yyufbed Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi 1300-5413 2667-467X Van Yüzüncü Yıl Üniversitesi 10.53433/yyufbed.1793064 Seismology Sismoloji Tendürek Volkanı (Doğu Türkiye) Civarındaki Mikrodepremlerin Kökeninin Odak Mekanizması Çözümleri ve Gerilme Değişimi ile Araştırılması Investigating the Origin of Microearthquakes around Tendürek Volcano (Eastern Türkiye) using Focal Mechanism Solutions and Stress Changes https://orcid.org/0009-0006-4238-7145 Alkan Ayşegül VAN YUZUNCU YIL UNIVERSITY https://orcid.org/0000-0002-7682-962X Akkaya İsmail VAN YUZUNCU YIL UNIVERSITY https://orcid.org/0000-0003-3912-7503 Alkan Hamdi Van Yüzüncü Yıl University 04 29 2026 31 108 125 09 29 2025 02 10 2026 Copyright © 1995, Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi 1995 Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi

Tendürek Volkanı, Doğu Anadolu’da yer alan Kuvaterner yaşlı volkanik kütlelerden biridir. Volkanik etkinliği, Geç Miyosen’den itibaren bölgesel tektonik süreçler tarafından doğrudan kontrol edilmiştir. Tendürek Volkanı ve çevresinde, normal bileşenli Tendürek Fayı ile doğrultu atımlı bileşene sahip Balıkgölü Fay Zonu gibi çeşitli tektonik yapılar bulunmaktadır. Bu faylar ve volkan, bölgedeki yerel depremselliğin oluşumundan sorumlu olabilecek yapısal birimlerdir. Bu çalışmada, Tendürek Volkanı civarında meydana gelen 22 adet düşük magnitüdlü (ML ≤ 2.6) deprem seçilerek bölgesel depremselliğin kaynağını belirlemek ve yorumlamak amaçlanmıştır. Seçilen depremlerin odak mekanizması çözümleri FPFIT ve PINV algoritmaları kullanılarak hesaplanmış, ayrıca farklı derinliklerde Coulomb gerilme değişimleri belirlenmiştir. Elde edilen sonuçlar, odak mekanizması çözümleri ve Coulomb gerilme modelleriyle birlikte değerlendirildiğinde, volkanın altındaki sığ seviyelerde pozitif gerilme değerlerinin yoğunlaştığı ve bu değerlerin çalışma alanının batı ve kuzeydoğu kesimlerine doğru yayıldığı görülmüştür. Sonuç olarak, bu bulgular volkanik ortamın yapısal özelliklerinin ve yerel tektoniklerle etkileşiminin anlaşılmasına önemli katkılar sağlamaktadır.

Tendürek Volcano is one of the Quaternary volcanic edifices in Eastern Anatolia. Its volcanic activity has been directly controlled by active regional tectonics since the Late Miocene. In and around Tendürek Volcano, several tectonic units are present, including the Tendürek Fault with a normal fault component and the Balıkgölü Fault Zone with a strike-slip fault component. Both the faults and the volcano are capable of generating local seismicity in the region. In this study, 22 low-magnitude seismic events (ML ≤ 2.6) that occurred around Tendürek Volcano were selected to identify and interpret the source of regional seismicity. Focal mechanism solutions for these events were determined using the FPFIT and PINV algorithms, and Coulomb stress changes were calculated from the focal mechanism solutions at different depths. The results, integrated with focal mechanism solutions and Coulomb stress modeling, indicate that positive stress values are concentrated beneath the volcano at shallow depths and extend westward and northeastward across the study area. Ultimately, these findings provide crucial insights into the structural characteristics of the volcanic environment and its interaction with local tectonics.

