مجله ژئوفیزیک ایران

مجله ژئوفیزیک ایران

بررسی نرخ لغزش بلندمدت و کوتاه‌مدت در گسله‌های شمال شرق ایران

نوع مقاله : مقاله پژوهشی‌

نویسندگان
1 دانشجوی دکتری ژئوفیزیک، دانشکده علوم زمین، دانشگاه تحصیلات تکمیلی علوم پایه زنجان، زنجان، ایران
2 استاد، دانشکده علوم زمین، دانشگاه تحصیلات تکمیلی علوم پایه زنجان، زنجان، ایران
3 دانشیار، دانشکده علوم زمین، دانشگاه تحصیلات تکمیلی علوم پایه زنجان، زنجان، ایران
چکیده
بررسی نرخ لغزش گسله‌های دارای گسیختگی سطحی و کم‌عمق، برای ارزیابی خطر زمین‌لرزه اهمیت دارد. از آنجائیکه نرخ تغییرشکل لیتوسفر در بازه زمانی کمتر از یک میلیون سال ثابت است، نرخ‌های لغزش حاصل از روش‌های کوتاه‌مدت و بلندمدت می‌تواند با هم مشابه باشند. با اینحال مشاهدات موجود، نشان می‌دهد که اختلافات زیادی در نرخ‌های تغییرشکل ارائه شده برای گسله‌های ایران وجود دارد. این اختلافات ممکن است در ارتباط با محدودیت‌های ذاتی دو روش بلندمدت و کوتاه‌مدت، کیفیت داده‌های این دو روش و یا تغییرات زمانی نرخ لغزش باشد. در این مطالعه، با تمرکز بر گسله‌های فعال شمال‌شرق ایران، همه نرخ‌های لغزش‌ بلندمدت (زمین‌شناسی) و کوتاه‌مدت (ژئودزی) موجود را جمع‌آوری و کیفیت نرخ‌های موجود را بررسی و نرخ‌های لغزش دارای بالاترین کیفیت در هر دو رویکرد را با یکدیگر مقایسه کردیم. نتایج این بررسی نشان می‌دهد که نرخ‌های لغزش با یکدیگر رابطه خطی دارند، ولی مقادیر نرخ لغزش کوتاه‌مدت در بیشتر موارد از نرخ لغزش بلند‌مدت بطور میانگین حدود 3/1 میلی‌متر برسال بیشتر است. این تفاوت ناشی از در نظر گرفته‌شدن تغییرشکل در خارج از گسل مورد بررسی است. روش‌های بلندمدت، نرخ لغزش را در امتداد یک گسله خاص بررسی می‌کند، در حالی که روش‌های کوتاه‌مدت اغلب نرخ یک گسله اصلی را به همراه نرخ تغییرگسله‌های مجاور آن اندازه‌گیری میکند. رابطه خطی بین نرخ‌های لغزش بلندمدت و کوتاه‌مدت، وتصادفی بودن تغییرات زمانی نرخ لغزش، وجود تغییرات زمانی نرخ لغزش را حداقل برای گسله‌های شمال‌شرق ایران رد می‌کند. برای گسله‌های بزرگ مقداری از تفاوت بین نرخ‌های بلندمدت و کوتاه‌مدت در ارتباط با این است که نرخ‌های گزارش شده مربوط به قسمت‌های مختلفی از سیستم گسلی هستند. رابطه خطی بین نرخ‌های لغزش بلندمدت و کوتاه‌مدت می‌تواند برای پیداکردن داده‌های پرت مورد استفاده قرار بگیرد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Investigation of long- and short-term slip rates of active faults in northeastern Iran

نویسندگان English

Marzieh Shabani 1
Abdolreza Ghods 2
Esmail Shabanian 3
1 Ph.D. Student, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
2 Professor, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
3 Associate Professor, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran
چکیده English

