پهنه‌بندی و تحلیل خطر زمین‌لرزه در استان فارس

نوع مقاله : Articles

نویسندگان

1 دانشگاه تحصیلات تکمیلی صنعتی و فناوری پیشرفته، کرمان

2 دانشگاه اردکان، یزد

چکیده

در این مطالعه پهنه‌بندی خطر زمین‌لرزه بر روی سنگ‌بستر برای بیشینه شتاب زمین به روش تعیّنی و احتمالاتی در استان فارس انجام گردید. فهرست‌نامه‌ی یکنواختی تا سال 2016 شامل زمین‌لرزه‌های تاریخی و دستگاهی با بزرگای بیشتر از 4 در مقیاس Mw تهیه شد. با توجه به روند گسل‌ها و زمین‌شناسی منطقه، 23 چشمه بالقوه زمین‌لرزه به‌صورت پهنه‌ای در این منطقه در نظر گرفته شده و پارامترهای لرزه‌خیزی محاسبه گردید. در روش احتمالاتی با استفاده از نرم‌افزار OpenQuake بیشینه شتاب و سرعت زمین برای دوره بازگشت‌های 50 سال و 475 سال و نمودارهای منحنی خطر PGA و PGV برای دوره 50 سال رسم شد. نتایج نشان می‌دهد که بیشترین سطح PGA برای دوره بازگشت‌های 50 و 475 سال به‌ترتیب g 23/0 و g 6/0 و به روش تعیّنی g 8/0 می‌باشد. در استان فارس، چهار منطقه پر خطر در  شمال غرب، غرب، جنوب و جنوب شرق قرار دارد. این مناطق نزدیک به گسل‌های کازرون، قیر و زاگرس مرتفع می‌باشند که سابقه زمین‌لرزه‌های بزرگ تاریخی و دستگاهی را دارا هستند. به‌طورکلی می‌توان گفت که مناطق با تراکم جمعیت بالا و شهرهای مهم استان به دلیل نزدیک بودن به گسل‌های منطقه در مناطق با خطر بالا قرار دارند.

کلیدواژه‌ها


عنوان مقاله [English]

Seismic Hazard and Zoning in Fars Province

نویسندگان [English]

  • Parisa Ashjanas 1
  • Afsaneh Nasrabadi 1
  • Mohamad Reza Sepahvand 1
  • Seyed Hasan Mousavi Bafrouei 2
1 Graduate University of Advanced Technology, Kerman, Iran
2 Ardakan University, Iran
چکیده [English]

In this study, Seismic Hazard zoning was probed by studying seismogenic zones and earthquake data in a 150 km radius around the Fars province boundaries in the Zagros seismotectonic zone. Zagros is one of the most seismically active parts of Alpine-Himalayan seismic belt. Fars province located at latitude of 27.2° – 31.42° and longitude of 50.42° – 55.36°, respectively. In this study, seismotectonic zone was determined based on the location of interest, faults strikes, seismic records, and geological structure.
In the first step of process, an earthquake catalogue of the instrumental and historical earthquakes was prepared by assimilating them to a uniform magnitude type (Mw) from 8th century until September 2016. Then, by using the Uhrhammer (1986) and Gardner and Knopoff (1974) methods in 1974, aftershocks and foreshocks were eliminated from the catalogue to have main earthquakes only. After the elimination of aftershocks and foreshocks, 2181 earthquakes remained as the main earthquakes in catalogue and their completeness magnitude was calculated by ZMap software. Afterwards, it was tried to recognize all the active faults around the sites; therefore, 23 area sources were introduced within the studied area from faults, historical and instrumental earthquakes. After introducing area sources, seismic parameters such as beta and lambda were calculated for each part using Kijko software. Similarly, space distribution function portion of each source was calculated. In addition, the results of six magnitude studies utilizing step method carried out by Mousvai et al. (2014) was used in this paper. In the deterministic approach, Pick Ground Acceleration (PGA) over bedrock was computed using two attenuation equations, Campbell and Bozorgnia (2008) and Boor and Atkinson (2008), using a MATLAB software for Fars province. Besides, in the probabilistic approach, PGA and pick ground velocity, PGV, were calculated using the same values in the attenuation equations that were used in the deterministic method using OpenQuake, one of the distinguished programs in seismic hazard analysis to determine the PGA on bedrock. The probabilistic approach was carried out on a grading area using a 10 km zonation map. PGA was calculated and covered 63% and 10% probability of exceedance in one life cycle of 50 and 475 years were presented, and hazard curves were calculated for 50 and 475 years using OpenQuake software. Probabilistic study resulted maximum PGA values in the periods of 50 and 475 years to be 0.23 g and 0.6 g respectively .These maximum PGA values centered on Kazeroon. After Kazeroon, Shiraz and Lamerd have the highest levels of hazard risk of cities in Fars province. Moreover, using the deterministic approach and the two attenuation equations, the obtained maximum PGA values fell between 0.68 g and 0.75 g. Finally, the results were compared with previous studies like Hamzeloo (2005), Ghafory-Ashtiany (1999) and Mousavi (2014).