 Tendürek Volcano Focal Mechanism Stress Change Seismicity Tendürek Volkanı Odak Mekanizması Gerilme Değişimi Depremsellik AFAD. (2025). Disaster and Emergency Management Authority. Erişim tarihi: 25.08.2025. https://deprem.afad.gov.tr/event-catalog Akın, U., Ulugergerli, E. U., & Kutlu, S. (2014). The assessment of geothermal potential of Turkey by means of heat flow estimation. Bulletin of the Mineral Research and Exploration, 149(149), 201-210. https://doi.org/10.19111/bmre.58938 Alkan, H. (2022). Crustal structure in and around the East Anatolian volcanic belt by using receiver functions stacking. Journal of African Earth Sciences, 191, 104532. https://doi.org/10.1016/j.jafrearsci.2022.104532 Alkan, H., & Bayrak, E. (2022). Coulomb stress changes and magnitude-frequency distribution for Lake Van region. Bulletin of the Mineral Research and Exploration, 168(168), 141-156. https://doi.org/10.19111/bulletinofmre.990666 Alkan, H., Öztürk, S., & Akkaya, İ. (2023). Seismic Hazard Implications in and Around the Yedisu Seismic Gap (Eastern Türkiye) Based on Coulomb Stress Changes, b-Values, and S-wave Velocity, Pure and Applied Geophysics, 180 (9), 3227-3248. Alkan, H., Büyüksaraç, A., & Bektaş, Ö. (2024). Investigation of earthquake sequence and stress transfer in the Eastern Anatolia Fault Zone by Coulomb stress analysis. Turkish Journal of Earth Sciences, 33(1), 56-68. https://doi.org/10.55730/1300-0985.1898 Alkan, A. (2026). Investigation of Coulomb Stress Changes of Microearthquakes in the vicinity of Tendürek Volcano using Focal Mechanism Solutions. (MSc), Yuzuncu Yıl University, Institute of Natural and Applied Science, Van, Turkey. Asayesh, B. M., Zafarani, H., & Tatar, M. (2020). Coulomb stress changes and secondary stress triggering during the 2003 (Mw 6.6) Bam (Iran) earthquake. Tectonophysics, 775, 228304. https://doi.org/10.1016/j.tecto.2019.228304 Bathke, H., Sudhaus, H., Holohan, E. P., Walter, T. R., & Shirzaei, M. (2013). An active ring fault detected at Tendürek volcano by using InSAR. Journal of Geophysical Research: Solid Earth, 118(8), 4488-4502. https://doi.org/10.1002/jgrb.50305 Bathke, H., Nikkhoo, M., Holohan, E. P., & Walter, T. R. (2015). Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data. Earth and Planetary Science Letters, 422, 157 168. https://doi.org/10.1016/j.epsl.2015.03.041 Bektaş, Ö., Ravat, D., Büyüksaraç, A., Bilim, F., & Ateş, A. (2007). Regional geothermal characterisation of East Anatolia from aeromagnetic, heat flow and gravity data. Pure and Applied Geophysics, 164(5), 975-998. https://doi.org/10.1007/s00024-007-0196-5 Bektaş, Ö., Alkan, H., Pırtı, A., Yücel, M., & Büyüksaraç, A. (2025). Stress accumulation on the Karlıova (Bingöl) Triple Junction after two big earthquakes (Pazarcık-Ekinözü) in Turkey in 2023. Bulletin of Geophysics and Oceanography, 66(2). https://doi.org/10.4430/bgo00485 Büyüksaraç, A., Bektaş, Ö., & Alkan, H. (2024). Fault modeling around southern Anatolia using the aftershock sequence of the Kahramanmaraş earthquakes (Mw= 7.7 and Mw= 7.6) and an interpretation of potential field data. Acta Geophysica, 72(5), 2985-2996. https://doi.org/10.1007/s11600-023-01192-4 Cailleau, B., LaFemina, P. C., & Dixon, T. H. (2007). Stress