scholarly journals Seismic and a-seismic tectonic motions along the East Anatolian Fault: Seismic Gap or Creep in the east of Hazar Lake?

2017 ◽  
Vol 17 (1) ◽  
pp. 257-263 ◽  
Author(s):  
Fatih Bulut
Keyword(s):  
Seismic Gap ◽  
Hazar Lake ◽  
East Anatolian Fault

Contributions of fault gouge mineralogy on aseismic creep of active faults: the East Anatolian Fault (Eastern Turkey) as a case study

2020 ◽  
Author(s):  
Müge Yazıcı ◽  
Mehran Basmenji ◽  
Mehmet Köküm ◽  
Ugur Dogan ◽  
Cengiz Zabcı ◽  
...  
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Eastern Mediterranean ◽  
Tectonic Setting ◽  
Active Faults ◽  
Fault Gouge ◽  
Seismic Gap ◽  
Fault Rocks ◽  
Tunnel Section ◽  
East Anatolian Fault

<p>In the complex tectonic setting of the Eastern Mediterranean, the westward motion of the Anatolian Block is accommodated mainly along its boundary faults, the North Anatolian Shear Zone (NASZ) and the East Anatolian Shear Zone (EASZ). Although there are relatively limited studies on the active tectonics of the EASZ, horizontal slip rate is suggested to be of about 10 mm/yr, using geodetic data. In terms of instrumental and historical seismicity, this sinistral strike-slip fault generated surface rupturing earthquakes along almost its entire length except two segments, Palu in the northeast and Turkoglu in the southwest, creating two seismic gaps on the East Anatolian Fault (EAF), the most prominent member of the EASZ. In spite of the fact that there are some off-fault seismic activities such as the 2010 Kovancılar Earthquake (M 6.1) in the vicinity of Palu Seismic Gap, recent geodetic measurements show significant aseismic creep, almost retaining the full far plate velocity (~10 mm/yr) for about 100 km-long section of the fault. Hence, the region is continuously monitored by various types of techniques, such as GNSS, InSAR, creepmeter, seismology, and high-resolution photogrammetry.</p><p>In addition to monitoring, we investigated the mechanical signature of the creep in the fault zone using fault rocks along the Palu Segment. We collected several samples directly from the deformation zone of the EAF, which makes the boundary between limestones of the Kirkgecit Formation and the chaotic alternation of volcanics, mudstones, and limestones of the Maden Complex, at two locations. The Underground Railway Tunnel Section (39.9504°N, 38.6976°E) is cut by the fault zone where the creep signals are recorded by a creepmeter. The X-Ray Diffraction (XRD) analyses of collected samples of this locality suggest the presence of montmorillonite (smectite group) as the main clay mineral in addition to chlorite-kaolinite with a negligible amount of illite-mica minerals within the fault rocks. This preliminary result suggests a linkage between the creeping and petrophysical properties of fault rocks, which are made of the weak smectite mineral and show no-frictional healing as the expected characteristics of the creep. However, the preliminary analyses of fault gouge samples from the Murat River Section (39.9696°N, 38.7043°E) yield a small amount of smectite group clays. We are going to extend our study at different locations in order to increase the spatial resolution on the relation between the fault rocks and creep motion. This study is supported by the TUBITAK Project no. 118Y435.</p>

Estimation of site response functions for the central seismic gap of Himalaya, India

2021 ◽  
Author(s):  
Anjali Sharma ◽  
Renu Yadav ◽  
Dinesh Kumar ◽  
Ajay Paul ◽  
S. S. Teotia
Keyword(s):  
Site Response ◽  
Seismic Gap ◽  
Response Functions ◽  
Central Seismic Gap

scholarly journals Plate Coupling Mechanism of the Central Andes Subduction: Insight from Gravity Model

2019 ◽  
Vol 9 (1) ◽  
pp. 13-21
Author(s):  
Rezene Mahatsente
Keyword(s):  
Subduction Zone ◽  
Continental Crust ◽  
Gravity Model ◽  
Central Andes ◽  
High Density ◽  
Seismic Gap ◽  
Coupling Mechanism ◽  
Crust And Upper Mantle ◽  
Velocity Models ◽  
Plate Coupling

Abstract The Central Andes experienced major earthquake (Mw =8.2) in April 2014 in a region where the giant 1877 earthquake (Mw=8.8) occurred. The 2014 Iquique earthquake did not break the entire seismic gap zones as previously predicted. Geodetic and seismological observations indicate a highly coupled plate interface. To assess the locking mechanism of plate interfaces beneath Central Andes, a 2.5-D gravity model of the crust and upper mantle structure of the central segment of the subduction zone was developed based on terrestrial and satellite gravity data from the LAGEOS, GRACE and GOCE satellite missions. The densities and major structures of the gravity model are constrained by velocity models from receiver function and seismic tomography. The gravity model defined details of crustal and slab structure necessary to understand the cause of megathrust asperity generation. The densities of the upper and lower crust in the fore-arc (2970 – 3000 kg m−3) are much higher than the average density of continental crust. The high density bodies are interpreted as plutonic or ophiolitic structures emplaced onto continental crust. The plutonic or ophiolitic structures may be exerting pressure on the Nazca slab and lock the plate interfaces beneath the Central Andes subduction zone. Thus, normal pressure exerted by high density fore-arc structures and buoyancy force may control plate coupling in the Central Andes. However, this interpretation does not exclude other possible factors controlling plate coupling in the Central Andes. Seafloor roughness and variations in pore-fluid pressure in sediments along subduction channel can affect plate coupling and asperity generation.

Fitting copulas to bivariate earthquake data: the seismic gap hypothesis revisited

2008 ◽  
Vol 19 (3) ◽  
pp. 251-269 ◽  
Author(s):  
Aristidis K. Nikoloulopoulos ◽  
Dimitris Karlis
Keyword(s):  
Seismic Gap ◽  
Earthquake Data

A seismic gap past and future

Eos ◽  
1988 ◽  
Vol 69 (17) ◽  
pp. 545
Author(s):  
William Ward Maggs
Keyword(s):  
Seismic Gap

Absence of strain accumulation in the Shumagin Seismic Gap, Alaska, 1980–1987

1988 ◽  
Vol 93 (B7) ◽  
pp. 7909 ◽  
Author(s):  
M. Lisowski ◽  
J. C. Savage ◽  
W. H. Prescott ◽  
W. K. Gross
Keyword(s):  
Seismic Gap ◽  
Strain Accumulation
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