Earthquake risk zoning in southwestern Lorestan region and the environmental effects of earthquakes
Subject Areas :
1 - Geology, science and research branch Azad University, Tehran,Iran
Keywords: environmental effect, earthquake, southwestern Lorestan region, Zagros.,
Abstract :
Introduction The southwestern region of Lorestan, Zagros in Iran is known for its seismic activity, which is a result of the Arabian and Eurasian plates converging. This region is a part of the Alpine–Himalayan orogenic system, which was formed due to the closure of the Neo-Tethys oceanic during the Cenozoic era. Purpose This study aims to explore the environmental impact of earthquakes in this region, with a special focus on the effects on geological features such as hidden faults, numerous fractures, a sedimentary layer, the Gachsaran Formation, and Hormuz salt. Methodology The study involved the analysis of seismic waveforms collected from 2006 to 2019 from a network of 36 seismic stations. The quality factor of seismic body waves was estimated using the extended coda normalization method. Additionally, a quantitative morphometric evaluation was conducted through the Tu index to predict the catchment-scale suspended sediment yield on the scar area and derive the erosion rate affecting the landslide after the cut of the landslide dam by the Seymareh River. Results The study found that the attenuation of seismic waves in the Zagros area is significant due to geological features such as hidden faults, numerous fractures, a sedimentary layer, the Gachsaran Formation, and Hormuz salt. The spatial variation in Q values reveals that the attenuation is higher in the northern parts of the region than in the southern parts. The Seymareh Landslide, one of the largest rock mass movements on the Earth’s surface with an estimated volume of 44 Gm 3, is a significant geological event in this region. Conclusion The study concludes that earthquakes in the southwestern region of Lorestan, Zagros have a significant environmental impact, particularly on geological features. The significant attenuation of seismic waves in the area is due to the complex geological features, leading to gravity-induced phenomena with considerable implications for natural hazards. The Seymareh Landslide serves as a prime example of the large-scale geological changes that can occur as a result of seismic activity.
References:
-Yegane, A. G., Solgi, A., Uromeie, A., Maleki, Z., & Nezafati, N. (2018). Calculation of seismicity parameters and strong ground movement in Lorestan province (Boroujerd city) based on seismic data. Arabian Journal of Geosciences, 11(1), 1-14.
-Mahdavian Abbas, A. (2014). Rudbar Lorestan Dam Design and local Faults. Retrieved from http://www.civilica.com/Paper-120233.html
- Advances in seismic hazard and risk assessments (2019). Frontiers, 2(3).
- Department of Engineering Seismology, International Institute of Earthquake Engineering and Seismology (2014). Inception of activity and slip rate on the Main Recent Fault of Zagros Mountains, Iran. Retrieved from http://www.iiees.ac.ir/en/research/research-projects/2014/05/02/11541/
- Forouzan, A., Baradaran Eftekhari, M., Falahat, K., Dejman, M., Heidari, N., & Habibi, E. (2013). Psychosocial Needs Assessment among Earthquake Survivors in Lorestan Province with an Emphasis on the Vulnerable Groups. Social Determinants of Health Research Center, Welfare and Rehabilitation University of Medical Sciences, Tehran, Iran.
- Assist. Prof. Dr. Dlshad A. Marf Zamua (2014). Psychosocial Needs Assessment among Earthquake Survivors in Lorestan Province with an Emphasis on the Vulnerable Groups. Global Journal of Health Science, 6(5), 15-25.
- Shiranvand, H., & Hosseini, S. A. (2018). An analysis of dieback areas of Zagros oak forests using remote sensing data case study: Lorestan oak forest, Iran. Modeling Earth Systems and Environment, 4(1), 87-97.
- Abrari Vajari, K., Veiskarami, G., & Attar, F. (2015). Recognition of Endemic Plants in Zagros Region (Case Study: Lorestan Province, Iran). ECOLOGIA BALKANICA, 25(1), 121-131.
- Assist. Prof. Dr. Dlshad A. Marf Zamua (2016). Earthquakes, Archaeology and the ancient records in Mesopotamia and the Zagros. 3rd International Scientific Conference Archaeology and Heritage of Kurdistan.
- Nissen, E., Tatar, M., Jackson, J. A., & Allen, M. B. (2012). New views on earthquake faulting in the Zagros fold-and-thrust belt of Iran. Geophysical Journal International, 190(3), 1379-1402.
- Khademi, M., Amini, A., and Amini, A. (2016). Seismic wave attenuation in the Zagros region, southwest Iran, estimated using the empirical Green’s function method. Journal of Geophysics and Engineering, 13(5), 1007–1020.
- Khademi, M., Amini, A., and Amini, A. (2017). Sediment yield and erosion rate estimation in the Seymareh landslide area using the Tu index, southwest Iran. International Journal of Sediment Research, 32(2), 107–117.
- Masson, F., Chery, J., Hatzfeld, D., Martiond, J., Vernant, P., Tavakoli, F. & Ghafory-Ashtiani, M. (2005). Seismic versus aseismic deformation in Iran inferred from earthquakes and geodetic data. Geophys. J. Int 160: 217-226. McClay, K. R. (1992). Glossary of thrust tectonics terms. In: McClaly, K. R. (Ed.), Thrust Tectonics, London, Chapman & Hall, 419-433.
- McClay, K. R. (2000). Advanced structural geology for petroleum exploration, training course pamphlet, 503 (Unpublished booklet). McConnell, D. A. (1994). Fixed-hinge, basement-involved fault-propagation folds, Wyoming. Geological Society of America Bulletin 106: 1583-1593.
- McQuillan, H. (1968). Surface Asmari anticline fracture patterns at airphotograph scale, Acomparision with small scale fracture systems. Iranian Oil Operating Companies, Report No. 1134 (Unpublished).
- McQurrie, N. (2004). Crustal scale geometry of the Zagros fold-thrust belt, Iran. Journal of Structural Geology 26: 519-535.