accumulation between volcanoes: an explanation for intra-arc earthquakes in Nicaragua?. Geophysical Journal International, 169(3), 1132-1138. https://doi.org/10.1111/j.1365-246X.2007.03353.x Chen, F., Diao, F., Xu, Y., & Xiong, X. (2024) Low‐viscosity zones beneath the Coso Volcanic Field revealed by postseismic deformations following the 2019 Ridgecrest earthquake. Geophysical Research Letters, 51, e2024GL109566. https://doi.org/10.1029/2024GL109566 Dhar, S., Takada, Y., & Muto, J. (2025). Inferring 3‐D rheology of low‐viscosity zone around quaternary volcanoes of NE Japan from postseismic deformation of the 2011 Tohoku‐Oki earthquake. Journal of Geophysical Research: Solid Earth, 130, e2024JB029939. https://doi.org/10.1029/2024JB029939 Emre, Ö., Duman, T. Y., Özalp, S., Şaroğlu, F., Olgun, Ş., Elmacı, H., & Çan, T. (2018). Active fault database of Turkey. Bulletin of Earthquake Engineering, 16(8), 3229-3275. https://doi.org/10.1007/s10518-016-0041-2 Ercan, T., Fujitami, T., Madsuda, J. L., Notsu, K., & Ui, T. (1990). Doğu ve Güneydoğu Anadolu Neojen-Kuvaterner volkanitlerine ilişkin yeni jeokjmyasal, radyometrik ve izotopik verilerin yorumu. Maden Tetkik ve Arama Dergisi, 110(110). Feuillet, N., Cocco, M., Musumeci, C., & Nostro, C. (2006). Stress interaction between seismic and volcanic activity at Mt Etna. Geophysical Journal International, 164(3), 697-718. https://doi.org/10.1111/j.1365-246X.2005.02824.x Foulger, G. R., Julian, B. R., Hill, D. P., Pitt, A. M., Marlin, P. E., & Shalev, E., (2004), Non-double-couple microearthquakes at Long Valley caldera, California, provide evidence for hydraulic fracturing, Journal of Volcanol. Geoth. Res., 132(45-71). Gargani, J., Geoffroy, L., Gac, S., & Cravoisier, S. (2006). Fault slip and Coulomb stress variations around a pressured magma reservoir: consequences on seismicity and magma intrusion. Terra Nova, 18(6), 403-411. https://doi.org/10.1111/j.1365-3121.2006.00705.x Gudmundsson, A., Marti, J., & Turon, E. (1997). Stress fields generating ring faults in volcanoes. Geophysical research letters, 24(13), 1559-1562. https://doi.org/10.1029/97GL01494 Gülyüz, E., Durak, H., Özkaptan, M., & Krijgsman, W. (2020). Paleomagnetic constraints on the early Miocene closure of the southern Neo-Tethys (Van region; East Anatolia): Inferences for the timing of Eurasia-Arabia collision. Global and Planetary Change, 185, 103089. https://doi.org/10.1016/j.gloplacha.2019.103089 Gündüz, H. İ., Yılmaztürk, F., & Orhan, O. (2023). An investigation of volcanic ground deformation using InSAR observations at Tendürek Volcano (Turkey). Applied Sciences, 13(11), 6787. https://doi.org/10.3390/app13116787 Gündüz, H. İ. (2024). Türkiye’deki aktif volkanlarda meydana gelen yüzey deformasyonlarının jeodezik tekniklerle izlenmesi. (PhD), Aksaray University, Institute of Natural and Applied Science, Aksaray. Hardebeck, J. L., & Shearer, P. M. (2002). A new method for determining first-motion focal mechanisms. Bulletin of the Seismological Society of America, 92(6), 2264-2276. https://doi.org/10.1785/0120010200 Helffrich, G., Wookey, J., & Bastow, I. (2013). The Seismic Analysis Code. A Primer and User’s Guide (Cambridge, United