Basin progress: active deformation analysis by tectonostratigraphic elements and geophysical methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

2021 ◽  
Author(s):  
Bülent Doğan ◽  
Metin Aşci ◽  
Ahmet Karakaş ◽  
Ertan Pekşen ◽  
Arzu Erener ◽  
...  
Keyword(s):  
Geophysical Methods ◽  
North Anatolian Fault ◽  
Fault System ◽  
Deformation Analysis ◽  
Marmara Region ◽  
Active Deformation

scholarly journals Basin Progress – Active Deformation Analysis by Tectonostratigraphic Elements and Geophysical Methods on North Anatolian Fault System (Eastern Marmara Region, Turkey)

2021 ◽  
Author(s):  
Bülent Doğan ◽  
Metin Aşcı ◽  
Ahmet Karakaş ◽  
Ertan Pekşen ◽  
Arzu Erener ◽  
...  
Keyword(s):  
Strike Slip ◽  
North Anatolian Fault ◽  
Fault System ◽  
Magnetic Method ◽  
Lake Basin ◽  
Active Deformation ◽  
Southern Boundary ◽  
The North ◽  
Dextral Strike Slip ◽  
Northern Branch

Abstract The Northern Branch of the North Anatolian Fault System controls and deforms the Izmit Basin and the Sapanca Lake Basin in the study area. Unlike the Sapanca Lake Basin, the oblique normal faults with WNW–ESE trending with maximum length of 5 km in the south of the basin have contributed to the deformation process in the formation of Izmit Basin. The fault sets mainly incline to the north. The N-S width of the dextral strike-slip active deformation was determined as 9 km at Izmit basin and 3.8 km at Sapanca Lake basin. Further, the minimum principal stress axes (σ3) vary in the trending ranges of N11°-74° E, which are caused by the transtensional stresses associated with strike-slip faulting in the Izmit Basin by a different tectonic source than the Sapanca Lake Basin. Besides, the crust depth of main strand of NAFS-NB was determined up to 1112 m by magnetic method. The secondary faults were determined by both magnetic and resistivity methods up to a depth of 110 m. The depression area between Izmit bay and Sapanca Lake on the northern Anatolian fault is an integrated basin with two dextral strike-slip tectonic origins. Thus, the Izmit Basin, along with the main strike-slip faulting, has been developed in the asymmetric negative flower structure, where only the southern boundary has become a fault. The Sapanca Lake Basin is a lazy-Z-shaped pull-apart system formed by the E–W trending fault as a releasing bend. A simple shear deformation ellipsoid with a long axis of approximately 35 km on the Northern Branch of the North Anatolian Fault System is defined for the Izmit – Sapanca integrated basin. Therefore, intra-basin deposits have different depths estimated from the gravity data in the Izmit – Sapanca integrated basin, and the maximum sediment thickness estimated is 2200 m in the middle of the Izmit Basin.

Recent and active deformation in the North Evia domain, a diffuse plate boundary between Eurasia and Aegean plates in the Western termination of the North Anatolian Fault. 

2021 ◽  
Author(s):  
Fabien Caroir ◽  
Frank Chanier ◽  
Virginie Gaullier ◽  
Julien Bailleul ◽  
Agnès Maillard-Lenoir ◽  
...  
Keyword(s):  
Fault Zone ◽  
Plate Boundary ◽  
Fault Zones ◽  
North Anatolian Fault ◽  
Fault System ◽  
Eurasian Plate ◽  
Slip Rates ◽  
The North ◽  
South West ◽  
North Aegean

<p>The Anatolia-Aegean microplate is currently extruding toward the South and the South-West. This extrusion is classically attributed to the southward retreat of the Aegean subduction zone together with the northward displacement of the Arabian plate. The displacement of Aegean-Anatolian block relative to Eurasia is accommodated by dextral motion along the North Anatolian Fault (NAF), with current slip rates of about 20 mm/yr. The NAF is propagating westward within the North Aegean domain where it gets separated into two main branches, one of them bordering the North Aegean Trough (NAT). This particular context is responsible for dextral and normal stress regimes between the Aegean plate and the Eurasian plate. South-West of the NAT, there is no identified major faults in the continuity of the NAF major branch and the plate boundary deformation is apparently distributed within a wide domain. This area is characterised by slip rates of 20 to 25 mm/yr relative to Eurasian plate but also by clockwise rotation of about 10° since ca 4 Myr. It constitutes a major extensional area involving three large rift basins: the Corinth Gulf, the Almiros Basin and the Sperchios-North Evia Gulf. The latter develops in the axis of the western termination of the NAT, and is therefore a key area to understand the present-day dynamics and the evolution of deformation within this diffuse plate boundary area.</p><p>Our study is mainly based on new structural data from field analysis and from very high resolution seismic reflexion profiles (Sparker 50-300 Joules) acquired during the WATER survey in July-August 2017 onboard the R/V “Téthys II”, but also on existing data on recent to active tectonics (i.e. earthquakes distribution, focal mechanisms, GPS data, etc.). The results from our new marine data emphasize the structural organisation and the evolution of the deformation within the North Evia region, SW of the NAT.</p><p>The combination of our structural analysis (offshore and onshore data) with available data on active/recent deformation led us to define several structural domains within the North Evia region, at the western termination of the North Anatolian Fault. The North Evia Gulf shows four main fault zones, among them the Central Basin Fault Zone (CBFZ) which is obliquely cross-cutting the rift basin and represents the continuity of the onshore Kamena Vourla - Arkitsa Fault System (KVAFS). Other major fault zones, such as the Aedipsos Politika Fault System (APFS) and the Melouna Fault Zone (MFZ) played an important role in the rift initiation but evolved recently with a left-lateral strike-slip motion. Moreover, our seismic dataset allowed to identify several faults in the Skopelos Basin including a large NW-dipping fault which affects the bathymetry and shows an important total vertical offset (>300m). Finally, we propose an update of the deformation pattern in the North Evia region including two lineaments with dextral motion that extend southwestward the North Anatolian Fault system into the Oreoi Channel and the Skopelos Basin. Moreover, the North Evia Gulf domain is dominated by active N-S extension and sinistral reactivation of former large normal faults.</p>

