Western Extension of the North Anatolian Fault and Associated Structures in the Gulf of Saros, NE Aegean Sea

2002 ◽  
pp. 61-70
Author(s):  
M. N. Çağatay ◽  
N. Görür ◽  
B. Alpar
Keyword(s):  
Aegean Sea ◽  
North Anatolian Fault ◽  
The North

scholarly journals Temporal variations of the fractal properties of seismicity in the western part of the north Anatolian fault zone: possible artifacts due to improvements in station coverage

1995 ◽  
Vol 2 (3/4) ◽  
pp. 147-157 ◽  
Author(s):  
A. O. Öncel ◽  
Ö. Alptekin ◽  
I. Main
Keyword(s):  
Fault Zone ◽  
Statistical Significance ◽  
Rock Fracture ◽  
Aegean Sea ◽  
B Value ◽  
Temporal Variations ◽  
North Anatolian Fault ◽  
North Anatolian Fault Zone ◽  
The North ◽  
Northern Aegean Sea

Abstract. Seismically-active fault zones are complex natural systems exhibiting scale-invariant or fractal correlation between earthquakes in space and time, and a power-law scaling of fault length or earthquake source dimension consistent with the exponent b of the Gutenberg-Richter frequency-magnitude relation. The fractal dimension of seismicity is a measure of the degree of both the heterogeneity of the process (whether fixed or self-generated) and the clustering of seismic activity. Temporal variations of the b-value and the two-point fractal (correlation) dimension Dc have been related to the preparation process for natural earthquakes and rock fracture in the laboratory These statistical scaling properties of seismicity may therefore have the potential at least to be sensitive short- term predictors of major earthquakes. The North Anatolian Fault Zone (NAFZ) is a seismicallyactive dextral strike slip fault zone which forms the northern boundary of the westward moving Anatolian plate. It is splayed into three branches at about 31oE and continues westward toward the northern Aegean sea. In this study, we investigate the temporal variation of Dc and the Gutenberg-Richter b-value for seismicity in the western part of the NAFZ (including the northern Aegean sea) for earthquakes of Ms > 4.5 occurring in the period between 1900 and 1992. b ranges from 0.6-1.6 and Dc from 0.6 to 1.4. The b-value is found to be weakly negatively correlated with Dc (r=-0.56). However the (log of) event rate N is positively correlated with b, with a similar degree of statistical significance (r=0.42), and negatively correlated with Dc (r=-0.48). Since N increases dramatically with improved station coverage since 1970, the observed negative correlation between b and Dc is therefore more likely to be due to this effect than any underlying physical process in this case. We present this as an example of how man-made artefacts of recording can have similar statistical effects to underlying processes.

Coda-attenuation imaging of the North Anatolian Fault Zone, northern Turkey

2021 ◽  
Author(s):  
Panayiota Sketsiou ◽  
Luca De Siena ◽  
David G. Cornwell
Keyword(s):  
Fault Zone ◽  
Seismic Velocity ◽  
Aegean Sea ◽  
North Anatolian Fault ◽  
The North ◽  
Coda Attenuation ◽  
High Resolution Models ◽  
Attenuation Imaging ◽  
Geological Units ◽  
Quality Factor Q

<p>The North Anatolian Fault (NAF), a right-lateral strike-slip fault spanning 1500 km in length, stretches across northern Turkey and it marks the boundary between the Eurasian and Anatolian plates. Nucleating in the east, at the Karliova triple junction and reaching the Aegean Sea at the west, it is a particularly active fault zone with a series of migrating high-magnitude earthquakes. Using 6445 Z-component waveforms from a temporary seismic network in the area (Dense Array for North Anatolia – DANA), this study aims to investigate the western part of the NAF, which splays into a northern and southern branch. Coda attenuation imaging is utilised for imaging the absorption characteristics of the area, as it can be used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. The absorption structure is recovered by inverting for the coda attenuation quality factor, Q<sub>c</sub>, at frequencies between 3-18 Hz, using sensitivity kernels. The extensive seismicity in the area, as well as the density of the seismic stations, provide high-resolution models of 0.04-0.05 degrees in spacing. The scattering structure of the region is imaged using peak-delay time, which is used as a direct measure for multiple forward scattering. Preliminary results show a clear change in scattering between the Istanbul and Sakarya zones, north and south of the fault respectively, with the scattering increasing from north to south at lower frequencies and decreasing at higher frequencies. At a smaller scale, absorption and scattering anomalies appear to outline contrasting geological units beneath the DANA network.</p>

scholarly journals Tsunamigenic potential of a Holocene submarine landslide along the North Anatolian Fault (North Aegean Sea, off Thasos Island): insights from numerical modeling

2018 ◽  
Author(s):  
Alexandre Janin ◽  
Mathieu Rodriguez ◽  
Dimitris Sakellariou ◽  
Vasilis Lykousis ◽  
Christian Gorini
Keyword(s):  
Tsunami Wave ◽  
Aegean Sea ◽  
Submarine Landslide ◽  
North Anatolian Fault ◽  
Potential Hazard ◽  
Submarine Landslides ◽  
The North ◽  
North Aegean ◽  
North Aegean Sea ◽  
Water Height

Abstract. The North Anatolian Fault in the northern Aegean Sea triggers frequent earthquakes of magnitude up to Mw ∼ 7. This seismicity can be a source of modest tsunamis for the surrounding coastlines with less than 50 cm height according to numerical modelling and analysis of tsunami deposits. However, other tsunami sources may be involved, like submarine landslides. We assess the severity of this potential hazard by performing numerical simulations of tsunami generation and propagation from a Holocene landslide (1.85 km3 in volume) identified off Thasos island. We use a model coupling the simulation of the submarine landslide, assimilated to a granular flow, to the propagation of the tsunami wave. The results of these simulations show that a tsunami wave of water height between 1.10 m and 1.65 m reaches the coastline at Alexandroupolis (58.000 inhabitants) one hour after the triggering of the landslide. In the same way, tsunamis waves of water height between 0.80 m and 2.00 m reach the coastline of the Athos peninsula 9 min after the triggering of the landslide. Landslide tsunamis should not be neglected as a potential source of tsunami in the area. Despite numerous earthquakes of Mw > 7 and strong detrital input (on the order of 30 cm ka−1), only a few Holocene landslides have been recognized so far, asking the question of the relationships between seismicity and landslide frequency in the area.