Kingdom). Karakhanian, A., Djrbashian, R., Trifonov, V., Philip, H., Arakelian, S., & Avagian, A. (2002). Holocene-historical volcanism and active faults as natural risk factors for Armenia and adjacent countries. Journal of Volcanology and Geothermal Research, 113(1-2), 319-344. https://doi.org/10.1016/S0377-0273(01)00264-5 Kearney, R. J., Goff, J., Smith, V., Schwab, M. J., Özdemir, Y., Karaoǧlu, Ö., ... & Brauer, A. (2025). Glass geochemistry and tephrostratigraphy of key tephra layers in and around Lake Van, Eastern Anatolian Volcanic Province (EAVP). Quaternary Science Reviews, 352, 109165. https://doi.org/10.1016/j.quascirev.2024.109165 Keskin, M. (2003). Magma generation by slab steepening and breakoff beneath a subduction‐accretion complex: An alternative model for collision‐related volcanism in Eastern Anatolia, Turkey. Geophysical research letters, 30(24). https://doi.org/10.1029/2003GL018019 Kiyak, A., Pamuk, E., Köksal, S., Bakar, M. L., & Tosuner, S. (2023). New high resolution aeromagnetic anomaly map of Türkiye and its various derivative-based maps. Turkish Journal of Earth Sciences, 32(2), 231-247. https://doi.org/10.55730/1300-0985.1840 Kilb, D., & Hardebeck, J. L. (2006). Fault parameter constraints using relocated earthquakes: a validation of first motion focal-mechanism data. Bulletin of the Seismological Society of America, 96(3), 1140-1158. https://doi.org/10.1785/0120040239 King, G. C., Stein, R. S., & Lin, J. (1994). Static stress changes and the triggering of earthquakes. Bulletin of the Seismological Society of America, 84(3), 935-953. https://doi.org/10.1785/BSSA0840030935 Koçyiğit, A., Yilmaz, A., Adamia, S., & Kuloshvili, S. (2001). Neotectonics of East Anatolian Plateau (Turkey) and Lesser Caucasus: implication for transition from thrusting to strike-slip faulting. Geodinamica Acta, 14(1-3), 177-195. https://doi.org/10.1080/09853111.2001.11432443 Lebedev, V. A., Sharkov, E. V., Ünal, E., & Keskin, M. (2016a). Late Pleistocene Tendürek volcano (Eastern Anatolia, Turkey): I. Geochronology and petrographic characteristics of igneous rocks. Petrology, 24(2), 127-152. https://doi.org/10.1134/S0869591116020041 Lebedev, V. A., Chugaev, A. V., Ünal, E., Sharkov, E. V., & Keskin, M. (2016b). Late pleistocene tendürek volcano (eastern Anatolia, Turkey). II. Geochemistry and petrogenesis of the rocks. Petrology, 24(3), 234-270. https://doi.org/10.1134/S0869591116030048 Lin, L. C. J., Chuang, R. Y., & Nishimura, T. (2025). Exploring Coulomb stress changes on active structures in Taiwan inferred from decadal GNSS observations. Earth, Planets and Space, 77(1), 88. https://doi.org/10.1186/s40623-025 02215-8 Massa, B., D'Auria, L., Cristiano, E., & De Matteo, A. (2016). Determining the stress field in active volcanoes using focal mechanisms. Frontiers in Earth Science, 4, 103. https://doi.org/10.3389/feart.2016.00103 Miller, C. A., Le Mével, H., Currenti, G., Williams‐Jones, G., & Tikoff, B. (2017). Microgravity changes at the Laguna del Maule volcanic field: Magma‐induced stress changes facilitate mass addition. Journal of Geophysical Research: Solid Earth, 122(4), 3179-3196. https://doi.org/10.1002/2017JB014048 Ottemöller, L., Voss, P.H. and Havskov J. (2021). SEISAN Earthquake Analysis Software for Windows, Solaris, Linux and Macosx, Version 12.0. 