Earth Sciences

2005 ◽  
Author(s):  
Glennda Chui
Keyword(s):  
Natural Hazards ◽  
Plate Tectonics ◽  
Earth Science ◽  
North Anatolian Fault ◽  
The Other ◽  
Fault System ◽  
Military Officers ◽  
Apartment Building ◽  
The North ◽  
Scientists And Engineers

In August 1999, I stood in the ruins of a collapsed apartment building near Izmit, Turkey—one of 60,000 buildings destroyed in 40 seconds by the most powerful earthquake to strike a major city in nearly a century. It was a modern building surrounded by trees and greenery. A couch and a table stood intact in a room bright with potted flowers, now open to the air. A woman's coat had been carefully draped over the remains of a wall. As the stench of death rose around us, I wondered if the coat's owner was buried in the rubble beneath my feet. I was sent to Turkey to chase the science—to bring home lessons for readers who live near a strikingly similar fault system in California. But as I surveyed the damage with a team of scientists and engineers, there was no separating the science from the politics. Covered with a fine film of sweat mixed with dust from crumbled buildings and lime that had been scattered to prevent the spread of disease, we saw firsthand how corruption and greed had conspired with the forces of nature to kill more than 17,000 people. Some buildings were constructed right on the North Anatolian Fault. Its mole-like tracks plowed through barracks that had collapsed on 120 military officers, a highway overpass that fell on a bus, a bridge whose failure cut off access and aid to four villages. Researchers found concrete that was crumbly with seashells, chunks of Styrofoam where reinforcing metal bars should have been. Yet some well-reinforced buildings nicked or even pierced by the fault came through just fine, including an apartment building that moved 10 feet and had its front steps sliced off. Another home was cut in two; half collapsed, the other survived with windows intact. “How the hell?” marveled one engineer. “There's no way that building should stand in an earthquake.” That blend of science, politics, and human nature is just part of what makes earth science so compelling. It goes far beyond the academics of geology and plate tectonics to embrace earthquakes, floods, hurricanes, volcanoes, landslides—natural hazards that affect thousands of people and change the course of civilization.

Transpressional deformation in the mantle below the North Anatolian fault system, Turkey

2020 ◽  
Author(s):  
Basil Tikoff ◽  
Vasili Chatzaras ◽  
Timothy Chapman ◽  
Naomi Barshi ◽  
Ercan Aldanmaz ◽  
...  
Keyword(s):  
Fault Zone ◽  
Electron Backscatter Diffraction ◽  
Preferred Orientation ◽  
North Anatolian Fault ◽  
Mantle Xenoliths ◽  
Fault System ◽  
Alkali Basalts ◽  
Crystallographic Preferred Orientation ◽  
The North ◽  
Backscatter Diffraction

<p>The North Anatolian Fault Zone (NAFZ) is a 1200-km-long, dextral intracontinental transform fault zone, and initiated ca. 13–11 Ma ago.  The NAFZ formed in response to the N-S convergence of the Eurasian and Arabian plates, accommodated by the westward motion of the Anatolia plate relative to Eurasia plate.  Mantle xenoliths were sampled in late Miocene (11.68±0.25 to 6.47±0.47 Ma) alkali basalts and basanites, immediately N of the trace of the North Anatolian fault, and were previously interpreted to sample the mantle portion of the North Anatolian fault/shear zone at depth.  The studied xenoliths are mainly spinel lherzolites and harzburgites.  Equilibration temperatures estimated from two-pyroxene geothermometers range from 775 to 975 °C, while pressures estimated from the Cr in clinopyroxene geobarometer and pseudosection modelling range from 12 to 22 kbar, which correspond to depths of 40–80 km.  We used high‐resolution X-ray computed tomography to quantify the xenolith fabric defined by the 3D shape preferred orientation of spinel grains.  Spinel displays dominantly oblate fabric ellispoids, consistent with flattening strain.  Olivine has two main crystallographic preferred orientation patterns, the axial-[010] and the A-type, determined with electron backscatter diffraction.  The axial-[010] pattern is consistent with the spinel fabric and other microstructures that show flattening strains.  To further constrain the strain path, we analyze the crystallographic vorticity axes in olivine, which show a complex pattern.  Our results are consistent with an interpretation of transpressional deformation in the upper mantle below the NAFZ, during the early stages of the development of the transform system.  Transpressional deformation is consistent with collision-induced, strike-slip extrusion of Anatolia.</p>