کلیدواژه‌ها [English]

  • Hazard Analysis
  • Zagros
  • Fars province
  • Seismogenic Zone
  • Pick Ground Acceleration
  • Openquake Software
  1. Campbell, K.W. and Bozorgnia, Y. (2003) Updated near-source ground-motion (attenuation) relations for the horizontal and vertical components of peal ground acceleration and acceleration response spectra. Bulletin of the Seismological Society of America, 93, 314-331.
  2. Zare, M. (1384) An Introduction to Applied Seismology. International Institute of Earthquake Engineering and Seismology (in Persian).
  3. Frankel, A. (1995) Mapping seismic hazard in the Central and Eastern United States. Seismological Research Letters, 66, 8-21.
  4. Shi, Z., Yan, J., and Gao, M. (1992) Research on the principles and methodology of seismic zonation-results of the trial in north China. Acta Seismologica Sinica, 5, 305-314.
  5. Nowroozi, A. (2005) Attenuation relations for peak horizontal and vertical accelerations of earthquake ground motion in Iran: a preliminary analysis. Journal of Seismology and Earthquake Engineering, 7, 109-128.
  6. Zafarani, H., Mousavi, M., Noorzad, A.S. and Ansari, A. (2008) Calibration of the specific barrier model to Iranian plateau earthquakes and development of physically based attenuation relationships for Iran. Soil Dynamics and Earthquake Engineering, 28, 550-576.
  7. Ghasemi, H., Zare, M., Fukushima, Y. and Koketsu, K. (2009) An empirical spectral ground motion model for Iran. Journal of Seismology, 13, 499-515.
  8. Shoja Taheri, J., Naserieh, S. and Hadi, G. (2010) A test of the applicability of NGA models to the strong ground -motion data in the Iranian plateau. Journal of Earthquake Engineering, 14, 278-292.
  9. Boore, D.M. and Atkinson, G.M. (2008) Ground motion prediction equations for the average horizontal component of PGA, PGV, and 5%- damped PSA at spectral periods between 0.01 s and 10.0 s. Earthquake Spectra, 24, 99-138.
  10. Campbell, K.W. and Bozorgnia, Y. (2008) NGA ground motion model for the geometric mean horizontal 139 component of pga, pgv, pgd and 5% damped linear elastic response spectra for periods ranging from 0.01 To 10 S. Earthquake Engineering Research Institute, 24(1), 139-172.
  11. Chiou, B.S.J. and Youngs, R.R. (2008) An NGA model for the average horizontal component of peak ground motion and response spectra. Earthquake Spectra, 24, 173-215.
  12. Tavakoli, B. and Ghafory-Ashtiany, M. (1999) Seismic hazard assessment of Iran. Annali Di Geofysica, 42(6), 2013-2021.
  13. Mousavi, S.H. and Mirzaei, N., Shabani, E., and Eskandari-Ghadi, M. (2004) Seismic hazard zoning in Iran and estimating peak ground acceleration in provincial capitals. The Journal of the Earth and Space Physics, 4, 15-38 (in Persian).
  14. Hamzehloo, H., Alikhanzadeh, A., Rahmani, M., and Ansari, A. (2012) Seismic hazard maps of Iran. Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal.
