Risk-Targeted Probabilistic Seismic Hazard Analysis for Siraf Port

Document Type : Research Article


in Earthquake Engineering, Shahid Beheshti University, Tehran, Iran


1. Introduction
One of the major problems facing most of the world's major metropolises and cities is natural hazards. In seismic countries, one of the most catastrophic is the earthquake event. Using statistical and probabilistic methods called seismic hazard analysis it is possible to ensure the safety of structures against earthquakes. Every year, a lot of researches have been done to determine the hazard of earthquakes around the world; Therefore, it is necessary to use new and up-to-date methods based on which seismic hazard maps can be updated in Iran. In this study, using a probabilistic approach and risk-targeted hazard analysis approach according to ASCE 07-10, the seismicity of Siraf port in Bushehr province was investigated.
2. Materials and Methods
In the present study, in order to investigate the seismic status of the site, a set of historical and instrumental seismic data with a time coverage up to 2019 up to a radius of 150 km was used and seismic sources were modeled. For this purpose, seismic sources in the desired area, using geological maps and satellite images, were determined and a suitable model of seismic sources in the region was presented.
 The list of earthquakes that occurred in the project area was made through documents, books, and Accelerometer. The defect in the catalog were eliminated by using the Kijko -Sellevoll method. In order to achieve the Poisson distribution of events, foreshocks and aftershocks were eliminated using Gardner and Knopo methods and Grünthal method. Finally, seismicity parameters were calculated based on data analysis in EZ-FRISK 7.43 (2010). The results of seismic hazard analysis using the probabilistic method for Siraf port are presented as a risk-based at the design level for a return period of 2475 years.
3. Study Area
Siraf port is located in Bushehr province near Kangan city in the south of Iran, between the south and southwest of the country (27.6667 °N, 52.3425 °E). It is one of the oldest ports in Iran, which is located between Kangan port and Assaluyeh port.
The geological structure of the site follows the general trend of the Zagros with a northwest-southeast trend. The location of the site from a geomorphological point of view has a flat and plain topography and from the point of view of structural zones of Iran, it is located in the folded Zagros (Darvishzadeh, 1991).
4. Results and Discussion
4.1. Determining the maximum horizontal acceleration of the ground motion
Using the results of the probabilistic method, the parameters of the maximum acceleration values of the horizontal component of the site at the seismic levels of operation basis level (OBL), design basis level (DBL) and maximum consider Earthquake (MCE) are 0.11g, 0.39g and 0.61g, respectively.
4.2. Risk-Targeted response spectrum for design level
The design response spectrum based on risk concept (ASCE 07-10) for this site has higher values in the entire period interval (approximately 12%) than the design spectrum with a probability of exceedance 10% and 2% in 50 years.
The increase in the values of the risk-based spectrum in the site compared to the uniform hazard spectrum is due to uncertainty in the collapse capacity of the designed structures. Therefore, the probability of collapse and failure of structures designed according to this spectrum by changing from one place to another and by changing the shape of the seismic hazard curve, leads to the probability of non-uniform collapse.
According to the Hazard Zoning Map of Iran in Regulation 2800, the location of the site confirms the level of high seismic hazard and the amount of acceleration of the design is 0.3gacceleration. While the earthquake hazard analysis of this region with a probability of exceedance 2% and 10% in 50 years has determined the parameters of maximum horizontal acceleration 0.61g and 0.39g, respectively.
The spectrum estimated in Standard 2800 is based on 10 percent probability of exceedance within a 50-year period with a Return period of 475 years. In seismically active areas where earthquakes occur most frequently, such as the west, southwest, and south coasts of the country, this method may be a logical one. But in areas where earthquakes are less common or the sensitivity of the area or site is important, the prediction of an earthquake with a return period of 475 years is under-predicted; Therefore, the definition of a maximum considered earthquake with a 2 percent probability of exceedance within a 50-year period with a Return period of 2475 years should be reconsidered.
Finally it is worth mentioning that the estimated probability of collapse in 50 years for a structure designed for the probability of exceedance 2% in 50-years, with the 2/3 factor, is indeed more geographically uniform than that designed for the probability of exceedance 10% in 50-years ground motions, without any factor.
5. Conclusion
Due to the high seismicity of Iran and especially the high importance of the southern regions of the country, it is recommended that the spectrum of regulations of the country (including standard 2800) be extensively studied and updated. Therefore, it is recommended to modify the spectrum in these regulations by updating the design spectrums of these regulations, using the methods available in valid standards such as ASCE7, in which earthquake estimation has been done properly. And for very important areas (including Tehran, Bushehr and Tabriz) due to the hazard of earthquake and irreparable damage, it is recommended to use the design spectrum based on the concept of risk-targeted according to ASCE 7-10.
