Istanbul's earthquake hot spots: Geodetic constraints on strain accumulation along faults in the Marmara seismic gap

Ergintav, Semih; Reilinger, Robert; Çakmak, R.; Floyd, Michael; Çakır, Ziyadin; Doǧan, Uǧur; King, Robert W.; McClusky, S.; Özener, Haluk

doi:10.1002/2014gl060985

Cited by 150 publications

(205 citation statements)

References 25 publications

(52 reference statements)

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“…This is significantly less than longterm slip rates predicted for the NAF in this area [Flerit et al, 2003;Reilinger et al, 2006;Hergert and Heidbach, 2010] or from distant on-land GPS data [Ergintav et al, 2014]. If this slip deficit corresponds to a steady state behavior of the fault, it implies that the NAF is currently accumulating stress at the surface.…”

Section: 1002/2016gl069600mentioning

confidence: 73%

“…Although Bohnhoff et al [2016] suggest that the maximum expected earthquake in the Istanbul area would probably not exceed a magnitude 7.5, geomechanical models generally predict high strain accumulation along the ISS, sufficient to produce a magnitude 7+ event [Hergert and Heidbach, 2010;Pondard et al, 2007;Armijo et al, 2005;. Conversely, Ergintav et al [2014] proposed that the ISS is aseismically creeping with strain accumulation less than 2 mm/yr, based on GPS data from distant and sparsely distributed land stations. Assessing whether the ISS is locked or aseismically creeping is crucial for estimating its seismic hazard potential and a major challenge using conventional methods.…”

Section: Introductionmentioning

confidence: 99%

“…Armijo et al [2002]. Arrows with 95% confidence ellipses represent the velocity field derived from permanent GPS stations, relative to stable Eurasia [Ergintav et al, 2014]. (c) Layout of the offshore geodetic network, overlain on a high-resolution AUV bathymetry map [Geli and Henry, 2009].…”

Section: Introductionmentioning

confidence: 99%

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No significant steady state surface creep along the North Anatolian Fault offshore Istanbul: Results of 6 months of seafloor acoustic ranging

Sakic

Piete

Ballu

et al. 2016

Geophysical Research Letters

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The submarine Istanbul‐Silivri fault segment, within 15 km of Istanbul, is the only portion of the North Anatolian Fault that has not ruptured in the last 250 years. We report first results of a seafloor acoustic ranging experiment to quantify current horizontal deformation along this segment and assess whether the segment is creeping aseismically or accumulating stress to be released in a future event. Ten transponders were installed to monitor length variations along 15 baselines. A joint least squares inversion for across‐fault baseline changes, accounting for sound speed drift at each transponder, precludes fault displacement rates larger than a few millimeters per year during the 6 month observation period. Forward modeling shows that the data better fit a locked state or a very moderate surface creep—less than 6 mm/yr compared to a far‐field slip rate of over 20 mm/yr—suggesting that the fault segment is currently accumulating stress.

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Section: 1002/2016gl069600mentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

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No significant steady state surface creep along the North Anatolian Fault offshore Istanbul: Results of 6 months of seafloor acoustic ranging

Sakic

Piete

Ballu

et al. 2016

Geophysical Research Letters

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“…We are aware that this is a simplification and may not be true everywhere (e.g. Ergintav et al 2014); the coupling coefficient is indeed a crucial parameter, yet it remains rather controversial and very hard to assess homogenously at the scale of the entire continent. The three earthquake source models are characterised by alternative options to calculate and spatially distribute future seismic activity (Fig.…”