Propagation and termination of a strike slip fault in an extensional domain: The westward growth of the North Anatolian Fault into the Aegean Sea

2018 ◽  
Vol 745 ◽  
pp. 183-195 ◽  
Author(s):  
George Ferentinos ◽  
Nikos Georgiou ◽  
Dimitris Christodoulou ◽  
Maria Geraga ◽  
George Papatheodorou
Keyword(s):  
Aegean Sea ◽  
Strike Slip ◽  
North Anatolian Fault ◽  
Strike Slip Fault ◽  
The North

scholarly journals Morphotectonic Structures along the Southwestern Margin of Lesvos Island, and Their Interrelation with the Southern Strand of the North Anatolian Fault, Aegean Sea, Greece

GeoHazards ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 415-429
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Aegean Sea ◽  
Strike Slip ◽  
North Anatolian Fault ◽  
Strike Slip Fault ◽  
Normal Faults ◽  
Western Basin ◽  
The North ◽  
Southern Margin ◽  
Main Basin

A hydrographic survey of the southwestern coastal margin of Lesvos Island (Greece) was conducted by the Naftilos vessel of the Hellenic Hydrographic Service. The results have been included in a bathymetric map and morphological slope map of the area. Based on the neotectonic and seismotectonic data of the broader area, a morphotectonic map of Lesvos Island has been compiled. The main feature is the basin sub-parallel to the coast elongated Lesvos Basin, 45 km long, 10–35 km wide, and 700 m deep. The northern margin of the basin is abrupt, with morphological slopes towards the south between 35° and 45° corresponding to a WNW-ESE normal fault, in contrast with the southern margin that shows a gradual slope increase from 1° to 5° towards the north. Thus, the main Lesvos Basin represents a half-graben structure. The geometry of the main basin is interrupted at its eastern segment by an oblique NW-SE narrow channel of 650 m depth and 8 km length. East of the channel, the main basin continues as a shallow Eastern Basin. At the western part of the Lesvos margin, the shallow Western Basin forms an asymmetric tectonic graben. Thus, the Lesvos southern margin is segmented in three basins with different morphotectonic characteristics. At the northwestern margin of Lesvos, three shallow basins of 300–400 m depth are observed with WNW-ESE trending high slope margins, probably controlled by normal faults. Shallow water marine terraces representing the last low stands of the glacial periods are observed at 140 m and 200 m depth at the two edges of the Lesvos margin. A secondary E-W fault disrupts the two terraces at the eastern part of the southern Lesvos margin. The NE-SW strike-slip fault zone of Kalloni-Aghia Paraskevi, activated in 1867, borders the west of the Lesvos Basin from the shallow Western Basin. The Lesvos bathymetric data were combined with those of the eastern Skyros Basin, representing the southern strand of the North Anatolian Fault in the North Aegean Sea, and the resulted tectonic map indicates that the three Lesvos western basins are pull-aparts of the strike-slip fault zone between the Skyros Fault and the Adramytion (Edremit) Fault. The seismic activity since 2017 has shown the co-existence of normal faulting and strike-slip faulting throughout the 90 km long Lesvos southern margin.

scholarly journals Tsunamigenic potential of a Holocene submarine landslide along the North Anatolian Fault (northern Aegean Sea, off Thasos island): insights from numerical modelling

2019 ◽  
Vol 19 (1) ◽  
pp. 121-136 ◽  
Author(s):  
Alexandre Janin ◽  
Mathieu Rodriguez ◽  
Dimitris Sakellariou ◽  
Vasilis Lykousis ◽  
Christian Gorini
Keyword(s):  
Numerical Modelling ◽  
Tsunami Wave ◽  
Aegean Sea ◽  
Submarine Landslide ◽  
North Anatolian Fault ◽  
Potential Hazard ◽  
Submarine Landslides ◽  
The North ◽  
Northern Aegean Sea ◽  
Water Height

Abstract. The North Anatolian Fault in the northern Aegean Sea triggers frequent earthquakes of magnitudes up to Mw∼7. This seismicity can be a source of modest tsunamis for the surrounding coastlines with less than 50 cm height according to numerical modelling and analysis of tsunami deposits. However, other tsunami sources may be involved, like submarine landslides. We assess the severity of this potential hazard by performing numerical simulations of tsunami generation and propagation from a Holocene landslide (1.85 km3 in volume) identified off Thasos. We use a model coupling the simulation of the submarine landslide, assimilated to a granular flow, to the propagation of the tsunami wave. The results of these simulations show that a tsunami wave of water height between 1.10 and 1.65 m reaches the coastline at Alexandroupoli (58 000 inhabitants) 1 h after the triggering of the landslide. In the same way, tsunami waves of water height between 0.80 and 2.00 m reach the coastline of the Athos peninsula 9 min after the triggering of the landslide. Despite numerous earthquakes of Mw>7 and strong detrital input (on the order of 30 cm ka−1), only a few Holocene landslides have been recognized so far, asking for tsunami recurrence in this area.

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