The analysis of fault slip rates plays a crucial role in assessing seismic hazards and understanding the kinematic behavior of active faults. This is particularly critical in regions like Iran, where instrumental earthquake catalogs often lack sufficient temporal coverage (less than 100 years) to reliably estimate seismicity parameters like seismic recurrence intervals, especially for large-magnitude events (Mw > 7). Both long-term (geologic) and short-term (geodetic) approaches rely on measurements of near-surface displacements, and given the relative temporal stability of lithospheric deformation rates over timescales shorter than one million years, their results could be almost equal. However, significant discrepancies persist between published the long- and short-terms slip rates for major faults in Iran. The discrepancies could be related to inherent limitation of the two approaches, quality of their measurements, and also temporal variation of slip-rate. This study focuses on active faults in northeastern Iran, a seismically active deformation zone hosting several destructive earthquakes, to methodologically evaluate these inconsistencies. We compiled all available long-term and short-term slip rate estimates for the region, rigorously assessing their quality based on their used methodology and observational constraints. The lack of precise dating and use of different dating methods can each introduce some degree of uncertainty into long-term slip rate calculations. The length of GPS profile normal to a given active fault, quality of the observed GPS vectors, and presence of faults off the main active fault are influential factors controlling errors in short-term slip rate determinations. After excluding low-quality measurements, we performed comparative analysis of the most reliable estimates from both approaches. Our results demonstrate a linear correlation between geodetic and geologic slip rates, though with a systematic offset in which short-term rates exceed the long-term estimates by an average of ~1.3 mm/yr. The systematically larger estimate of short-term slip rates arises from inherent limitations in geodetic methods that persist despite advances in remote sensing observation technologies. Geological methods measure slip accumulation along an active fault, whereas geodetic techniques typically resolve cumulative deformation rates across a given fault systems or block boundary. Geodetic measurements require GPS stations to be positioned at least twice the seismogenic layer thickness away from the fault to properly capture strain accumulation, leading to the inclusion of nearby faults off the main active fault and thus higher estimates of slip rates. The linear relationship between long-term and short-term slip rates, and the stochastic nature of temporal changes in slip rate, reject the existence of temporal changes in slip rate, at least for the faults of northeastern Iran. For large faults, a portion of the difference between long-term and short-term rates is related to the fact that the reported rates pertain to different parts of the fault system. The established linear relationship provides a valuable framework for identifying outlier slip rates.

