[GONAF] GONAF - A deep Geophysical Observatory at the North Anatolian Fault

Climate & Ecosystems

Year of Application: 2010

Expedition ID: 5039

Current Status: ongoing

active faulting
borehole observatory
earthquake physics
high-resolutionseismic monitoring
northern anatolian fault zone
seismic hazards
Master Data

Prof. Dr. Jochen Zschau (PI)
Prof. Dr. Joerg Erzinger (PI)
Prof. Dr. Georg Dresen (PI)
Dr. Christoph Janssen (PI)
Dr. Fatih Bulut (PI)
Prof. Dr. Marco Bohnhoff (PI)
Dr. Oliver Heidbach (PI)
Prof. Dr. Stefano Parolai (PI)

Bernhard Prevedel (OSG)
Jochem Kück (OSG)
Dr. Simona Pierdominici (Scientific Participant)
Dr. Michele Ickrath (Scientific Participant)
Dr. Digdem Acarel (Scientific Participant)
Dr. Ludger Küperkoch (Scientific Participant)
Prof. Dr. Jan Behrmann (Scientific Participant)
Dr. Bita Najdahmadi (Scientific Participant)
Dr. Christina Raub (Scientific Participant)
Dr. Raymond Jonckheere (Scientific Participant)
Dr. Heiko Woith (Workshop Participant)
Christopher Wollin (Workshop Participant)
Dr. Eva Stierle (Workshop Participant)
Dr. Rongjiang Wang (Workshop Participant)

Geologisches Alter: quarternary

Latitude: 40°52'32''N


Regionen & Städte:

Marmara Sea
Prince Islands
North Anatolian Fault

Longitude: 28°58'18''E



hard rock

Drilling Data

Drilling Depth: 1700.0
Core Yield:
Core Length:
Amount of Drill Holes: 5
Amount of Drill Locations: 5

Core Length-Drill Depth-Ratio:
Core Yield-Core Length-Ratio:


We propose a borehole observatory consisting of two 500 m deep vertical boreholes at the offshore part of the NAFZ along the Princes Islands segment that includes the transition between the 1999 Izmit rupture and the current seismic gap (GONAF - Geophysical Observatory at the North Anatolian Fault). The principal scientific objective is to study physical processes acting before, during and after the expected M>7 earthquake along the Princes Islands segment of the NAFZ by monitoring microseismic activity at significantly reduced magnitude detection threshold and improved hypocentral resolution. It is also intended to study wave propagation characteristics of a large earthquake using downhole seismic recordings at two different spots along the expected rupture and potentially close to its initiation point. The North Anatolian Fault Zone (NAFZ) has produced a series of large and devastating earthquakes during the 20th century starting in 1939 in eastern Anatolia and then systematically propagating westwards. The Sea of Marmara today represents a seismic gap of up to 150 km length and this part of the NAFZ is the only segment that has not been activated in the present series. Owing to post-seismic stress redistribution after the 1999 Izmit earthquake the eastern part of the seismic gap along the Princes Islands segment is likely subjected to enhanced stresses. The suggested borehole locations are on two of the Princes Islands in direct vicinity to the major branch of the fault zone and the mega-city of Istanbul. The location of the observatory is unique representing the only possible long-term monitoring sites along the NAFZ segment below the Sea of Marmara and the city of Istanbul in an onshore location. GONAF is focussed on the installation of a deep borehole seismological observatory. Combining GONAF recordings with existing nearby surface arrays and regional permanent stations will allow to substantially improve monitoring conditions along the entire Princes Islands segment by lowering the magnitude-detection threshold by at least one order of magnitude thus allowing to study the spatial and temporal evolution of microseismic activity prior to the expected Marmara earthquake with unprecedented detail. Prior to the long-term installation of the seismological observatory we will use the GONAF boreholes to also measure heat and gas/fluid flow and to determine orientation and magnitude of local stresses for the first time in the entire Marmara region.