The results of the study indicate that the seismic values of the spectrum obtained according to Regulation ASCE 07-10 are different from the proposed values for this area in the 2800 standard. The reason for this is the uncertainty in the seismic design of the structure that the risk-targeted approach is able to take into account and leads to achieving a uniform level of geographical distribution to prevent the collapse of the structure.


Reference: (In Persian)
Aghanbati, A. (2004). زمین‌شناسی ایران[Geology of Iran]. Tehran, Iran: Geological Survey and Mineral Exploration of Iran.
Ashja Nas, P., Nasrabadi, A., Sepahvand, M. R., & Mousavi Befroui, S. (2018).پهنه‌بندی و تحلیل خطر زمین‌لرزه در استان فارس [Zoning and earthquake hazard analysis in Fars province]. Journal of Earthquake Science and Engineering, 5(4), 21-36.
Committee for the Review of Earthquake Design Regulations (Fourth Edition). (2015). آئین نامه طراحی ساختمان‌ها در برابر زلزله (استاندارد 2800) [Earthquake design regulations (standard 2800)]. Tehran, Iran: Ministry of Roads and Urban Development, Road, Housing and Urban Development Research Center.
Darvishzadeh, A. (1991). زمین‌شناسی ایران [Geology of Iran]. Tehran, Amirkabir, Neda Publications, 901 pages.
Ghodrati Amiri, Gh., Razavian Amrei, S. A. R., & Mirhashemi, S. M. (2010).
طیف خطر یکسان برای مناطق مختلف جنوب شهر تهران [H‌o‌r‌i‌z‌o‌n‌t‌a‌l u‌n‌i‌f‌o‌r‌m h‌a‌z‌a‌r‌d s‌p‌e‌c‌t‌r‌a f‌o‌r d‌i‌f‌f‌e‌r‌e‌n‌t s‌o‌u‌t‌h‌e‌r‌n p‌a‌r‌t‌s o‌f T‌e‌h‌r‌a‌n]. Sharif Civil Engineering Journal, 26(3), 51-60.
Ghodrati Amiri, Gh., Razavian Amrei, S. A. R., & Tahmasebi Borujeni, M. (2015). تحلیل خطر لرزه ای و تهیه طیف خطر یکسان برای مناطق مختلف شهر کرمان [Seismic hazard analysis and uniform hazard spectra for different regions of Kerman]. Journal of Structural and Construction Engineering, 2(2), 43-51.
Iftikharnejad, J. (1980). تفکیک بخش‌های مختلف ایران از نظر وضع ساختمانی در ارتباط با حوضه‌های رسوبی [Separation of different parts of Iran in terms of structural status in relation to sedimentary basins]. Journal of the Petroleum Association, 82, 19 - 28.
Japan International Cooperation Agency (JICA). (2001). ریز پهنه‌بندی لرزه‌ای تهران بزرگ[Greater Tehran seismic zoning], in collaboration with the Greater Tehran Earthquake and Environmental Studies Center. Final report, available in the National Database of Earth Sciences.
Nojwan, K, Barzegari A, Mohammadian M. (2020). تحلیل خطر احتمالی زمین‌لرزه با در نظر گرفتن مفهوم ریسک محوری (مطالعه موردی الفین ۱۴) [Probabilistic earthquake hazard analysis with considering risk-based concept (Case study of olefin 14)]. Disaster Prevention and Management Knowledge, 10(1), 74-90.
Shayan, S., & Zare, Gh.R. (2014). پهنه‌بندیزمین‌لرزه‌هایرخ‌دادهدراستانفارسطیسال‌های1900تا2010میلادی ومقایسهآنبادیگریافته‌هایپژوهشی [Zoning of earthquakes that occurred in Fars province during 1900 to 2010 AD and comparing it with other research findings]. Geographical Research Quarterly, 29(1), 89-104.
Yousefi Sabouri, M., & Taghikhany, T. (2015). تجزیه‌وتحلیل خطر لرزه‌ای شهر تبریز با توجه به اثر پدیده‌ی حوزه‌ی نزدیک[Nea‌r-f‌i‌e‌l‌d e‌f‌f‌e‌c‌t i‌n p‌r‌o‌b‌a‌b‌i‌l‌i‌s‌t‌i‌c s‌e‌i‌s‌m‌i‌c h‌a‌z‌a‌r‌d a‌n‌a‌l‌y‌s‌i‌s a‌n‌d d‌i‌s‌a‌g‌g‌r‌e‌g‌a‌t‌i‌o‌n o‌f tTa‌b‌r‌i‌z c‌i‌t‌y]. Sharif Civil Engineering Journal, 31(2), 23-34.
