Variation of Fault Creep Along the Overdue Istanbul‐Marmara Seismic Gap in NW Türkiye

Abstract

The North Anatolian continental transform Fault Zone (NAFZ) bounds the Anatolian and Eurasian plates over a distance of about 1,500 km between the Karliova triple junction in the east and the Northern Aegean in the west (e.g.,

Spatio-temporal variations of seismic coupling along a transform fault: the western North Anatolian Fault Zone

“…1 ) represent a wider fault zone, accommodating the shape of the basin and the seismicity follows the mapped fault segments (Wollin et al 2018 ). Recently, earthquake repeaters have been identified in this part, suggesting that the tectonic strain is partially released aseismically through fault creep (Schmittbuhl et al 2015(Schmittbuhl et al , 2016Bohnhoff et al 2017 a;Uchida et al 2019 ;Becker et al 2023 ). This is also supported by seafloor geodetic measurements (Yamamoto et al 2019 ).…”

“…Starting in 1939 with the Erzincan M w 7.9 earthquake, a sequence of large-magnitude ( M > 7) earthquakes propagated westwards, with the most recent earthquakes being the 1999 M w 7.4 Izmit and M w 7.1 D üzce occurring east of the Sea of Marmara (Pinar et al 2001 ;Barka et al 2002 ;Bohnhoff et al 2016b ). Together with the 1912 Ganos/Murefte M w 7.4 earthquake in western Marmara, the entire NAFZ ruptured in M > 7 earthquakes in the 20th century except for the Main Marmara Fault below the Sea of Marmara (MMF) which is considered a seismic gap that is partly locked (Bohnhoff et al 2013 ;Ergintav et al 2014 ;Becker et al 2023 ). There, the last major ( M 7.4) earthquake occurred in 1766.…”

“…For example, selected areas such as the Western High, along the Armutlu peninsula and west of the gulf of Gemlik (Fig.1for locations) show a high seismic coupling of up to 100 per cent (Fig.5).Several studies discussed the deformation modes of the MMF. Earthquake repeaters have been observed to occur on the Western High and Central Basin, suggesting the occurrence of aseismic slip(Schmittbuhl et al 2016 ;Bohnhoff et al 2017 ;Yamamoto et al 2019 ;Becker et al 2023 ). At these locations,Becker et al ( 2023 ) determined creep rates that might accommodate locally up to 40 per cent of the tectonic deformation.…”

“…Earthquake repeaters have been observed to occur on the Western High and Central Basin, suggesting the occurrence of aseismic slip(Schmittbuhl et al 2016 ;Bohnhoff et al 2017 ;Yamamoto et al 2019 ;Becker et al 2023 ). At these locations,Becker et al ( 2023 ) determined creep rates that might accommodate locally up to 40 per cent of the tectonic deformation. Therefore, the high seismic coupling here obtained for the Western High region suggests that the presence of aseismic deformation in the area is also promoting locally the occurrence of seismicity (e.g Marsan et al 2017 )…”