Related Publications

Geli, L., Henry, P., Grall, C., Tary, J.-B., Lomax, A., Batsi, E., Riboulot, V., Cros, E., Gürbüz, C., Isik, S.E., Sengör, A.M.C., Le Pichon, X., Ruffine, L., Dupre, S., Thomas, Y., Kalafat, D., Bayrakci, G., Coutellier, Q., Regnier, T., Westbrook, G., Saritas, H., Cifi, G., Cagatay, M.N., Özeren, M.S., Görür, N., Tryon, M., Bohnhoff, M., Gasperini, L., Klingelhoefer, F., Scalabrin, C., Augustin, J.-M., Embriaco, D., Marinato, G, Frugoni, F., Monna, S., Etiope, G., Favali, P., Becel, A. (2018). "Gas and seismicity within the Istanbul seismic gap" Scientific Reports 8

Najdahmadi, Bita, Hrubcová, Pavla, Vavryčuk, Václav, Bohnhoff, Marco (2018). "Imaging the Mudurnu Segment of the North Anatolian Fault Zone From Waveforms of Small Earthquakes" Journal of Geophysical Research: Solid Earth p493-512

Raub, Christina (2017). "Characterizing Near-Surface Velocity and Attenuation Structures And Evaluating Spatiotemporal b-Value Variations in the Marmara Sea Region" Dissertation

Bohnhoff, M., Dresen, G., Ceken, U., Kadirioglu, F. T., Kartal, R. F., Kilic, T., Nurlu, M., Yanik, K., Acarel, D., Bulut, F., Ito, H., Johnson, W., Malin, P. E., Mencin, D. (2017). "GONAF – the borehole Geophysical Observatory at the North Anatolian Fault in the eastern Sea of Marmara" Sci. Dril. 22 p19-28

Najdahmadi, B., (2017). "Imaging the North Anatolian Fault Zone with Fault Zone Head Waves, Reflected and Converted Phases."

Bohnhoff, Marco, Wollin, Christopher, Domigall, Dorina, Küperkoch, Ludger, Martínez-Garzón, Patricia, Kwiatek, Grzegorz, Dresen, Georg, Malin, Peter E. (2017). "Repeating Marmara Sea earthquakes: indication for fault creep" Geophysical Journal International 210 p332-339

Raub, Christina, Martínez-Garzón, Patricia, Kwiatek, Grzegorz, Bohnhoff, Marco, Dresen, Georg (2017). "Variations of seismic b-value at different stages of the seismic cycle along the North Anatolian Fault Zone in northwestern Turkey" Tectonophysics 712-713 p232-248

Najdahmadi, B., Bohnhoff, M., Ben-Zion, Y. (2016). "Bimaterial interfaces at the Karadere segment of the North Anatolian Fault, northwestern Turkey" Journal of Geophysical Research: Solid Earth 121 p931-950

Bohnhoff, Marco, Martínez-Garzón, Patricia, Bulut, Fatih, Stierle, Eva, Ben-Zion, Yehuda (2016). "Maximum earthquake magnitudes along different sections of the North Anatolian fault zone" Tectonophysics 674 p147-165

Raub, Christina, Bohnhoff, Marco, Petrovic, Bojana, Parolai, Stefano, Malin, Peter, Yanik, Kenan, Kartal, Recai Feyiz, Kiliç, Tuğbay (2016). "Seismic‐Wave Propagation in Shallow Layers at the GONAF‐Tuzla Site, Istanbul, Turkey" Bulletin of the Seismological Society of America 106 p912-927

Acarel, Digdem (2015). "Characterization of the Crustal Velocity Field in Space and Time Using Ambient Seismic Noise" Dissertation