Zare. M. (2009). مبانی تحلیل خطر زمین‌لرزه [Basics of earthquake risk analysis]. Tehran, International Institute of Earthquake Engineering and Seismology.
References: (In English)
Abrahamson, N., Silva, W. (2008). Summary of the Abrahamson and Silva NGA Ground motion relations. Earthquake Spectra, 24(1), 67–97.
Algermissen, S. T., Perkins, D. M., Thenhaus, P. C., Hanson, S. L., & Bender, B. L. (1982). Probabilistic estimates of maximum acceleration and velocity in rock in the contiguous United States. U. S. Geological Survey, Open-File Report 82-1033.
Ambraseys, N. N., & Jackson J. A. (1998). Faulting associated with historical and recent earthquakes in the Eastern Mediterranean region. Geophysical Journal International, 133(2), 390-406.
Ambraseys, N. N., & Melville, C. P. (1982). A history of Persian earthquakes. London, England: Cambridge.
Ambraseys, N. N., Simpson, K. U., & Bommer, J. J. (1996). Prediction of horizontal response spectra in Europe. Earthquake Engineering and Structural Dynamics, 25(4), 371-400.
ASCE Standard. (ASCE/SEI 7-10). (2010). Minimum design loads for buildings and other structures. Virginia: American Society of Civil Engineers, Alexander Bell Drive, Reston. Manufactured in the United States of America.
ASCE Standard. (ASCE/SEI 7-5). (2005). Minimum design loads for buildings and other structures. American Society of Civil Engineers, Reston, Virginia, Manufactured in the United States of America.
Bolt, B. A. (2003). Earthquakes, 5th ed. New York, NY: W. H. Freeman and Co.
Boore, D. M., Joyner, W. B., & Fumal, T. E. (1997). Equations for estimating horizontal response spectra and peak acceleration from western North American earthquakes: A summary of recent work. Seismological research letters, 68(1), 128-153.
Bozorgnia, Y., & Bertero, V. V. (2004). Earthquake engineering, from engineering seismology to performance-based engineering. Boca Ratón: CRC.
Campbell, K. W., & Bozorgnia, Y. (2003). Updated near-source ground-motion (attenuation) relations for the horizontal and vertical components of peak ground acceleration and acceleration response spectra. Bulletin of the Seismological Society of America, 93(1), 314-331.
Campbell, K., Bozorgnia, Y. (2008). NGA ground motion model for the geometric mean horizontal component of PGA, PGV, PGD and 5%-damped linear elastic response spectra for periods ranging from 0.01 to 10s. Earthquake Spectra, 24(1), 139–171.
Chiou, B. S., & Youngs, R. R. (2008). An NGA model for the average horizontal component of peak ground motion and response spectra. Earthquake Spectra, 24(1), 173–215.
Cornell, C. A. (1968). Engineering seismic risk analysis. Bulletin of the Seismological Society of America, 58(5), 1583–1606
Douglas, J., Ulrich, T., & Negulescu, C. (2013). Risk-targeted seismic design maps for mainland France. Natural Hazards, 65, 1999–2013.
Gardner, J. K., & Knopo. L. (1974). Is the sequence of earthquakes in Southern California, with aftershocks removed, Poissonian? Bulletin of the Seismological Society of America, 64(5), 1363-1367.
Ghodrati Amiri, G., Μotammed, R., Rabet Eshaghi, H. (2003). Seismic hazard assessment of metropolitan Tehran, Iran. Earthquake Engineering, 7(3), 347-372.
Grünthal, G. (Ed.). (1998). European Macroseismic Scale 1998. European Seismological Commission (ESC). Luxembourg: Ministere de la Culture, de L´Enseignement Superieur et de la Recherche.
Gupta, I. D. (2002). The state of the art in seismic hazard analysis. ISET Journal of Earthquake Technology, 39(4), 311-346.
Gutenberg, B., & Richter, C. F. (1944). Frequency of earthquakes in California. Bulletin of the Seismological Society of America, 34(4), 185-188.
Kijko, A. (2001). HN2 program (ver. 2.08): Seismic Hazard assessment from incomplete and uncertain data. Council for Geo science, Geological Survey of South Africa.
Kijko, A., & Sellevoll, M. (1992). Estimation of earthquake hazard parameters from incomplete data files. Part II. Incorporation of magnitude heterogeneity Bulletin of the Seismological Society of America, 82(1), 120-134.