Section: Modelling Maximum Magnitudesmentioning

confidence: 99%

The 2013 European Seismic Hazard Model: key components and results

Woessner

Danciu

Giardini

et al. 2015

Bull Earthquake Eng

486

330

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The 2013 European Seismic Hazard Model (ESHM13) results from a community-based probabilistic seismic hazard assessment supported by the EU-FP7 project "Seismic Hazard Harmonization in Europe" (SHARE, 2009(SHARE, -2013. The ESHM13 is a consistent seismic hazard model for Europe and Turkey which overcomes the limitation of national borders and includes a through quantification of the uncertainties. It is the first completed regional effort contributing to the "Global Earthquake Model" initiative. It might serve as a reference model for various applications, from earthquake preparedness to earthquake risk mitigation strategies, including the update of the European seismic regulations for building design (Eurocode 8), and thus it is useful for future safety assessment and improvement of private and public buildings. Although its results constitute a reference for Europe, they do not replace the existing national design regulations that are in place for seismic design and construction of buildings. The ESHM13 represents a significant improvement compared to previous efforts as it is based on (1) the compilation of updated and harmonised versions of the databases required for probabilistic seismic hazard assessment, (2) the adoption of standard procedures and robust methods, especially for expert elicitation and consensus building among hundreds of European experts, (3) the multi-disciplinary input from all branches of earthquake science and engineering, (4) the direct involvement of the CEN/TC250/SC8 committee in defining output specifications relevant for Eurocode 8 and (5)

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“…They concluded that this subsegment might be locked and thus represents a potential nucleation point for an impending Marmara earthquake. This view is also supported by Global Positioning System data (Ergintav et al, 2014).…”

Section: Tectonic Setting and The Gonaf Projectmentioning

confidence: 81%

Seismic‐Wave Propagation in Shallow Layers at the GONAF‐Tuzla Site, Istanbul, Turkey

Raub

Bohnhoff

Petrović

et al. 2016

Bulletin of the Seismological Society of America

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Using the first dataset available from the downhole Geophysical Observatory of the North Anatolian Fault, we investigated near-surface seismic-wave propagation on the Tuzla Peninsula, Istanbul, Turkey. We selected a dataset of 26 seismograms recorded at Tuzla at sensor depths of 0, 71, 144, 215, and 288 m. To determine near-surface velocities and attenuation structures, the waveforms from all sensors were pairwise deconvolved and stacked. This produced low-noise empirical Green's functions for each borehole depth interval. From the Green's functions, we identified reflections from the free surface and a low-velocity layer between ∼90 and ∼140 m depth. The presence of a low-velocity zone was also confirmed by a sonic log run in the borehole. This structure, plus high near-surface P-and S-wave velocities of ∼3600-4100 and ∼1800 m=s, lead to complex interference effects between upgoing and downgoing waves. As a result, the determination of quality factors (Q) with standard spectral ratio techniques was not possible. Instead, we forward modeled the Green's functions in the time domain to determine effective Q values and to refine our velocity estimates. The effective Q P values for the depth intervals of 0-71, 0-144, 0-215, and 0-288 m were found to be 19, 35, 39, and 42, respectively. For the S waves, we obtained an effective Q S of 20 in the depth interval of 0-288 m. Considering the assumptions made in our modeling approach, it is evident that these effective quality factors are biased by impedance contrasts between our observation points. Our results show that, even after correcting for a free-surface factor of 2, the motion at the surface was found to be 1.7 times greater than that at 71 m depth. Our efforts also illustrate some of the difficulties of dealing with site effects in a strongly heterogeneous subsurface.Online Material: Plots of resistivity and caliper logs and the spectra of all 26 events.

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Istanbul's earthquake hot spots: Geodetic constraints on strain accumulation along faults in the Marmara seismic gap

Cited by 150 publications

References 25 publications

No significant steady state surface creep along the North Anatolian Fault offshore Istanbul: Results of 6 months of seafloor acoustic ranging

No significant steady state surface creep along the North Anatolian Fault offshore Istanbul: Results of 6 months of seafloor acoustic ranging

The 2013 European Seismic Hazard Model: key components and results

Seismic‐Wave Propagation in Shallow Layers at the GONAF‐Tuzla Site, Istanbul, Turkey

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