Ickrath, Michèle, Bohnhoff, Marco, Dresen, Georg, Martínez-Garzón, Patricia, Bulut, Fatih, Kwiatek, Grzegorz, Germer, Oliver (2015). "Detailed analysis of spatiotemporal variations of the stress field orientation along the Izmit-Düzce rupture in NW Turkey from inversion of first-motion polarity data" Geophysical Journal International 202 p2120-2132

Prevedel, Bernhard, Bulut, Fatih, Bohnhoff, Marco, Raub, Christina, Kartal, Recai F., Alver, Fatih, Malin, Peter E. (2015). "Downhole geophysical observatories: best installation practices and a case history from Turkey" International Journal of Earth Sciences 104 p1537-1547

Stierle, Eva (2015). "Non-Double-Couple Components in Moment Tensors of Aftershock Seismicity and Laboratory Earthquakes" Dissertation

Ickrath, Michèle (2015). "Spatiotemporal variations of the local stress field and fault asperities at the North Anatolian Fault in NW Turkey analysed based on microseismic recordings" Dissertation

Acarel, Diğdem, Bulut, Fatih, Bohnhoff, Marco (2014). "Ambient Noise Analysis in the Eastern Sea of Marmara Region in Northwest Turkey: Lateral Variations of the Crustal Velocity Field" Bulletin of the Seismological Society of America 104 p1954-1963

Acarel, Diğdem, Bulut, Fatih, Bohnhoff, Marco, Kartal, Recai (2014). "Coseismic velocity change associated with the 2011 Van earthquake (M7.1): Crustal response to a major event" Geophysical Research Letters p4519-4526

Stierle, Eva, Vavryčuk, Vaclav, Šílený, Jan, Bohnhoff, Marco (2014). "Resolution of non-double-couple components in the seismic moment tensor using regional networks—I: a synthetic case study" Geophysical Journal International p1869-1877

Stierle, Eva, Bohnhoff, Marco, Vavryčuk, Václav (2014). "Resolution of non-double-couple components in the seismic moment tensor using regional networks—II: application to aftershocks of the 1999 Mw 7.4 Izmit earthquake" Geophysical Journal International p1878-1888

Ickrath, M., Bohnhoff, M., Bulut, F., Dresen, G. (2014). "Stress rotation and recovery in conjunction with the 1999 Izmit Mw 7.4 earthquake" Geophysical Journal International p951-956

Bohnhoff, Marco, Bulut, Fatih, Dresen, Georg, Malin, Peter E., Eken, Tuna, Aktar, Mustafa (2013). "An earthquake gap south of Istanbul" Nature Communications 4 p1999

Eken, Tuna, Bohnhoff, Marco, Bulut, Fatih, Can, Birsen, Aktar, Mustafa (2013). "Crustal anisotropy in the eastern Sea of Marmara region in northwestern Turkey" Bulletin of the Seismological Society of America 103 p911-924

Bulut, Fatih, Ben-Zion, Yehuda, Bohnhoff, Marco (2012). "Evidence for a bimaterial interface along the Mudurnu segment of the North Anatolian Fault Zone from polarization analysis of P waves" Earth and Planetary Science Letters 327-328 p17-22

Hurd, Owen, Bohnhoff, Marco (2012). "Stress‐and Structure‐Induced Shear‐Wave Anisotropy along the 1999 Izmit Rupture, Northwest Turkey" Bulletin of the Seismological Society of America 102 p2177-2188

Bulut, Fatih, Ellsworth, William L, Bohnhoff, Marco, Aktar, Mustafa, Dresen, Georg (2011). "Spatiotemporal earthquake clusters along the North Anatolian fault zone offshore İstanbul" Bulletin of the Seismological Society of America 101 p1759-1768

Bohnhoff, Marco, Bulut, Fatih, Aktar, Mustafa, Dresen, Georg (2011). "System Erde : Schwerpunkt Naturgefahren und Frühwarnsysteme" System Erde (GFZ) Jahrgang 1, Heft 1