Kijko, A., & Sellevoll, M. A. (1989). Estimation of earthquake hazard parameters from incomplete data files. Part I. utilization of extreme and complete catalogues with different threshold magnitudes. Bulletin of the seismological Society of America, 79(3), 645-654.
Kramer, S. L. (1996). Geotechnical earthquake engineering. New York, NY: Springer.
Lantada, N., Pujades, L., & Barbat, A. (2009). Vulnerability index and capacity spectrum based methods for urban seismic risk evaluation; A comparison. Net Hazards, 51(3), 501-524.
Liel, A. L. N., Raghunandan, M., & Champion, C. (2015). Modifications to risk-targeted seismic design maps for subduction and near-fault hazards. Paper presented at 12th International Conference on Applications of Statistics and Probability in Civil Engineering (ICASP12). Vancouver, Canada.
Luco, N., Ellingwood, B. R., Hamburger, R. O., Hooper, J. D., Kimball, J. K., & Kircher, C. A. (2007). Risk-targeted versus current seismic design maps for the conterminous United States. Proceedings of the Structural Engineers Association of California 76th Annual Convention.
McGuire, R. K. (2004). Seismic hazard and risk analysis.Oakland, CA: Earthquake Engineering Research Institute.
Mirzaei, N., Gao, M., & Chen, Y. T. (1998). Seismic source regionalization for seismic zoning of Iran: Major seismotectonic provinces. Earthquake Prediction Research, 7(4), 465–495
National Earthquake Hazards Reduction Program. (2009). NEHRP recommended provisions, for seismic regulations for new buildings and other structures (FEMA P-750). Prepared by the building seismic safety council of the National Institute of Building Sciences for the federal emergency management agency of the U.S. Department of Homeland Security, Washington, D.C. catalog No. 09349-2.
Nowroozi, A. A. (1985). Empirical relations between magnitudes and fault parameters for earthquakes in Iran. Bulletin of the Seismological Society of America, 75(5), 1327-1338.
Petersen, M. D., Harmsen, S. C., Jaiswal, K. S., Rukstales, K. S., Luco, N., Haller, K. M., Mueller, C. S., & Shumway, A. M. (2018). Seismic hazard, risk, and design for South America. Bulletin of the Seismological Society of America, 108(2), 781–800.
Ramezani Besheli, P., Zare, M., Ramazani Umali, R., & Nakhaeezadeh, G. (2015). Zoning Iran based on earthquake precursor importance and introducing a main zone using a data-mining process. Natural Hazards, 78(2), 821–835.
Scordilis, E. M. (2006). Empirical global relations converting MS and mb to moment magnitude. Journal of Seismology, 10(2), 225–236.
Sengara, I. (2012). Investigation on risk-targeted seismic design criteria for a high-rise building in Jakarta-Indonesia. Paper presented at 5th World Conference of Earthquake Engineering (WCEE). Lisboa, Portugal.
Sengara, W., Irsyam, M., Sidi, I, D., Mulia, A., Asrurifak, M., Hutabarat, D., & Partono, W. (2020). New 2019 Risk-Targeted Ground Motions for Spectral Design Criteria in Indonesian Seismic Building Code. E3S Web of Conferences 156, 03010, 4th International Conference on Earthquake Engineering & Disaster Mitigation.
Shoja Taheri, J., Naserieh, S., & Ghofrani, H. (2007). ML and MW Scales in the Iranian Plateau based on the strong-motion records. Bulletin of the Seismological Society of America, 97(2), 661–669.
Shroder, J. F., & Wyss, M. (2014). Earthquake hazard, risk and disasters. USA: Academic Press.
Silva, V., Crowley, H., & Bazzurro, P. (2016). Exploring risk-targeted hazard maps for Europe. Earthquake Spectra, 32(2), 1165-1186.
Slemmons, D. B. (1977). Faults and earthquake magnitude. U. S. Army Engineer Waterways Experiment Station, Vicksburg, Miss., Miscellaneous Paper S-73-1, Report 6..
Soleimanmeigooni, F., & Tehranizadeh, M. (2020). Uniform risk vs. uniform hazard spectral acceleration for different soil types in Alborze seismic zone. Asian Journal of Civil Engineering, 21, 67–79.
Uniform Building Code (UBC-97). (1997). Structural engineering design provisions. International Conference of Building Officials. Whittier, California.
Wells, L. D., & 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.
Zare, M. (2010). Principles of earthquake hazard Analysis. Tehran, Iran: International Institute of Earthquake Engineering and Seismology.
Zare, M., Amini, H., Yazdi, P., Sesetyan, K., Demircioglu, M. B., Kalafat, D., Tseriteli, N. (2014).  Recent developments of the Middle East catalog. Journal of Seismology,18(4), 749–772.