  15. Vernant, P., Nilforoshan, F., Hatzfeld, D., Abbassi, M.R., Vigny, C., and Masson, D. (2004) Present-day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman. Geophysical Journal International, 157(1), 381-398.
  16. Berberian, M. (1995) Master ''blind'' thrust faults hidden under the zagros folds: active basement tectonics and surface morpho-tectonics. Tectonophysics, 241, 193-224.
  17. Berberian, M. (1994) Natural Hazards and the First Earthquake Catalogue of Iran. International Institute of Earthquake Engineering and Seismology, 1, 620.
  18. Mousavi, S.H. and Mirzaei, N., and Shabani, E. (2014) A declustered earthquake catalog for the Iranian plateau. Annals of Geophysics, 57(6), 1-25.
  19. Uhrhammer, R.A. (1986) Characteristics of northern and central California seismicity. Earthquake Notes, 57, 21.
  20. Gardner, K. and Knopoff, L. (1947) Is the sequence of earthquakes in southern California, with aftershocks removed, Poissonian? Bulletin of the Seismological Society of America, 64(5), 1363-1367.
  21. Zare, M. (1999) Contribution a' l' E'tude des Mouvements Forts en Iran; du Catalogue Aux Lois D'atte'nuation. Observatoire de Grenoble et Laboratoire de Geogphysique Interne et Tectoniphysique, L' Universite' Joseph Fourier - Grenoble I.
  22. Ambraseys, N.N. and Melville, C.P. (1982) A history of Persian earthquakes. Geological Magazine, 120, 410.
  23. Nowrozi, A. (1985) Empirical relations between magnitudes and fault parameters for earthquakes in Iran. Bulletin of the Seismological Society of America, 75(5), 1327-1338.
  24. Wells, D.L. and Coppersmith, K.J. (1994) New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. Bulletin of the Seismological Society of America, 84(4), 974-1002.
  25. Kijko, A. and Sellevoll, M.A. (1992) Estimation of Earthquake Hazard Parameters from Incomplete Data Files. Part II, Incorporation of Magnitude Heterogeneity. Bulletin of the Seismological Society of America, 82, 120-134.
  26. Ambraseys, N.N. (1989) Temporary seismic quiescence: SE Turkey. Geophysical Journal, 96, 311-331.
  27. Mirzaei, N., Gao, M., and Chen, Y.T. (1997) Evaluation of uncertainty of earthquake parameters for the purpose of seismic zoning of Iran. Earthquake Research in China, 11, 197-212.
  28. Mousavi, S.H. (2014) Deaggregation of Seismic Hazard in Iran and Evaluating the Importance of Site Effects for Some Selected Sites. Ph.D. Thesis (in Persian).
  29. Pagani, M., Monelli, D., Weatherill, G., Danciu, L., Crowley, H., Silva, V., Henshaw, P., Butler, L., Nastasi, M., Panzeri, L., Simionato, M., and Vigano, D. (2014) OpenQuake-engine: An open hazard (and risk) software for the Global Earthquake Model. In press in Seismological Research Letters.
  30. Field, E.H., Jordan, T.H. and Cornell, C.A. (2003) OpenSHA - a developing community modeling environment for seismic hazard analysis. Seismological Research Letters, 74, 406-419.
  31. Berberian, M. (1976) Contribution to the Seismotectonics of Iran, Part II. Geological Survey of Iran, Report, 39, 516.