Görgün, E., Bohnhoff, M., Bulut, F., Dresen, G. (2010). "Seismotectonic setting of the Karadere–Düzce branch of the North Anatolian Fault Zone between the 1999 Izmit and Düzce ruptures from analysis of Izmit aftershock focal mechanisms" Tectonophysics 482 p170-181

Hergert, Tobias, Heidbach, Oliver (2010). "Slip-rate variability and distributed deformation in the Marmara Sea fault system" Nature Geoscience 3 p132

Görgün, Ethem, Zang, Arno, Bohnhoff, Marco, Milkereit, Claus, Dresen, Georg (2009). "Analysis of Izmit aftershocks 25 days before the November 12th 1999 Düzce earthquake, Turkey" Tectonophysics 474 p507-515

Bulut, Fatih, Bohnhoff, Marco, Ellsworth, William L., Aktar, Mustafa, Dresen, Georg (2009). "Microseismicity at the North Anatolian Fault in the Sea of Marmara offshore Istanbul, NW Turkey" Journal of Geophysical Research: Solid Earth 114 pB09302

Bohnhoff, Marco, Dresen, Georg, Ellsworth, William L, Ito, Hisao (2009). "Passive seismic monitoring of natural and induced earthquakes: case studies, future directions and socio-economic relevance" New Frontiers in Integrated Solid Earth Sciences p261-285

Janssen, C, Bohnhoff, M, Vapnik, Y, Görgün, E, Bulut, F, Plessen, B, Pohl, D, Aktar, M, Okay, AI, Dresen, G (2009). "Tectonic evolution of the Ganos segment of the North Anatolian Fault (NW Turkey)" Journal of Structural Geology 31 p11-28

Dresen, G., Bohnhoff, M., Aktar, M., Eyidogan, H. (2008). "Drilling the North Anatolian Fault (Workshop Report)" Scientific Drilling 6 p58-59

Bohnhoff, M, Bulut, F, Görgün, E, Milkereit, C, Dresen, G (2008). "Seismotectonic setting at the North Anatolian Fault Zone after the 1999 Mw= 7.4 Izmit earthquake based on high-resolution aftershock locations" Advances in Geosciences 14 p85-92

Bulut, Fatih, Aktar, Mustafa (2007). "Accurate relocation of İzmit earthquake (Mw = 7.4, 1999) aftershocks in Çınarcık Basin using double difference method" Geophysical Research Letters 34 pL10307

Boztuğ, Durmuş, Jonckheere, Raymond C. (2007). "Apatite fission track data from central Anatolian granitoids (Turkey): Constraints on Neo-Tethyan closure" Tectonics 26 pTC3011

Bulut, Fatih, Bohnhoff, Marco, Aktar, Mustafa, Dresen, Georg (2007). "Characterization of aftershock-fault plane orientations of the 1999 İzmit (Turkey) earthquake using high-resolution aftershock locations" Geophysical Research Letters 34 pL20306

Dresen, G., Bohnhoff, M., Aktar, M., Eyidogan, H. (2007). "Drilling the North Anatolian Fault" Sci. Dril. Special Issue No. 1 p42-44

Tobin, Harold, Ito, Hisao, Behrmann, Jan Hinrich, Hickman, Stephen, Kimura, Gaku (2007). "IODP-ICDP Workshop examines challenges of fault zone drilling" Scientific Drilling 1 p5-16

Bohnhoff, Marco, Grosser, Helmut, Dresen, Georg (2006). "Strain partitioning and stress rotation at the North Anatolian fault zone from aftershock focal mechanisms of the 1999 Izmit Mw= 7.4 earthquake" Geophysical Journal International 166 p373-385

Boztuğ, D., Jonckheere, R., Wagner, G. A., Yeğingil, Z. (2004). "Slow Senonian and fast Palaeocene–Early Eocene uplift of the granitoids in the Central Eastern Pontides, Turkey: apatite fission-track results" Tectonophysics 382 p213-228