiane de la Faille Nord-Anatolienne

Gastineau¹

2022

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In Turkey, the North Anatolian Fault (NAF), which accommodates the westward movement of Anatolia with respect to Eurasia, is one of the most active faults in the world.A series of earthquakes (M>6.8) have propagated from east to west during the last century. The next rupture seems to be expected in the Marmara region, south of Istanbul.However, the geometry of this fault becomes more complex in this region. It splits into three branches, one of which borders the southern Marmara Sea and Lake Iznik. This median segment of the NAF (MNAF) has very low seismicity today, and low displacements are recorded by GPS, which leads to considering it inactive. However, the city of Iznik, the cradle of Christianity, has preserved valuable historical evidence in contrast to its observations. Six destructive earthquakes have been mentioned since antiquity. To better understand the seismic hazard in this area, it is necessary to catalogue the seismic activity and locate past ruptures.The use of lakes as natural seismometers has already proved its worth. This thesis has identified two active faults after different geophysical and coring campaigns in Lake Iznik.The first part of this work focuses on the antic period. The study of short (<4m) sediment cores sampled on both sides of the E-W fault passing near the Iznik city shows that the last rupture, dating from 1065 CE, corresponds to a devastating historical earthquake.In addition to this localised rupture, numerous other event deposits are present in the sediments (laterally and temporally). This thesis has (1) differentiated between flood deposits and deposits related to slope destabilisation, most of which are associated with high confidence with historical earthquakes; (2) shown that different types of deposits are recorded for the same earthquake. At the lake scale, the difference in depositional type depends on the source-core distance. One type of deposition is only observed for the 1065 CE earthquake, which takes place in the lake, unlike the others, suggesting that this type of deposition may depend on ground motion parameters. This thesis also presents a compilation of marine and lake palaeoseismological work carried out at the scale of the northwestern part of the NAF, allowing discussion of the limitations of this method. Thus, the concept of basin sensitivity (relationship between the sedimentation rate and the triggering of a slope destabilisation due to an earthquake) does not work in the marine environment, contrary to the lacustrine environment. It is also shown that Lake Iznik records earthquakes from both the NNAF and the MNAF, while the Sea of Marmara seems to record only earthquakes from the NNAF. We also show that contrary to what was previously thought, no earthquakes of Mw>5 have been recorded on the MNAF since the 11 th century, suggesting a significant accumulation of stress on this fault since then. The last part of this thesis focuses on the long term (>2000 years) using seismic and core data. Significant lake level variations have been revealed for mo...

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“…Van also show evidence for a following transgressional phase between 48 and 29 cal. ka BP (Kuzucuoglu et al, 2010;Eriş et al, 2019), consistent with our observations.…”

Section: Impact Of Tectonics In the Iznik Basinsupporting

confidence: 93%

Section: Discovery Of Hitherto Unknown Subaquatic Faultsmentioning

confidence: 99%

Paléosismologie lacustre et géophysique appliquées au lac d'Iznik (Turquie) : contribution à l'étude de la branche médiane de la Faille Nord-Anatolienne

Gastineau¹

2022

quaternaire

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“…3-5). Such unusual layers at the transition were previously reported in sediment cores from elsewhere in the SoM, and interpreted to be due to carbonate shell accumulation, inorganic carbonate precipitation and microbial reactions induced by mixing of lacustrine and marine waters (Çağatay et al, 2009Eriş et al, 2011Eriş et al, , 2019Filikçi et al, 2017).…”

Section: Factors Controlling the Magnetic Properties Of Lacustrine An...supporting

confidence: 58%

Factors affecting thickness and frequency of turbidites triggered by earthquakes in Kumburgaz Basin, Sea of Marmara

et al. 2022

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“…This fault segment runs parallel close and south to the Boyalıca Fault so that we consider it is a segment of it. The terraces, with depths of 20, 40, and 45 m b.l.l., interpreted as markers of past low lake levels as documented in the Gemlik Bay (Eriş et al, 2019) are offset by the fault. Microseismic data document a normal slightly dextral movement on this fault during a Ms 2 earthquake (Gurbuz et al, 2000) and previous seismic study described this fault as a dextral P-shear or secondary synthetic shear fault (Öztürk et al, 2009).…”

Section: Discovery Of Hitherto Unknown Subaquatic Faultsmentioning

confidence: 99%

Active Subaquatic Fault Segments in Lake Iznik Along the Middle Strand of the North Anatolian Fault, NW Turkey

et al. 2021

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The seismic activity of the middle strand of the North Anatolian Fault (MNAF), Northwestern Turkey, is debated because of its quiescence during the instrumental period, in contrast to a significant historical activity documented by several chronicles over the last two millennia. Here, we focus on Lake Iznik, bordered by the MNAF, to get a new insight into its long-term seismicity and its tectonic setting. The study of lacustrine sediment cores reveals 14 earthquake-induced turbidites since their ages correspond to seismic events during the past two millennia. Bathymetry and high-resolution seismic reflection data allow to describe two hitherto unknown subaquatic active fault structures (the South Boyalica and Iznik faults) that belong to the MNAF system. Sediment cores sampled on both sides of the Iznik Fault document an event deposit and a sedimentary unit vertically offset of~40 cm interpreted as the last rupture during the 1065 CE destructive earthquake. Older events are supposed on this fault more than thousand years ago. Further studies will help to estimate the horizontal co-seismic offset of this oblique-slip fault and the calendar of older ruptures. The current seismic gap of thousand years on this segment greatly increases the seismic hazard in this region and must be considered in the seismic risk assessment of the NAF system. Plain Language Summary During large earthquakes, sediments are generally transported from lake slopes to the lake basin. The resulting event deposits can provide information on the recurrence of past regional earthquakes, which is crucial for seismic hazard assessment. In this study, we discovered two underwater fault structures in Lake Iznik, using geophysical methods. Studying the sedimentation on both sides of the southernmost fault, we observed an increased sedimentation rate on the hanging wall of the fault immediately after an event deposit, dated to 1077 ± 77 cal. CE. We interpreted these indicators as resulting from a co-seismic displacement along the fault plane, linked to the 1065 CE historical earthquake, which had significantly impacted the city of Iznik. We also show that most of the other event deposits in the sediment cores are confidently associated to 14 historical earthquakes since 2,000 years.

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Influence of climate on the late Pleistocene depositional history of the Gulf of Gemlik (Sea of Marmara)

Cited by 8 publications

References 62 publications

Paléosismologie lacustre et géophysique appliquées au lac d'Iznik (Turquie) : contribution à l'étude de la branche médiane de la Faille Nord-Anatolienne

Paléosismologie lacustre et géophysique appliquées au lac d'Iznik (Turquie) : contribution à l'étude de la branche médiane de la Faille Nord-Anatolienne

Factors affecting thickness and frequency of turbidites triggered by earthquakes in Kumburgaz Basin, Sea of Marmara

Active Subaquatic Fault Segments in Lake Iznik Along the Middle Strand of the North Anatolian Fault, NW Turkey

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