کلیدواژه‌ها English

Dating, GPS, InSAR, northeast Iran, slip rate
Ambraseys, N. N., & Melville, C. P. (2005). A history of Persian earthquakes. Cambridge university press.
Balco, G. (2011). Contributions and unrealized potential contributions of cosmogenic-nuclide exposure dating to glacier chronology, 1990–2010. Quaternary Science Reviews, 30(1-2), 3-27.
Baker, J., Bradley, B., & Stafford, P. (2022). Seismic Hazard and Risk Analysis. Cambridge University Press
Bennett, R. A., Friedrich, A. M., & Furlong, K. P. (2004). Codependent histories of the San Andreas and San Jacinto fault zones from inversion of fault displacement rates. Geology, 32(11), 961-964.
Bird, P. (2009). Long‐term fault slip rates, distributed deformation rates, and forecast of seismicity in the western United States from joint fitting of community geologic, geodetic, and stress direction data sets. Journal of Geophysical Research: Solid Earth, 114(B11).
Chevalier, M. L., Ryerson, F. J., Tapponnier, P., Finkel, R. C., Van Der Woerd, J., Haibing, L., & Qing, L. (2005). Slip-rate measurements on the Karakorum fault may imply secular variations in fault motion. Science, 307(5708), 411-414.
Chuang, R. Y., & Johnson, K. M. (2011). Reconciling geologic and geodetic model fault slip-rate discrepancies in Southern California: Consideration of nonsteady mantle flow and lower crustal fault creep. Geology, 39(7), 627-630.
DeMets, C., Gordon, R. G., Argus, D. F., & Stein, S. (1994). Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motions. Geophysical research letters, 21(20), 2191-2194.
Djamour, Y., Vernant, P., Bayer, R., Nankali, H. R., Ritz, J. F., Hinderer, J., ... & Khorrami, F. (2010). GPS and gravity constraints on continental deformation in the Alborz mountain range, Iran. Geophysical Journal International, 183(3), 1287-1301.
Duller, G. A. (2008). Luminescence Dating: guidelines on using luminescence dating in archaeology.
Dunai, T. J. (2010). Cosmogenic nuclides: principles, concepts and applications in the earth surface sciences. Cambridge University Press.
Farbod, Y., Shabanian, E., Bellier, O., Abbassi, M. R., Braucher, R., Benedetti, L., ... & Hessami, K. (2016). Spatial variations in late Quaternary slip rates along the Doruneh Fault System (Central Iran). Tectonics, 35(2), 386-406.
Fattahi, M., & Walker, R. T. (2007). Luminescence dating of the last earthquake of the Sabzevar thrust fault, NE Iran. Quaternary Geochronology, 2(1-4), 284-289.
Fattahi, M., Walker, R. T., Khatib, M. M., Dolati, A., & Bahroudi, A. (2007). Slip-rate estimate and past earthquakes on the Doruneh fault, eastern Iran. Geophysical Journal International, 168(2), 691-709.
Gold, R. D., Cowgill, E., Arrowsmith, J. R., Chen, X., Sharp, W. D., Cooper, K. M., & Wang, X. F. (2011). Faulted terrace risers place new constraints on the late Quaternary slip rate for the central Altyn Tagh fault, northwest Tibet. Bulletin, 123(5-6), 958-978.
Gosse, J. C., & Phillips, F. M. (2001). Terrestrial in situ cosmogenic nuclides: theory and application. Quaternary Science Reviews, 20(14), 1475-1560.
Hager, B. H., & Richards, M. A. (1989). Long-wavelength variations in Earth’s geoid: physical models and dynamical implications. Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences, 328(1599), 309-327.
Hollingsworth, J., Jackson, J., Walker, R., Reza Gheitanchi, M., & Javad Bolourchi, M. (2006). Strike-slip faulting, rotation, and along-strike elongation in the Kopeh Dagh mountains, NE Iran. Geophysical Journal International, 166(3), 1161-1177.
Hollingsworth, J., Nazari, H., Ritz, J. F., Salamati, R., Talebian, M., Bahroudi, A., ... & Jackson, J. (2010). Active tectonics of the east Alborz mountains, NE Iran: Rupture of the left‐lateral Astaneh fault system during the great 856 AD Qumis earthquake. Journal of Geophysical Research: Solid Earth, 115(B12).
Holt, W. E., & Haines, A. J. (1993). Velocity fields in deforming Asia from the inversion of earthquake‐released strains. Tectonics, 12(1), 1-20.
Javidfakhr, B., Bellier, O., Shabanian, E., Siame, L., Léanni, L., Bourlès, D., & Ahmadian, S. (2011). Fault kinematics and active tectonics at the southeastern boundary of the eastern Alborz (Abr and Khij fault zones): Geodynamic implications for NNE Iran. Journal of Geodynamics, 52(3-4), 290-303.
Khorrami, F., Vernant, P., Masson, F., Nilfouroushan, F., Mousavi, Z., Nankali, H., ... & Alijanzade, M. (2019). An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities. Geophysical Journal International, 217(2), 832-843.
Masson, F., Anvari, M., Djamour, Y., Walpersdorf, A., Tavakoli, F., Daignieres, M., ... & Van Gorp, S. (2007). Large-scale velocity field and strain tensor in Iran inferred from GPS measurements: new insight for the present-day deformation pattern within NE Iran. Geophysical Journal International, 170(1), 436-440.
Mazzotti, S., Leonard, L. J., Cassidy, J. F., Rogers, G. C., & Halchuk, S. (2011). Seismic hazard in western Canada from GPS strain rates versus earthquake catalog. Journal of Geophysical Research: Solid Earth, 116(B12).