SEPTEMBER 26, 2019 Mw5.8 MARMARA SEA-SILIVRI (ISTANBUL) EARTHQUAKE: ANALYSIS OF GROUND MOTION RECORDS

2020 ◽  
Author(s):  
Seyhan Okuyan Akcan ◽  
Can Zulfikar
Keyword(s):  
Ground Motion ◽  
North Anatolian Fault ◽  
Marmara Region ◽  
Marmara Sea ◽  
The North ◽  
Tectonically Active ◽  
Earthquake Research ◽  
Earthquake Research Institute ◽  
Ground Motion Records ◽  
Almost All

<p>Marmara region located on the western end of the North Anatolian Fault Zone is a tectonically active region in Turkey. There have been frequent severe earthquakes in the region and will continue to occur. There was no serious earthquake in the region after the 1999 Mw7.4 Kocaeli and Mw7.2 Düzce earthquakes. A Marmara Sea offshore earthquake Mw5.8 close to Silivri Town of Istanbul Metropolitan City has occurred on September 26, 2019 daytime at 13:59. The earthquake happened at the coordinate of 40.87N – 28.19E with a depth of 7.0km on the Kumburgaz segment of the North Anatolian Fault line. It was felt in almost all Marmara region. In some settlements in Istanbul City, slight to moderate damages were observed. A foreshock earthquake of Mw4.8 occurred on the same segment on 24 September, 2019. 150 aftershock events ranging from M1.0 to M4.1 have been recorded within the 24 hours after the mainshock. The ground motions have been recorded in the region by the several institutions including AFAD (Disaster and Emergency Management Presidency), KOERI (Kandilli Observatory and Earthquake Research Institute) and IGDAS (Istanbul Gas Distribution Industry and Trade Inc.). The ground motion records and selected parameters have been examined in this study. The ground motion parameters (MMI, PGA, PGV, Sa, Sv, Sd) distribution have been achieved and checked by the recent NGA-West2 ground motion prediction equations (GMPEs); ASK2014, CY2014 and BSSA2014. The compatibility of the GMPEs for a moderate size Marmara Sea earthquake has been examined.</p>

Integration of geophysical methods and fractures study for the Vallès geothermal system characterization (NE Spain)

2020 ◽  
Author(s):  
Gemma Mitjanas ◽  
Juanjo Ledo ◽  
Pilar Queralt ◽  
Gemma Alías ◽  
Perla Piña ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Geophysical Methods ◽  
Normal Fault ◽  
Hot Water ◽  
Fault System ◽  
Geothermal System ◽  
Thin Sections ◽  
Main Structure ◽  
Geological Map ◽  
Ne Spain

<p>The Vallès geothermal system is located in the Catalan Coastal Ranges (CCR) (NE Spain). The CCR are formed by horst and graben structures limited by NE-SW and ENE-WSW striking normal faults, developed during the opening of the Valencia Trough (northwestern Mediterranean) (Gaspar-Escribano et al., 2004). In the Vallès Basin area, the thermal anomaly is located in the northeastern horst-graben limit, where a highly fractured Hercynian granodiorite is in contact with Miocene rocks by a major normal fault. This main structure seems to control the heat and the hot-water flow, nevertheless, the geological structure of this area, as well as the role of the Vallès normal fault, is poorly understood.</p><p>Magnetotellurics and gravity methods together with a detailed geological map have been applied in this area to understand the main structure. Although the geophysical part makes up most of the study, we are also elaborating a detailed geological map of the area, making a fractures study at different scales. We are working with DEM alignments analysis, and fractures study from outcrops and thin sections.</p><p>Our preliminary results in gravity show a strong gravity gradient in the NE-SW Vallès half-graben system and the recent MT profiles image the main fault of that system (Vallès normal fault). These results show a basin geometry with the major thickness of the basin towards the depocenter, disagreeing with the roll-over geometry assumed in previous works.</p><p>Interpretations of the fractures study, together with geophysical data and models, have allowed a preliminary characterization of damage zones associated with the fault system, which are directly related to the fluid flow and the hot springs. The nature of this damage zones could be related to relay ramps, commonly regarded as efficient conduits for fluid flow (Fossen and Rotevatn, 2016).</p>

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