607 pp. University of Bergen. ISBN 978-82-8088-501-2, URL http://seisan.info. Özdemir, Y., Karaoğlu, Ö., Tolluoğlu, A. Ü., & Güleç, N. (2006). Volcanostratigraphy and petrogenesis of the Nemrut stratovolcano (East Anatolian High Plateau): the most recent post-collisional volcanism in Turkey. Chemical geology, 226(3-4), 189-211. https://doi.org/10.1016/j.chemgeo.2005.09.020 Özdemir, Y., Mercan, Ç., Oyan, V., & Özdemir, A. A. (2019). Composition, pressure, and temperature of the mantle source region of quaternary nepheline-basanitic lavas in Bitlis Massif, Eastern Anatolia, Turkey: A consequence of melts from Arabian lithospheric mantle. Lithos, 328, 115-129. https://doi.org/10.1016/j.lithos.2019.01.020 Öztürk, S. (2017). Space-time assessing of the earthquake potential in recent years in the Eastern Anatolia region of Turkey. Earth Sciences Research Journal, 21(2), 67-75. https://doi.org/10.15446/esrj.v21n2.50889 Öztürk, S. (2018). Earthquake hazard potential in the Eastern Anatolian Region of Turkey: seismotectonic b and Dc values and precursory quiescence Z-value. Frontiers of Earth Science, 12(1), 215-236. https://doi.org/10.1007/s11707 017-0642-3 Öztürk, S., & Alkan, H. (2023). Multiple parameter analysis for assessing and forecasting earthquake hazards in the Lake Van region, Turkey. Baltica, 36. https://hdl.handle.net/20.500.12440/6116 Pearce, J. A., Bender, J. F., De Long, S. E., Kidd, W. S. F., Low, P. J., Güner, Y., Şaroğlu, F., Yılmaz, Y., Moorbath, S., Mitchell, J. J. (1990). Genesis of collision volcanism in eastern Anatolia Turkey. J. Volcanol. Geotherm. Res., 44: 189-229. https://doi.org/10.1016/0377-0273(90)90018-B Reasenberg, P., & Oppenheimer, D. (1986). FPFIT, FPPLOT and FPPAGE: Fortran computer programs for calculating and displaying earthquake fault-plane solutions (Vol. 85, No. 739). US Geological Survey. https://doi.org/10.3133/ofr85739 Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, S., Cakmak, R., et al. (2006). GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions. Journal of Geophysical Research, 111(B5), B05411. https://doi.org/10.1029/2005JB004051 Snoke, J.A. (2003). 85.12 FOCMEC: FOCal MEChanism determinations. International Geophysics Series, 81, 1629-1630. Suetsugu, D. (1998). Practice on source mechanism, iisee lecture note, Technical report, Tsukuba, Japan. Şen, P. A., Temel, A., & Gourgaud, A. (2004). Petrogenetic modelling of Quaternary post-collisional volcanism: a case study of central and eastern Anatolia. Geological Magazine, 141(1), 81-98. https://doi.org/10.1017/S0016756803008550 Şengör, A. C., & Yilmaz, Y. (1981). Tethyan evolution of Turkey: a plate tectonic approach. Tectonophysics, 75(3-4), 181-241. https://doi.org/10.1016/0040-1951(81)90275-4 Şengör, A. M. C., Özeren, S., Genç, T., & Zor, E. (2003). East Anatolian high plateau as a mantle‐supported, north south shortened domal structure. Geophysical Research Letters, 30(24). https://doi.org/10.1029/2003GL017858 Şengör, A. M. C., Tüysüz, O., İmren, C., Sakınç, M., Eyidoğan, H., Görür, N., Pichon, X. L., Rangin, C., Parsons, B., & Tok, B. (2005). The North Anatolian Fault: A new look. Annual Review of Earth and Planetary Sciences, 