McCaffrey, R. (2005). Block kinematics of the Pacific–North America plate boundary in the southwestern United States from inversion of GPS, seismological, and geologic data. Journal of Geophysical Research: Solid Earth, 110(B7).
Molnar, P. (1979). Earthquake recurrence intervals and plate tectonics. Bulletin of the Seismological Society of America, 69(1), 115-133.
Montillet, J. P., & Bos, M. S. (Eds.). (2019). Geodetic time series analysis in earth sciences. Springer.
Mousavi, Z., Fattahi, M., Khatib, M., Talebian, M., Pathier, E., Walpersdorf, A., ... & Walker, R. T. (2021). Constant Slip Rate on the Doruneh Strike‐Slip Fault, Iran, Averaged Over Late Pleistocene, Holocene, and Decadal Timescales. Tectonics, 40(6), e2020TC006256.
Mousavi, Z., Talebian, M., Amiri, M., Walker, R. T., Marshall, N., & Walpersdorf, A. (2025). Constancy of geologic and geodetic fault slip rates across the Arabia‐Eurasia collision revealed through two decades of observation. Tectonics, 44(3), e2024TC008380.
Mousavi, Z., Walpersdorf, A., Walker, R. T., Tavakoli, F., Pathier, E., Nankali, H. R. E. A., ... & Djamour, Y. (2013). Global Positioning System constraints on the active tectonics of NE Iran and the South Caspian region. Earth and Planetary Science Letters, 377, 287-298.
Nelson, M. S., & Rittenour, T. (2014). Using grain-size distribution to build water retention curves for alluvial sediments―Application to dose-rate calculation. In 14th International Conference on Luminescence and Electron Spin Resonance Dating Book of Abstracts: Université du Québec à Montréal, Montreal (p. 146).
Okada, Y. (1986). Surface deformation due to shear and tensile faults in a half-space. In International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts (Vol. 23, No. 4, p. 128). Elsevier BV.
Oskin, M., Perg, L., Shelef, E., Strane, M., Gurney, E., Singer, B., & Zhang, X. (2008). Elevated shear zone loading rate during an earthquake cluster in eastern California. Geology, 36(6), 507-510.
Pietsch, T. J., Olley, J. M., & Nanson, G. C. (2008). Fluvial transport as a natural luminescence sensitiser of quartz. Quaternary Geochronology, 3(4), 365-376.
Robbins, J. W., Smith, D. E., & Ma, C. (1993). Horizontal crustal deformation and large scale plate motions inferred from space geodetic techniques. Contributions of Space Geodesy to Geodynamics: Crustal Dynamics, 23, 21-36.
Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, S., Cakmak, R., ... & Karam, G. (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: Solid Earth, 111(B5).
Rizza, M., Mahan, S., Ritz, J. F., Nazari, H., Hollingsworth, J., & Salamati, R. (2011). Using luminescence dating of coarse matrix material to estimate the slip rate of the Astaneh fault, Iran. Quaternary Geochronology, 6(3-4), 390-406.
Savage, J. C., & Burford, R. O. (1973). Geodetic determination of relative plate motion in central California. Journal of Geophysical Research, 78(5), 832-845.
Shabanian, E., Bellier, O., Siame, L., Abbassi, M. R., Bourlès, D., Braucher, R., & Farbod, Y. (2012). The Binalud Mountains: A key piece for the geodynamic puzzle of NE Iran. Tectonics, 31(6).
Shabanian, E., Siame, L., Bellier, O., Benedetti, L., & Abbassi, M. R. (2009). Quaternary slip rates along the northeastern boundary of the Arabia-Eurasia collision zone (Kopeh Dagh Mountains, Northeast Iran). Geophysical Journal International, 178(2), 1055-1077.
Shahvar, M. P., Zare, M., & Castellaro, S. (2013). A unified seismic catalog for the Iranian plateau (1900–2011). Seismological Research Letters, 84(2), 233-249.
Siame, L. L., Shabanian, E., & Bellier, O. (2009). Extrusion tectonics and subduction in the eastern South Caspian region since 10 Ma: Comment. Geology, 37(12), e197-e198.
Thatcher, W. (2009). How the continents deform: The evidence from tectonic geodesy. Annual Review of Earth and Planetary Sciences, 37(1), 237-262.
Walker, M. (2005). Quaternary dating methods. John Wiley & Sons.
Walker, R. T., Bezmenov, Y., Begenjev, G., Carolin, S., Dodds, N., Gruetzner, C., ... & Rhodes, E. J. (2021). Slip‐rate on the main Köpetdag (Kopeh Dagh) strike‐slip fault, Turkmenistan, and the active tectonics of the South Caspian. Tectonics, 40(8), e2021TC006846.
Walters, R. J., Elliott, J. R., Li, Z., & Parsons, B. (2013). Rapid strain accumulation on the Ashkabad fault (Turkmenistan) from atmosphere‐corrected InSAR. Journal of Geophysical Research: Solid Earth, 118(7), 3674-3690.
Wang, M., & Shen, Z. K. (2020). Present‐day crustal deformation of continental China derived from GPS and its tectonic implications. Journal of Geophysical Research: Solid Earth, 125(2), e2019JB018774.
Watson, A. R., Elliott, J. R., Lazecký, M., Maghsoudi, Y., McGrath, J. D., & Walters, R. J. (2024). An InSAR‐GNSS velocity field for Iran. Geophysical Research Letters, 51(10), e2024GL108440.
Wintle, A. G. (1993). Luminescence dating of aeolian sands: an overview. Geological Society, London, Special Publications, 72(1), 49-58.