Estimation of successive coseismic vertical offsets using coeval sedimentary events – application to the southwestern limit of the Sea of Marmara's Central Basin (North Anatolian Fault)

Abstract. In the deep part of the Sea of Marmara (Turkey), the sedimentation developing upon the North Anatolian Fault is strongly influenced by the associated seismic activity, through gravity reworking (fluidized landslides) and tsunamis. Specific layers (homogenites + turbidites, HmTu), representing individual sedimentary events, have been characterized along three giant piston cores retrieved from the Çinarcik and Central (or Orta) basins. Pre-Holocene, nonmarine sediments, were analyzed, representing the last 12–17 kyr BP (before present). For a 2 kyr long interval, 11 events could be precisely correlated on both sides of the Central Basin's southwestern scarp. For each of them, based on the specific depositional process, the thickness difference between the two sites was considered as a direct estimation of the vertical component of a coeval coseismic offset. The homogenite (upper) component accounts for the major part of the thickness difference (ranging from 36 to 144 cm). These offsets were considered as likely representing dominantly vertical throws, along the transtensional southwestern boundary of the inner, pull-apart Central Basin. In terms of natural hazards, further investigations on this local behavior should rather be directed to tsunami genesis.

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Estimation of successive co-seismic vertical offsets using coeval sedimentary events – application to the Sea of Marmara's Central Basin (North Anatolian Fault)

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-2-4069-2014 ◽

2014 ◽

Vol 2 (6) ◽

pp. 4069-4100

Author(s):

C. Beck ◽

C. Campos ◽

K. Eriş ◽

N. Çağatay ◽

B. Mercier de Lepinay ◽

...

Keyword(s):

Seismic Activity ◽

Major Part ◽

Vertical Component ◽

North Anatolian Fault ◽

Central Basin ◽

Deep Part ◽

Sea Of Marmara ◽

Direct Estimation ◽

The North ◽

Depositional Process

Abstract. In the deep part of the Sea of Marmara (Turkey), the sedimentation developing upon the North Anatolian Fault is strongly influenced by the associated seismic activity. Specific layers (homogenites-turbidites), representing individual sedimentary events, have been characterized along three giant piston cores retrieved from Çinarcik and Central (or Orta) basins. Analyzed sediments represent the last 12 to 17 kyr BP. For a 2 kyr-lasting interval, 11 events could be precisely correlated on both sides of the Central Basin's southern scarp. For each of them, based on the specific depositional process, the thickness difference between the two sites was considered as a direct estimation of the vertical component of a coeval co-seismic offset. The homogenite (upper) term accounts for the major part of the thickness difference. The 6 most significant values range from 36 cm to 144 cm and are likely representing dominantly normal throws, with estimated paleomagnitudes (Mw) ranging from 5.9 to 6.6.

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Heat flow in the Sea of Marmara Central Basin: Possible implications for the tectonic evolution of the North Anatolian fault

Geology ◽

10.1130/g32192.1 ◽

2011 ◽

Vol 40 (1) ◽

pp. 3-6 ◽

Cited By ~ 24

Author(s):

C. Grall ◽

P. Henry ◽

D. Tezcan ◽

B. Mercier de Lepinay ◽

A. Becel ◽

...

Keyword(s):

Heat Flow ◽

Tectonic Evolution ◽

North Anatolian Fault ◽

Central Basin ◽

Sea Of Marmara ◽

The North

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Dynamic models of earthquakes on the North Anatolian fault zone under the Sea of Marmara: Effect of hypocenter location

Geophysical Research Letters ◽

10.1029/2008gl035037 ◽

2008 ◽

Vol 35 (18) ◽

Cited By ~ 29

Author(s):

David D. Oglesby ◽

P. Martin Mai ◽

Kuvvet Atakan ◽

Stefano Pucci

Keyword(s):

Fault Zone ◽

Dynamic Models ◽

North Anatolian Fault ◽

Sea Of Marmara ◽

North Anatolian Fault Zone ◽

Hypocenter Location ◽

The North

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The North Anatolian fault in the Sea of Marmara

Journal of Geophysical Research Atmospheres ◽

10.1029/2002jb001862 ◽

2003 ◽

Vol 108 (B4) ◽

Cited By ~ 110

Author(s):

X. Le Pichon ◽

N. Chamot-Rooke ◽

C. Rangin ◽

A. M. C. Sengör

Keyword(s):

North Anatolian Fault ◽

Sea Of Marmara ◽

The North

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Locking Behavior of Main Marmara Fault in Western Turkey During Interseismic Period

10.5194/egusphere-egu2020-10682 ◽

2020 ◽

Author(s):

Zeynep Yılmaz ◽

Ali Özgün Konca ◽

Semih Ergintav

Keyword(s):

3D Structure ◽

Slip Rate ◽

Fault Slip ◽

North Anatolian Fault ◽

Gps Data ◽

Strain Accumulation ◽

Sea Of Marmara ◽

Western Turkey ◽

The North ◽

Fault Slip Rate

The North Anatolian Fault (NAF) produced multiple earthquakes of M>7 throughout the 20th century, while the part of NAF beneath Sea of Marmara did not rupture during this period. Analysis of the Main Marmara Fault's interseismic behavior, the most active branch of the North Anatolian Fault in this region, in terms of locking depth and fault slip rate is critical for evaluating the region's seismic risk with a population of more than 20 million, as it provides information about the seismic moment deficit that may release in a potential future earthquake.In this study, we modeled the Main Marmara Fault's interseismic locking with realistic geometry and 3D structure including sedimentary basins, by implementing a 3D finite element approach and using interseismic GPS velocities. We have optimized the fits with GPS data by evaluating cases where each fault segment is constrained by a fault slip rate below a predefined locking depth ranging from 0 to 20 km. Preliminary models reveal that a difference in locking depth is required between the Western Marmara and the eastern end of the Ganos Segment entering the Sea of Marmara. This result, which is consistent with seismicity studies and other previous studies using 1D profiles shows that the strain accumulation under Western Marmara is less and that the locking depths or couplings are not similar in these two segments. For the Princes' Islands Segment, further analysis is required due to complexity in the GPS data. Recent earthquakes along Silivri also indicate that the strain accumulation is complex with most mechanisms showing significant thrust component. We have also calculated various possible strain accumulation patterns and compared the strain rate field around the Main Marmara Fault. Our results show that in most cases the change in the seismicity of each segment is consistent with the interseismic behavior associated with its fault locking.(This research has been supported by Bo&#287;azi&#231;i University Scientific Research Projects Coordination Unit. Project Number: 15022, 2019)

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