33(1), 37–112. https://doi.org/10.1146/annurev.earth.32.101802.120415 Şengör, A. C., Özeren, M. S., Keskin, M., Sakınç, M., Özbakır, A. D., & Kayan, İ. (2008). Eastern Turkish high plateau as a small Turkic-type orogen: Implications for post-collisional crust-forming processes in Turkic-type orogens. Earth Science Reviews, 90(1-2), 1-48. https://doi.org/10.1016/j.earscirev.2008.05.002 Tahir, M., Ahmad, Z., Sabahat, S., Mushtaq, M. N., Iqbal, T., Shah, M. A., & Aftab, A. (2024). Source parameters and aftershock pattern of the October 7, 2021, M5.9 Harnai earthquake, Pakistan. Earthquake Science, 37(4), 304-323. https://doi.org/10.1016/j.eqs.2024.04.007 Tilling, R. I., & Dvorak, J.J., (1993) Anatomy of a basaltic volcano, Nature, 363(125-132). Toda, S., Stein, R., & Sagiya, T., (2002). Evidence from the AD 2000 Izu islands earthquake swarm that stressing rate governs seismicity, Nature, 419(58-61). Toda, S., Stein, R. S., Sevilgen, V., & Lin, J. (2011). Coulomb 3.3 Graphic-rich deformation and stress-change software for earthquake, tectonic, and volcano research and teaching—user guide. US Geological Survey open-file report, 1060(2011), 63. https://pubs.usgs.gov/of/2011/1060 Troise, C., Pingue, F., & De Natale, G. (2003) Coulomb stress changes at calderas: Modeling the seismicity of Campi Flegrei (southern Italy), Journal of Geophysical Research: Solid Earth, 108, B6. https://doi.org/10.1029/2002JB002006 Ulusoy, İ. (2016). Temporal radiative heat flux estimation and alteration mapping of Tendürek volcano (eastern Turkey) using ASTER imagery. Journal of Volcanology and Geothermal Research, 327, 40-54. https://doi.org/10.1016/j.jvolgeores.2016.06.027 Ünal, E. (2018). Volcanostratigraphy, Petrology and Magmatic Evolution of the Tendürek Volcano, Eastern Turkey. (PhD), Yuzuncu Yıl University, Institute of Natural and Applied Science, Van, Turkey. Wang, J., Xu, C., Freymueller, J. T., Li, Z., & Shen, W. (2014). Sensitivity of Coulomb stress change to the parameters of the Coulomb failure model: A case study using the 2008 Mw 7.9 Wenchuan earthquake. Journal of Geophysical Research: Solid Earth, 119(4), 3371-3392. https://doi.org/10.1002/2012JB009860 Wessel, P., Luis, J.F., Uieda, L., Scharroo, R., Wobbe, F., Smith, W.H.F., & Tian, D. (2019). The Generic Mapping Tools version 6. Geochemistry, Geophysics, Geosystems, 20, 5556-5564. https://doi:org/10.1029/2019GC008515 Yılmaz, Y., Güner, Y., & Şaroğlu, F. (1998) Geology of The Quaternary Volcanic Centres of The East Anatolia. Journal of Volcanology and Geothermal Research, 137 (85): 173-210. https://doi.org/10.1016/S0377-0273(98)00055-9 Yue, C., Qu, C. Y., Li, X. F., Meng, L. Y., Jiang, X. H., & Wu, D. L. (2025). Co-and postseismic stress transfer on different types of faults in Southern Tibet by the 2015 Mw7. 8 Gorkha earthquake. Journal of Structural Geology, 191, 105336. https://doi.org/10.1016/j.jsg.2024.105336 Zhou, P., Bastow, I. D., Kounoudis, R., Ogden, C. S., & Wang, Y. (2025). Lithospheric seismic structure of the Anatolian plate and its implications for plateau uplift: Evidence from joint inversion of receiver functions and surface waves. Geochemistry, Geophysics, Geosystems, 26, e2025GC012393. https://doi.org/10.1029/2025GC012393